Anyone who has suffered from jet lag or struggled after turning the clock forward or back an hour for daylight saving time knows all about what researchers call your biological clock, or circadian rhythm – the “master pacemaker” that synchronizes how your body responds to the passing of one day to the next.
This “clock” is made up of about 20,000 neurons in the hypothalamus, the area near the center of the brain that coordinates your body’s unconscious functions, like breathing and blood pressure. Humans aren’t the only beings that have an internal clock system: All vertebrates – or mammals, birds, reptiles, amphibians and fish – have biological clocks, as do plants, fungi and bacteria. Biological clocks are why cats are most active at dawn and dusk, and why flowers bloom at certain times of day.
Circadian rhythms are also essential to health and well-being. They govern your body’s physical, mental and behavioral changes over each 24-hour cycle in response to environmental cues like light and food. They’re why more heart attacks and strokes occur early in the morning. They’re also why mice that are missing their biological clocks age faster and have shorter lifespans, and people with a mutation in their circadian clock genes have abnormal sleep patterns. Chronic misalignment of your circadian rhythm with external cues, as seen in night-shift workers, can lead to a wide range of physical and mental disorders, including obesity, Type 2 diabetes, cancer and cardiovascular diseases.
In short, there is ample evidence that your biological clock is critical to your health. And chronobiologists like me are studying how the day-night cycle affects your body to better understand how you can modify your behaviors to use your internal clock to your advantage.
How biological rhythms affect your health
Your biological clock affects your health by regulating your sleep-wake cycles and fluctuations in blood pressure and body temperature. It does this primarily by syncing your endocrine system to environmental light-dark cycles so that certain hormones are released in certain amounts at certain times of day.
The pineal grand in your brain, for example, produces melatonin, a hormone that helps regulate sleep in response to darkness. Doctors advise reducing exposure to artificial blue light from electronic devices before bedtime because it can disrupt melatonin secretion and sleep quality.
Your circadian rhythm also affects your metabolism. Among other things, sleep helps you regulate leptin, a hormone that controls appetite. Your leptin levels fluctuate throughout the day according to a rhythm set by your circadian clock. Insufficient or irregular sleep can disrupt leptin production, which can make us hungrier and lead to weight gain.
Your hormones fluctuate rhythmically over the course of the day. The stress hormone cortisol typically peaks in the morning, while the sleep hormone melatonin typically peaks in the night. Pikovit44/iStock via Getty Images Plus
In recent years, researchers have discovered even more ways your circadian clock can affect your health. For example, there is now research suggesting that eating at set times of day, or time-restricted feeding, can prevent obesity and metabolic diseases. Depression and other mood disorders may also be linked to dysfunctional circadian control that lead to changes in how your genes are expressed.
The time of day when you take your medicine can also affect how well it works and how severe any side effects might be. Likewise, your biological clock is a potential target for cancer chemotherapies and anti-obesity treatments.
And finally, even your personality might be shaped by whether your internal clock make you a “morning person” or a “night person.”
Getting the most out of exercise
Circadian clocks also provide a potential answer to when is the best time of day to maximize the benefits of physical exercise.
To study this, my colleagues and I collected blood and tissue samples from the brains, hearts, muscles, livers and fat of mice that exercised either before breakfast in the early morning or after dinner in the late evening. We used a tool called a mass spectrometer to detect approximately 600 to 900 molecules each organ produced. These metabolites served as real-time snapshots of how the mice responded to exercise at specific times of day.
We stitched these snapshots together to create a map of how exercise in the morning versus evening affected each of the mice’s different organ systems – what we called an atlas of exercise metabolism.
Using this atlas, we saw that time of day affects how each organ uses energy during exercise. For instance, we found that early morning exercise reduced blood glucose levels more than late evening exercise. Exercise in the late evening, however, allowed the mice to benefit from energy they stored from their meals and increased their endurance.
Of course, mice and humans have many differences along with their similarities. For one, mice are more active at night than during the day. Still, we believe that our findings could help researchers better understand how exercise affects your health and, if timed appropriately, can be optimized based on time of day to meet your personal health goals.
Getting along with your biological clock
I believe that the field of chronobiology is growing, and we will produce even more research providing practical applications and insights into health and well-being in the future.
In my own work, for example, a better understanding of how exercising at different times of day affects your body could help tailor exercise plans to maximize specific benefits for patients with obesity, Type 2 diabetes and other diseases.
There is still much to learn about how your circadian clock works. But in the meantime, there are some tried and true ways people can synchronize their internal clocks for better health. These include regular exposure to sunlight to trigger the endocrine system to produce vitamin D, staying active during the day so you fall asleep more easily at night and avoiding caffeine and reducing your exposure to artificial light before bedtime.
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Shogo Sato receives funding from the Brain & Behavioral Research Foundation (NARSAD Young Investigator Grant, 28681) and start-up funds from Texas A&M University.
Myth. When it comes to sleep no-nos, experts say this is a big one. Lying in bed, even with your eyes closed, for more than 15 to 20 minutes is one of the worst things you can do because it will train your brain to associate the bed with a lack of sleep. It can lead to chronic insomnia, Michael Grandner, a clinical psychologist and sleep expert, told