How does your internal body clock work. What factors influence your circadian rhythm. Can you effectively reset your sleep-wake cycle. How long does it take to adjust your biological clock. What are the best practices for aligning your circadian rhythm with your desired schedule.

Understanding the Circadian Rhythm: Your Body’s Internal Clock

The circadian rhythm is a complex biological process that regulates numerous physiological functions within our bodies. This internal clock operates on a roughly 24-hour cycle, dictating when we feel sleepy, alert, hungry, and even influencing our hormone production, body temperature, and blood pressure fluctuations.

At the center of this intricate system is the suprachiasmatic nucleus (SCN), located in the hypothalamus of the brain. This central clock synchronizes with the external light-dark cycle and communicates timing information to peripheral clocks found throughout the body in various organs and tissues.

Is the circadian rhythm the same for everyone? While the general pattern is similar, the specific timing can vary based on individual chronotypes. Some people are naturally early birds, others are night owls, and many fall somewhere in between. Age also plays a role, with teenagers typically having later rhythms and older adults tending towards earlier ones.

Key Components of the Circadian Rhythm

• Central clock (SCN) in the brain
• Peripheral clocks in organs and tissues
• Light-dark cycle synchronization
• Regulation of sleep-wake patterns
• Influence on hormone production
• Control of body temperature fluctuations

The Science Behind Circadian Rhythm Reset

Resetting your circadian rhythm is indeed possible, and it involves adjusting the timing of when your body naturally wants to sleep and wake. This process is influenced by external cues known as zeitgebers, which literally means “time-givers” in German.

Zeitgebers play a crucial role in either reinforcing your current circadian rhythm or shifting it earlier or later in the 24-hour cycle. Among these cues, light exposure stands out as the most powerful influencer of our internal clocks.

Primary Zeitgebers Affecting Circadian Rhythm

1. Light exposure (most influential)
2. Eating patterns
3. Exercise timing
4. Social interactions
5. Temperature changes

How significant can these changes be? A fascinating study demonstrated the impact of natural light exposure on circadian rhythms. Participants who went camping for a week, exposed only to natural light, showed remarkable adjustments in their sleep-wake cycles. Notably, night owls experienced the most dramatic shifts, with their rhythms aligning more closely with those of early birds.

Practical Strategies for Resetting Your Circadian Rhythm

Resetting your circadian rhythm requires a multi-faceted approach, focusing on various aspects of your daily routine. By implementing these strategies consistently, you can gradually shift your internal clock to better align with your desired schedule.

Light Exposure Management

How can you leverage light to reset your circadian rhythm? Start by exposing yourself to bright light early in the morning, ideally natural sunlight, for at least 10-15 minutes. This helps signal to your body that it’s time to be awake and alert. Throughout the day, try to get regular exposure to daylight.

In the evening, reduce your exposure to artificial light, especially blue light from electronic devices. Consider using blue light blocking glasses or apps that filter blue light on your devices. Create a dim, relaxing environment in your home as bedtime approaches.

Sleep Schedule Consistency

Maintaining a consistent sleep schedule is crucial for resetting your circadian rhythm. Try to go to bed and wake up at the same times every day, even on weekends. This consistency reinforces your body’s natural rhythms.

If you need to shift your sleep schedule, do so gradually. Adjust your bedtime and wake time by 15-30 minutes every few days until you reach your desired schedule.

Meal Timing Optimization

Can meal timing affect your circadian rhythm? Absolutely. Your digestive system and metabolism are closely linked to your internal clock. Try to eat your meals at consistent times each day, and avoid large meals close to bedtime.

Consider implementing a form of time-restricted eating, where you consume all your meals within a 10-12 hour window. This can help reinforce your body’s natural rhythms and improve overall metabolic health.

Exercise and Physical Activity Timing

Regular physical activity can have a profound impact on your circadian rhythm, but timing is key. Exercise can help reinforce your wake cycle when done earlier in the day, particularly in the morning or early afternoon.

How does evening exercise affect sleep? While some people may find that evening exercise doesn’t disrupt their sleep, others might experience difficulty falling asleep if they exercise too close to bedtime. If you prefer evening workouts, try to finish at least 2-3 hours before your intended sleep time.

Tailoring Exercise to Your Chronotype

• Early birds: Morning or early afternoon workouts
• Night owls: Late afternoon or early evening exercise
• In-between types: Midday workouts

Remember to listen to your body and adjust your exercise timing based on how it affects your sleep quality and overall energy levels.

Managing Jet Lag and Shift Work

Jet lag and shift work present unique challenges to maintaining a healthy circadian rhythm. These situations often require more deliberate strategies to reset your internal clock effectively.

Jet Lag Strategies

How can you minimize the effects of jet lag? When traveling across time zones, start adjusting your sleep schedule a few days before your trip. Upon arrival, expose yourself to sunlight at the appropriate times for your new time zone. This helps your body clock adapt more quickly.

For westward travel, try to stay awake until the local bedtime. For eastward travel, which is typically more challenging, consider short naps (20-30 minutes) to manage fatigue without disrupting nighttime sleep.

Shift Work Adaptation

Shift workers face ongoing challenges in maintaining a stable circadian rhythm. If possible, try to maintain a consistent shift schedule rather than rotating shifts frequently. Create a sleep-conducive environment at home, using blackout curtains and white noise machines if necessary.

Consider using light therapy lamps during night shifts to help stay alert, and wear dark sunglasses when leaving work in the morning to minimize light exposure when you need to sleep.

The Role of Melatonin in Circadian Rhythm Regulation

Melatonin, often referred to as the “sleep hormone,” plays a crucial role in regulating our circadian rhythms. This hormone is naturally produced by the pineal gland in response to darkness, signaling to our bodies that it’s time to prepare for sleep.

How does melatonin supplementation affect circadian rhythms? While melatonin supplements can be useful in certain situations, such as jet lag or shift work, they should be used judiciously and under the guidance of a healthcare professional.

Natural Melatonin Production Enhancement

• Limit exposure to blue light in the evening
• Create a dark sleep environment
• Maintain a consistent sleep schedule
• Avoid caffeine and alcohol close to bedtime
• Practice relaxation techniques before sleep

Remember, while melatonin supplements can be helpful in the short term, the goal should be to optimize your natural melatonin production through lifestyle changes.

Technology and Tools for Circadian Rhythm Management

In our modern, tech-driven world, various tools and applications can assist in managing and resetting your circadian rhythm. These range from simple light therapy devices to sophisticated sleep tracking apps.

Light Therapy Devices

Light therapy lamps or boxes can be particularly useful for individuals dealing with seasonal affective disorder (SAD) or those needing to shift their circadian rhythms. These devices mimic natural sunlight and can help regulate your body’s production of melatonin and serotonin.

Sleep Tracking Apps

Apps like RISE can predict your circadian rhythm and provide personalized recommendations for optimizing your sleep-wake cycle. These tools often use a combination of user input and device sensors to track sleep patterns and suggest improvements.

Smart Home Integration

How can smart home technology support circadian rhythm management? Smart lighting systems can be programmed to mimic natural light patterns, gradually brightening in the morning and dimming in the evening. Smart thermostats can adjust room temperature to promote better sleep, as our body temperature naturally drops at night.

While these technological aids can be helpful, it’s important to remember that they should complement, not replace, the fundamental lifestyle changes necessary for healthy circadian rhythm management.

Long-Term Health Implications of Circadian Rhythm Disruption

Maintaining a well-regulated circadian rhythm is not just about feeling more alert during the day and sleeping better at night. Chronic disruption of our internal clocks can have far-reaching health implications.

What are the potential consequences of long-term circadian rhythm disruption? Research has linked circadian rhythm disturbances to various health issues, including:

• Increased risk of cardiovascular disease
• Higher likelihood of developing metabolic disorders like diabetes
• Weakened immune function
• Elevated risk of certain cancers
• Cognitive decline and increased risk of neurodegenerative diseases
• Mood disorders such as depression and anxiety

Understanding these potential risks underscores the importance of prioritizing healthy circadian rhythm habits as part of overall wellness and disease prevention strategies.

The Circadian Rhythm-Gut Health Connection

Emerging research has revealed a fascinating link between our circadian rhythms and gut health. The gut microbiome, the complex ecosystem of microorganisms living in our digestive tract, appears to have its own circadian rhythms that interact with our body’s central clock.

How does this interaction affect our health? Disruptions to our circadian rhythms can alter the composition and function of our gut microbiome, potentially leading to digestive issues, altered metabolism, and even influencing our mood and cognitive function through the gut-brain axis.

To support both circadian and gut health, consider these strategies:

• Maintain consistent meal times
• Avoid late-night snacking
• Include a variety of fiber-rich foods in your diet
• Stay hydrated throughout the day
• Consider probiotic and prebiotic foods or supplements

By nurturing both your circadian rhythm and gut health, you can create a positive feedback loop that supports overall well-being and resilience against various health challenges.

How and When to Reset Your Circadian Rhythm

Feeling sluggish all day, yet wired at night? You may need to reset your circadian rhythm. This is your body’s internal clock that controls when you feel sleepy and when you feel alert. 

While your circadian rhythm is always ticking away inside your body, you can get out of sync with it with an irregular sleep schedule or night shift work, for example. Luckily, you can also reset it and get your sleep schedule, energy levels, and overall health back on track. 

Below, we’ll dive into what the circadian rhythm is, when you might need to reset it, and how to reset it naturally. Plus, we’ll share how the RISE app can make resetting your circadian rhythm easy. 

Advice from a sleep scientist:

“To reset your circadian rhythm, focus on light and when you get exposed to it. Get out in sunlight as soon as you can in the morning for at least 10 minutes, prioritize getting out in daylight throughout the day, and then make your evenings and nights dark. ”

Rise Science Advisor and Co-Director of the Center for Sleep and Circadian Sciences at Stanford University Dr. Jamie Zeitzer

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What is circadian rhythm?

Can you reset your circadian rhythm?

How to reset your circadian rhythm?

When to reset your circadian rhythm?

How long does it take to reset your circadian rhythm?

What are circadian rhythm sleep disorders?

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What is Circadian Rhythm?

The RISE app can predict your circadian rhythm each day.

Your circadian rhythm is your internal biological clock. It runs on a roughly 24-hour cycle and dictates when your body wants to sleep and wake up, when your energy levels rise and fall throughout the day, when you make certain hormones, and when your body temperature and blood pressure naturally fluctuate.  

But there’s more than just one body clock at work. 

There’s a central clock — known as the suprachiasmatic nucleus (SCN) — found in the hypothalamus of the brain. And then there are clocks in almost every tissue and organ system in your body. These are called peripheral clocks, and they can be found in places like your gut, immune system, and liver.  

The SCN is synchronized to the light-dark cycle of the outside world and it communicates this time with the peripheral clocks keeping them aligned to each other and the outside world. Together, all of these clocks tell your body when the best times are to eat, sleep, be alert, and so on. 

Your circadian rhythm follows a roughly 24-hour cycle. Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6123576/

Everyone’s circadian rhythm will look roughly the same, but the timing will be different depending on your chronotype. Your chronotype is whether you’re an early bird, night owl, or something in between. Morning people have earlier circadian rhythms, whereas night owls’ rhythms run later. 

Not sure what you are? We’ve covered how to find out your chronotype here.

Your circadian rhythm also changes with age. Teenagers’ circadian rhythms tend to skew later, while older adults’ rhythms tend to skew earlier. So, we naturally become more of an earlier riser as we age — and your teen’s tendency to lay in isn’t laziness.  

RISE can predict your circadian rhythm each day and show you a simple visualization of it in the app. You can then see when your body naturally wants to wake up and go to sleep, and when your peaks and dips in energy will most likely be throughout the day.

Finding out the timings of daily energy peaks and dips is the most popular feature among RISE users.

RISE users on iOS 1.202 and above can click here to see their circadian rhythm on the Energy screen.

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Can You Reset Your Circadian Rhythm?

Yes, you can reset your circadian rhythm. Resetting your circadian rhythm simply means resetting when your body naturally wants to go to sleep up and wake up. 

The timing of your circadian rhythm can be changed by zeitgebers, which is German for time-givers. Zeitgebers tell your circadian rhythm what time it is outside your body. 

They can either reinforce the timing of your circadian rhythm (i.e. confirm it’s running on time) or shift the timing earlier or later in the 24-hour cycle. 

Zeitgebers include: 

• Light (the most powerful one) 
• Eating 
• Exercising 

One illuminating study took participants camping for a week and exposed them to natural light only. Without laptop or smartphone screens or artificial light, their circadian clocks adjusted to match the light-dark cycle of the outside world. 

What’s even more impressive is that night owls showed the biggest changes. Their circadian rhythms shifted to look more like those of early birds. So, while night owls do exist, some extreme night owls may be that way because of bad habits like late-night light exposure.  

We turned to sleep researcher Dr. Jamie Zeitzer again for backup. 

“Your circadian rhythm isn’t set in stone. You can change the timing of it with cues like light exposure. For example, early morning light brings your circadian rhythm forward, whereas late-night light exposure pushes it back.” 

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How to Reset Your Circadian Rhythm?

The RISE app can guide you through 20+ sleep hygiene habits daily.

Now you know what your circadian rhythm is and that it’s possible to reset it, here’s how to get it back on track: 

• Shift your bedtime and wake times gradually: Move your sleep-wake times by 15 to 30 minutes every few days. This will give your circadian rhythm a chance to adjust to the gradual changes. Once you’ve reached your ideal schedule, be consistent with your sleep routine. 
• Shift your meal times: Shift meal times in the same direction as your sleep patterns and by the same amount. Avoid eating two to three hours before bed as this can disrupt your sleep, making it harder to stick to your new schedule. Consistency with meal times can also help keep your circadian rhythm in check once you’ve reset it. 
• Get bright light first thing: This resets your circadian rhythm for the day. Aim for at least 10 minutes of sunlight, or 15 to 20 minutes if it’s overcast or you’re getting light through a window. Once you’ve shifted your schedule, be consistent with when you get this early light. 
• Consider bright light therapy: This can help those with a circadian rhythm sleep disorder. A sleep specialist can prescribe bright light therapy to shift your circadian rhythm. As a DIY option, you can try a 10,000 lux light therapy lamp, which is useful if it’s dark out when you wake up. Sit about 16 to 24 inches from a lamp for 30 minutes in the morning. Slowly shift the time you get this light earlier as you shift your wake times. 
• Get daylight during the day: The more light you get during the day, especially daylight, the less sensitive you’ll be to light at night, and so the less evening light can disrupt your circadian rhythm.  
• Avoid light in the evenings: Light suppresses your sleep hormone melatonin and, when you get it in the evening, it pushes back your circadian rhythm. About 90 minutes before bed, dim the lights and put on blue-light blocking glasses. 
• Create a morning routine you look forward to: Getting up earlier can be hard. Plan morning activities you enjoy and activities that can wake you up faster. This could include having a cup of coffee, going for a run or walk, or doing yoga. Even if you’re usually a night owl, try scheduling your most challenging tasks for the day in the morning. This will help the earlier schedule stick. 
• Exercise during the day: A 2019 study found early morning or during the day exercise can help shift your circadian rhythm earlier. Just be sure to avoid intense workouts within an hour of bedtime as this can keep you up.
• Avoid caffeine and alcohol too late in the day: Both caffeine and alcohol can disrupt your sleep, which can mess with your circadian rhythm. Avoid caffeine about 12 hours before bed and alcohol three to four hours before bed. RISE can tell you exactly when to avoid each one daily. 
• Take a melatonin supplement: We don’t encourage taking melatonin every night, but it can be useful when you’re trying to make a big change to your sleep schedule. Taken at the right time, melatonin can help you feel sleepy when you usually wouldn’t and either bring forward or push back your circadian rhythm. We’ve covered more on when to take melatonin here.
• Use the RISE app: Pick a goal wake time with RISE’s smart schedule feature. The app will then give you a smart bedtime goal each night that gently shifts and trains your body to get the sleep you need on an earlier schedule. 

Beyond these key steps, it’s important to maintain good sleep hygiene. Sleep hygiene is the set of habits you can do to get a good night’s sleep. With good sleep hygiene, you’ll have an easier time falling asleep at your desired bedtime, keeping your circadian rhythm on track.  

Many of the habits above are a part of good sleep hygiene, such as getting light in the morning, and avoiding light, caffeine, intense exercise, and alcohol too close to bedtime. 

RISE can walk you through 20+ sleep hygiene habits each day and tell you the best time to do each one to make them more effective. 

Heads-up: It’s tempting to pull an all-nighter to fix your sleep schedule. But this won’t help. It’ll only give you more sleep deprivation, make you feel more sleepy, and further disrupt your circadian rhythm. Skip the all-nighter and focus on shifting your sleep-wake cycle in 15-to-30-increments instead. 

RISE users on iOS 1.202 and above can click here to set up their 20+ in-app habit notifications.

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When to Reset Your Circadian Rhythm?

The RISE app can work out how much sleep debt you have.

You might want to reset your circadian rhythm if: 

• You feel sleepiness throughout the day
• You struggle to sleep at night
• Your sleep-wake times don’t match your lifestyle 

Sleep problems and low energy are the most obvious reasons to reset your circadian rhythm. But being in circadian alignment (when your sleep-wake times and mealtimes match when your body wants to sleep and eat) isn’t just good news for your sleep and energy. 

Being in sync lowers your risk of type 2 diabetes, obesity, cardiovascular disease, and cancer. And research from 2023 found a disrupted circadian rhythm from mis-timed light exposure and food consumption can mess up your hormones and metabolism. 

Being in sync with your circadian rhythm can also make keeping your sleep debt low easier. Sleep debt is how much sleep you’ve missed out on recently. It’s compared against your sleep need, the genetically determined amount of sleep you need. 

Low sleep debt equals better energy, productivity, mood, and health (we recommend keeping your sleep debt below 5 hours to feel and function your best).  

Heads-up: We all have different sleep needs. When we looked at the sleep needs of 1.95 million RISE users aged 24 and up, we found they ranged from five hours to 11 hours 30 minutes. The median sleep need was eight hours, but 48% of users need eight hours of sleep or more.

You might be out of sync with your circadian rhythm if: 

• You work night shifts or rotating shifts 
• You’ve got social jet lag — or an irregular sleep schedule 
• You’re living at odds with your chronotype — like when a night owl needs to wake up early for work 
• You’re adjusting to a new time zone 

For more tips on how to reset your circadian rhythm, we’ve covered advice for specific situations, including: 

• How to get over jet lag 
• How to become a morning person (or shift your circadian rhythm earlier) 
• How to adjust to daylight saving time 
• How to reset your sleep schedule (including tips for shift workers) 

RISE can work out your individual sleep need and whether you’ve got any sleep debt. 

RISE users on iOS 1.202 and above can click here to view their sleep need and here to view their sleep debt.

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How Long Does it Take to Reset Your Circadian Rhythm?

Your circadian rhythm resets every 24 hours. But if you’re trying to shift the timing of it, it may take longer. 

How long it takes to shift the timing of your circadian rhythm will all depend on how much you’re trying to shift it by. We recommend moving your sleep-wake times by no more than 15 to 30 minutes every few days until you reach your ideal schedule. 

It may take a few days or weeks for your body to fully adjust. But shifting your circadian rhythm gradually will give you the best chance of sticking to your new schedule, without sacrificing sleep or daytime energy. 

In a rush and want to reset your sleep schedule overnight? Focus on sleep hygiene habits. These habits will give you the best chance of falling asleep when your body naturally wants to.  

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What Are Circadian Rhythm Sleep Disorders?

Circadian rhythm sleep disorders are disorders that affect your circadian rhythm, and therefore the timing of your sleep.  

They include: 

• Delayed sleep-wake phase disorder: When your sleep is abnormally late compared to the light-dark cycle.
• Advanced sleep-wake phase disorder: When your sleep is abnormally early compared to the light-dark cycle.
• Shift work sleep disorder: When you work shifts and feel sleepy at work and alert when you need to sleep. 
• Jet lag disorder: When you travel to a different time zone and your body takes a while to adjust to the new timing. 
• Irregular sleep-wake rhythm disorder: When your sleep schedule doesn’t have a pattern and you take several naps over a 24-hour period. This disorder is often seen in older individuals and those with Alzheimer’s or a brain injury. 

The best way to fix a circadian rhythm sleep disorder is to speak to your doctor or a sleep specialist. They’ll be able to recommend lifestyle changes, like improving your sleep hygiene, and treatments, like light therapy and melatonin.  

Reset Your Circadian Rhythm with RISE 

If you’re suffering from low daytime energy and trouble sleeping, it may be time to reset your circadian rhythm. Shift your sleep-wake times gradually, get light early in the morning and during the day, and then avoid it before bed. 

Tuning into your circadian rhythm isn’t exactly second nature — and this is where the RISE app can help. 

RISE predicts the timing of your circadian rhythm based on algorithms, your recent sleep times, and your inferred light exposure. The app will then show you a visualization of what your circadian rhythm looks like, so you can sync up your daily life to it and work to shift it earlier or later, depending on your lifestyle and work schedule. 

To help make that happen, RISE can tell you when to do 20+ sleep habits. These sleep hygiene habits will give you the best chance of meeting your sleep need with natural healthy sleep and staying in sync with your circadian rhythm. 

Resetting your circadian rhythm is a gradual process, but each small step you take to sync up and get more sleep can have big benefits. In fact, 80% of RISE users feel more energy within five days.

What Is A Circadian Rhythm And How To Reset Your Body Clock?

Humans have clock genes that make the body tick like a well-oiled machine. Learn about your circadian rhythm and how it affects your health and disease risks.

A circadian rhythm is a 24-hour biological clock that affects your sleep, digestion, and metabolism. When your circadian rhythm is disrupted, it can even increase your disease risks.

The circadian rhythm is a body clock that organises all the biological processes necessary for life. It is dictated by clock genes that trigger essential metabolic activities, like storing energy, transporting oxygen, getting rid of waste, and releasing hormones and neurotransmitters.

Table of contents

• What is a circadian rhythm?
• How the circadian cycle works
• Do you need to reset your body clock?
• Circadian rhythm and health
• How to fix your sleep schedule

Even though you can’t see or feel this clock, circadian health is essential for your health and wellbeing. In this article, you’ll discover what happens when the cycle rhythm is disrupted, how to reset your body clock, and how to fix your sleep schedule.

What is a circadian rhythm?

How does your body know what time it is? (Ted Ed video)

The circadian rhythm is a 24-hour clock that dictates millions of invisible metabolic processes that keep the body alive. It determines digestive rhythms, fat burning and fat storage, sleeping patterns, and much more. This biological rhythm is run by clock genes that signal when each process should take place.

Approximately 20% of genes turn on and off during the 24-hour cycle.

Going to bed late, playing with your phone at midnight, eating late in the evening, and working night shifts are all factors that can shift your circadian cycle. Scientific evidence now indicates that circadian rhythm disruptions are associated with serious, but preventable, chronic diseases like diabetes type II, heart disease, obesity, stroke, and cancers.

How the circadian cycle works

A circadian rhythm chart can help you optimise your daily activities

The circadian rhythm is made up of a set of clocks and a central “master clock”, called the suprachiasmatic nucleus (SCN). The SCN is located in the hypothalamus, the part of the brain responsible for regulating stress, reproduction, and growth hormones. It also indirectly impacts sleep hormones.

The body’s clock contains about 20,000 cells, which are located just above the intersection of the optic nerves. The cycle rhythm is set by signals from special melanopsin cells in the retina in response to light exposure. Blue light (from bright daylight, phone screens, and TVs) has the strongest effect on melanopsin receptors, followed by green and red light.

The circadian rhythm reacts to light: it wakes you up, and it puts you to sleep by triggering cascades of chemical events in your brain.

Body clock genes have been discovered in nearly every organ of the human body. These genes turn on and off at predictable times, switching on and shutting down the production of proteins that perform essential functions within the body’s cells.

Interestingly, studies show that blind mice and blind people still have active melanopsin receptors that regulate their biological clock. This helps to explain why patients suffering from blindness can “sense” light, even if they can’t see it.

☝Find out more about your genes☝ Take the Atlas DNA Test to explore how your genetic make-up affects your health and wellbeing.

Do you need a body clock reset?

Sleeping at irregular times, using devices, eating late at night, and other pernicious habits displace the cycle rhythm. When a person’s biological cycle isn’t on schedule, it causes a wide range of minor health issues that can affect everyday life.

Low energy, mood swings, food cravings, weak immunity, and having trouble losing weight are common side effects of circadian disruption according to Professor Satchidananda Panda, author of the Circadian Code.

Circadian rhythm and digestion

The digestive system secretes the most gastric juices, enzymes, and hormones in the first half of the day. This activity reduces as the afternoon progresses into evening. These molecules are all essential for healthy digestion, which is why eating late at night can cause indigestion.

Circadian rhythm and sleep

Your circadian rhythm is run by clock genes

At night, the circadian rhythm is focused on putting the body to sleep, removing waste products, and repairing tissues from the wear-and-tear of daytime activities. In fact, sleep is the only time for the brain to remove the waste products of chemical reactions.

When you mess with your sleep schedule, or deprive yourself of sleep, you impair the brain’s ability to operate at maximum efficiency.

Circadian rhythm and disease

Living out of sync with the body’s circadian rhythm over the short and long term is associated with serious, chronic, and preventable diseases that affect the body’s metabolism, according to a 2016 systematic review on the “Interaction between circadian rhythms and stress”.

In one referenced study, the human participants with impaired circadian rhythm function had “higher blood glucose and insulin levels as well as elevated blood pressure, which are markers for metabolic and cardiovascular disease.”

The study’s summary of its effects on night shift workers demonstrated that such professionals have “a higher incidence of obesity, diabetes type II and related metabolic disturbances along with hypertension (high blood pressure), coronary heart disease, and ischemic stroke”.

How to fix your sleep schedule

Light and darkness are the main determinants in circadian rhythm. When daylight or screen light is detected by your eyes, it sends signals to the suprachiasmatic nucleus, which regulates all the clock genes in your body.

To reset your body clock, you need to put yourself on a schedule that respects your body’s metabolic rhythm. While this may be impossible for night shift workers, it is an achievable goal for people with day jobs.

• Go to bed and get up at the same time every day.
• Turn off TV screens, phones, and tablets 1-2 hours before bed.
• Eat your biggest meal early in the day when digestive juices are highest.
• Stay away from caffeinated beverages in the afternoon and evening.
• Cut down on alcohol at night because it affects sleep quality.
• Stop eating at least 3 hours before bed to avoid indigestion.
• Get blackout curtains and dim light bulbs for your bedroom.

• [Sachin Panda, The Circadian Code]
• Koch C.E. et al., Interaction between Circadian Rhythm and Stress 2017
• S. Panda et al., Coordinated Transcription of Key Pathways in the Mouse by the Circadian Clock
• Blue light has a dark side
• Circadian rhythms fact sheet
• Thomas C. Erren et al., Shift Work and Cancer 2010
• Bennett J.E. et al. (2018). NCD Countdown 2030: worldwide trends in non-communicable disease mortality and progress towards Sustainable Development Goal target 3.4
• NHS Prevalence, Achievements and Exceptions workbooks 2016

what it is and how to get enough sleep

We are controlled by circadian rhythms. This biological clock affects how we sleep, expend energy, and digest food. Let’s figure out how to make friends with them.

Our sleep schedule and activity schedule, and well-being in general, are subject to daily cycles. Therefore, sometimes, no matter what we do, it can be difficult to get ready for work in the afternoon or force ourselves to go to the gym in the morning.

In this article, we will figure out how to make friends with your biological clock in order to use it to your advantage.

Contents

• 1. What are circadian rhythms
• 2. How Our Internal Clock Works
• 3. How circadian rhythms affect our health
• 4. Why it is dangerous to disrupt circadian rhythms
• 5. How to reset your internal clock
• 6. Note

What are circadian rhythms

Circadian rhythms are the human biological clock. They set the rhythm for all vital processes in the body. The body clock is determined by genes that start and stop metabolic processes, such as storing energy or releasing hormones.

24 hours

how long does one biological clock cycle last on average

About 20% of all our genes are “turned on” and “off” during one complete cycle.

The main mechanism of the biological clock is the suprachiasmatic nucleus (SCN) of the hypothalamus. This part of the brain is responsible for the response to stress, sexual behavior, coordination of actions and other important functions.

This nucleus receives information from light-sensitive cells of the retina and other receptors and based on it synchronizes the work of biorhythms .

Approximately so biological processes follow each other during the day

Also, the suprachiasmatic nucleus informs the pineal gland and the endocrine gland when it is time to produce the sleep hormone melatonin.

Melatonin concentration increases in the evening, peaks at night and decreases during the day.

A with another important hormone, cortisol , the reverse story.

Photo by Jamie Street / Unsplash

Its concentration rises in the morning, when we need to be alert, and decreases in the evening, when we start to feel sleepy.

How our internal clock works

The genes responsible for the operation of the internal clock are called period and timeless . Their activity fluctuates throughout the day and is regulated by a feedback loop mechanism. As soon as the level of proteins encoded by these genes reaches a certain level, the synthesis of these proteins stops. The level drops – synthesis resumes.

Sleep and wakefulness are affected by light

Light and its absence are the main, though not the only, regulators of circadian rhythms.

Cold blue light from office lamps, computer screens, TVs and smartphones disrupts these rhythms. As a result, the body “thinks” that daylight hours are in full swing. Red and green light also negatively affect the course of the internal clock.

Circadian rhythms are “turned on” and “turned off” by light. Bright artificial light triggers cascades of chemical reactions and disrupts the correct daily routine.

Human circadian rhythms are not a separate organ, they cannot be seen or felt. But they are necessary for health and normal life – and persist even in many blind people.

Photo by Max van den Oetelaar / Unsplash

If you watch TV shows at night, eat late and heavy dinners, work the night shift and go to bed at dawn, the coordinated work of genes and circadian rhythms is disrupted. Some metabolic processes start later than usual, while others stop altogether.

How Circadian Rhythms Affect Our Health

Night shifts can increase cancer risk – disrupted circadian rhythms make it harder for the body to prevent tumor formation.

The International Agency for Research on Cancer has even classified shift work as a carcinogen.

Working with a constant night schedule rather than a hopping schedule may be less dangerous in this regard.

Photo by Kartabya Aryal / Unsplash

Scientists have linked circadian rhythm disturbances to serious but preventable diseases: type 2 diabetes, cardiovascular disease, obesity, stroke and cancer.

To understand how these diseases develop, we need to look at what happens when we break our sleep hygiene.

• How circadian rhythms affect digestion

The gastrointestinal tract produces the most enzymes, gastric juice and related substances in the first half of the day.

Therefore, it is advisable to have a hearty breakfast, but have a light supper.

Also in the morning the peristalsis works most actively. If you eat heavily at night and wake up late, the risk of constipation, colic, bloating and indigestion increases, because the digestion process slows down.

Taking care of your digestive health is easier with the Atlas Microbiota Test. You will learn how diverse the composition of the bacteria in your intestines, whether there are enough beneficial bacteria, and how the microflora protects you from diseases. How circadian rhythms affect the brain

Photo by Konstantine Trundayev / Unsplash

This fluid removes metabolic products, including toxic compounds that impair memory function. Also, during sleep, myelin sheaths are actively restored – they are needed to transmit signals between neurons.

Sleep phase disruption interrupts these important processes.

As a result, we wake up tired, lethargic and not ready for serious intellectual work.

If you constantly ignore your biological rhythms, this can lead to neuropsychiatric disorders.

• How circadian rhythms affect disease risk

Insomnia, lack of sleep and poor sleep quality lead to hypertension and insulin resistance, which increases blood glucose levels. These symptoms signal metabolic disorders and diseases of the cardiovascular system.

Studies show that people who work night shifts are more likely to suffer from obesity, type 2 diabetes and hypertension.

The risk of developing these diseases is also increased in people with disturbed circadian rhythms.

Why disrupting circadian rhythms is dangerous

Poor sleep quality brings other, less obvious problems. A sleepy person easily gains weight and hardly loses it.

He crave sweets and junk food more often than healthy food, because the body tries to compensate for the lack of energy with cravings for simple carbohydrates.

Also, if jet lag becomes more difficult to fall asleep and wake up, addiction to caffeine develops.

Photo by Nathan Dumlao / Unsplash

I want to sleep as long as possible, but sleep stops replenishing my strength.

The risk of depression increases, there are mood swings during the day and bursts of negative emotions. And the body becomes more vulnerable to diseases and infections.

How to reset your internal clock

The good news is that a broken body clock can be repaired.

Together with the correct daily routine, you will return to productivity and healthy sleep. Restoring your circadian rhythms and daily routine doesn’t mean going to bed right after sunset, especially if you’re a night owl.

The main thing is to avoid artificial light and fall asleep during the time period when melatonin is produced, that is, from 12 am to 4 am.

Avoiding gadgets an hour or two before bed will help you fall asleep easier. Also in the evening it is worth turning on lamps with warm dimmed light instead of bright fluorescent lamps. To restore the sleep pattern, you need to go to bed every day at about the same time, even if it is a day off.

If you often feel tired and distracted during the day and do not sleep well, you may have thrown off your biological clock. Here’s what will help bring everything back to normal:

• If you really need to check social networks before going to bed or watch a movie on your tablet, turn on the night mode – with it, the backlight becomes yellowish and less bright.
• Switch from visual content to audio before bed: listen to podcasts and audiobooks.
• Avoid alcohol in the late evening – it impairs the quality of sleep.
• Go to bed slightly hungry.
• Buy heavy, light-blocking curtains and open them as soon as you wake up.
• In the afternoon, choose decaffeinated drinks.
• Use ear plugs and a sleep mask if outside noises or street lights interrupt your sleep.

Genetics can also influence sleep patterns: for example, insomnia can be inherited. To identify the genetic predisposition to insomnia and the characteristics of caffeine metabolism, you can use the Atlas Genetic Test.

More interesting articles about sleep on the Atlas blog:

• Sleep, diet, and giving up your smartphone: habits that will make you happier
• Night work: dangers and health benefits
• Sleep and microbiota: how appetite and digestion are related to sleep quality

• Sachin Panda, The Circadian Code
• Koch C.E. et al., Interaction between Circadian Rhythm and Stress 2017
• S. Panda et al., Coordinated Transcription of Key Pathways in the Mouse by the Circadian Clock
• Blue light has a dark side
• Circadian rhythms fact sheet
• Thomas C. Erren et al., Shift Work and Cancer 2010
• Bennett J.E. et al. (2018). NCD Countdown 2030: worldwide trends in non-communicable disease mortality and progress towards Sustainable Development Goal target 3.4
• NHS Prevalence, Achievements and Exceptions workbooks 2016
• The role of sleep and wakefulness in myelin plasticity
• Night shift work, short sleep and obesity

Human circadian rhythms — what are they in simple words, how to restore them

Back in 2017, the Nobel Prize in Physiology was awarded to scientists who studied the so-called “circadian rhythms” — the human biological clock that controls the work of almost every system in our body. Today we will tell you about what these mysterious biorhythms are and how a person can normalize his sleep without resorting to pills.

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What are circadian rhythms?

Whether you are an owl or a lark that rises day after day with sunrise, the body’s habit of sleeping at certain times is regulated by the so-called circadian rhythms . This internal clock controls almost every aspect of our health, from appetite and sleepiness to cell division, hormone production, and cardiovascular health. Scientists are optimistic, because one day medicine has every chance to develop drugs or therapies that regulate the body’s circadian rhythms – and problems with lack of sleep will become a thing of the past.

By themselves, circadian rhythms are a kind of biorhythms, cycles that last 24 hours, work in the background and affect the basic functions of the body.

What influences our internal clock?

First, they affect the production of relaxation hormones before going to bed and wakefulness hormones upon awakening. But since circadian rhythms include all phenomena in the human body that repeat after 24 hours, they are also responsible for the correct functioning of many other processes:

Metabolism

One of the functions that circadian rhythms influence is the regulation of hormonal cycles of leptin, ghrelin, insulin, growth hormone, and hormones responsible for metabolism and macronutrient utilization throughout the day. That is why eating, like sleeping, is necessary at the same time so that the body has time to produce the necessary elements in time.

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Mental health

The area of ​​responsibility of circadian rhythms, which is directly related to sleep. The fact is that when you wake up, the body produces cortisol, a hormone responsible for combating stress and cognitive abilities. Disruption of this process can cause mental disorders, depression, neurodegenerative diseases, and dementia.

Immune system

Proper functioning of the immune system is directly related to circadian rhythms. Immune cells are produced regularly, according to life cycles. For example, every day our body synthesizes cytokines, chemokines, and cytolytic factors.

Body temperature

It would seem that every person knows his normal value on a thermometer, which remains unchanged when feeling well. However, we do not notice how during the day the thyroid gland and hypothalamus, depending on the phase of the circadian rhythm, slightly change our body temperature. Of course, the difference is small and imperceptible, but very important for the proper functioning of the body.

Circadian Rhythm Diagram – How Our Internal Clock Works

Almost every cell in the human body has a molecular clock. This manifests itself in such a way that approximately every 24 hours certain clock proteins interact with each other in a kind of slow dance. During the day, this process leads to the timely activation of certain genes that control a variety of processes, including the release of certain hormones into the blood. Melatonin is a hormone that stimulates sleep, and its concentration in the blood also depends on gene activity.

Why are heart attacks and strokes two to three times more common in the early morning? Because the internal clock is programmed to increase blood pressure at this time to help the body wake up. Why do children grow up in their sleep? Because growth hormone is produced in the human body only once a day, precisely during the phase of night sleep (therefore, it is not worth abusing afternoon naps at this age). As a result, the harmonious work of all body systems is somehow connected with this clock. That is why disturbances in the rhythm of sleep and wakefulness increase the risk of obesity, the development of chronic diseases and even cancer, not to mention a general deterioration in well-being.

The timing of your meal can also affect your health: when you eat is often much more important than what you eat. A few years ago, researchers analyzed this process by feeding mice, which are usually nocturnal. They were put on a high-fat diet, and the result was immediate: those who ate during active times of the day remained in shape; but those who like to nibble something day and night almost immediately began to suffer from overweight and fell ill.

Where do owls and larks come from?

Each person has their own internal circadian rhythms. It is more comfortable for someone to get up at 6 am and go to bed at 10 pm, while someone begins to feel alert only by noon and cannot fall asleep until 2 am. These features are called chronotypes and are transmitted to a person at the genetic level.

Scientists distinguish three chronotypes:

• Larks – an early type. People who have peak activity in the first half of the day;
• Owls late type. Those who are more comfortable working in the afternoon or evening;
• Pigeons – medium type. It is believed that this chronotype is the most comfortable for modern life. They don’t get up as early as larks, but they don’t stay up late like owls either.

It is important to know your chronotype and live according to it in order to plan your schedule effectively.

Darya Lebedeva, sleep doctor, therapist, endocrinologist says:

The opinion that following circadian rhythms means going to bed before 12 at night and getting up as early as possible is a myth imposed by society. People have individual characteristics that are inherited. Therefore, if, for example, owls always get up and go to bed at the same time with a period of 24 hours, this will be much more beneficial for them than if they get up at 6 in the morning like larks.

If a person goes to bed and wakes up at his own individual time while maintaining the required norm of hours of sleep, the body will be properly adjusted. The hormones responsible for sleep and relaxation will be synthesized and prepare the body for sleep, and in the morning the hormones responsible for alertness will be properly produced.

If you do not follow these rules – go to bed and get up at different times, “sleep off” on weekends, then the body will start to get confused. There will be drowsiness, a feeling of nausea, an increased risk of obesity, metabolic syndrome, diabetes, strokes, heart attacks, oncological and infectious diseases. In addition, the quality of life will suffer – a person who does not follow his circadian rhythms will always want to sleep and lose productivity during the day.

Why do circadian rhythm disorders occur?

The causes of circadian rhythm disorders can be very different, for example:

• Delayed sleep phase syndrome. A disorder in which a person cannot normalize their circadian rhythms and go to bed earlier, even if they want to sleep;
• Sleep phase advance syndrome. The reverse story, when a person falls asleep and wakes up earlier than the body needs. Most common in older people;
• Time zone change syndrome. Occurs in people who constantly travel and move around the world. At some point, due to the frequent change of time zones, the body begins to get confused and a disorder of circadian rhythms occurs;
• Shift work. Often, people with flexible schedules have trouble sleeping because they have to go to sleep and wake up at different times and sacrifice their natural circadian rhythms to accommodate their work schedule.

What is the danger of internal clock failure?

Since circadian rhythms are responsible for a significant number of systems in our body, their failure can lead to a large number of disorders and diseases:

• Oncology – when circadian rhythms are disrupted, it becomes more difficult for the body to prevent the formation and development of tumors;
• Gastrointestinal disorder – disruption of circadian rhythms can lead to improper production of gastric juice and related substances;
• Diseases of the brain – during healthy sleep, the brain is cleansed with the help of cerebrospinal fluid, and disturbance of sleep phases interrupts this process;
• Diseases of the cardiovascular system – lack of sleep and disruption of circadian rhythms lead to hypertension and the development of insulin resistance;
• Obesity – due to lack of sleep, the body wants to compensate for the lack of energy. A person begins to abuse simple carbohydrates, which leads to overweight;
• Vulnerability to infections – when the circadian rhythm is disturbed, the body simply becomes weaker, which makes it more difficult for it to fight viruses.

How to set your biological clock

Our biological rhythm is “coded” individually, with most people falling into a 24-hour cycle. However, there are those whose internal routine is out of sync – for example, the rhythm that has become so popular “ owls “. Scientists believe that in 1 in 75 people, owl mode is caused by a mutation in the CRY1 protein, which delays sleepiness until the early hours of the morning. This is not only complicated by the fact that “owls” have to get up early and do everyday things, but also by the fact that due to desynchronization, the cycle becomes elongated and the body is constantly in a state of intense, unhealthy wakefulness. But this is a rare genetic mutation, and for everyone else, a simple and effective therapy can help improve their condition.

The biological clock is, of course, synchronized with the brain. The light our eyes catch helps maintain the day/night cycle, which is why when you travel to a different time zone, your internal clock no longer matches the solar cycle, and it takes about a week to adjust. In everyday life, the worst enemy of the internal clock is bright artificial light at night, which literally disorientates the body’s systems. Scientists have found that even the usual reading of e-books at night for several hours can cause a deterioration in sleep and make you feel worse the next day.

Fortunately, these effects can be minimized with “ Light Hygiene “. During the day, you should provide your eyes with a sufficient amount of bright light, but with the onset of twilight, it is better to minimize its effect. This simple step will allow the circadian clock to synchronize with the natural 24-hour cycle, which promotes healthy and sound sleep.

Things you can do to get your circadian rhythm back on track:

• Avoid using gadgets before bed. If this cannot be avoided, enable night mode on your devices;
• Switch to audiobooks or podcasts instead of movies and TV shows;
• Do not drink alcohol in the evening;
• Do not overeat before going to bed, it is better to go to bed slightly hungry;
• Don’t skimp on a good mattress and sleeping pillow;
• Buy heavy, light-blocking curtains. It is important that upon awakening they must be opened immediately;
• Avoid caffeinated drinks in the afternoon;
• If you are disturbed by extraneous sounds or noise from the street, use a sleep mask and earplugs.

Future and future research

The longer scientists study circadian rhythms, the more likely they are to develop effective methods for harmonizing sleep and wakefulness. Now, most research is focused on studying the complex molecular mechanisms that regulate circadian rhythms: in particular, geneticists analyze the interaction of CRY1 with other “clock” proteins in the hope of understanding exactly how mutations damage the biological clock. They have already figured out that the mutated protein keeps bonding with its partners longer than it should, just like an insecure dancer in a more experienced group. A delay in the synchronization of this pair, like a chain reaction, causes a malfunction in the work of other systems, which are forced to adapt to the disturbed rhythm.

Given the complex and still not fully understood nature of the bioclock, it is safe to say that many other genes influence circadian rhythms. This is good news, because in this case, even people with a disturbed genome can be helped by pharmacology, maximizing the beneficial effect and minimizing the negative effects of drugs on the body as a whole. This is the trouble with modern drugs that raise blood pressure or lower cholesterol levels – for every beneficial effect there are a dozen unpleasant side effects.

Perhaps in the near future there will even be special gadgets that can monitor the state of a person’s rhythms in real time and warn about a broken mode in advance.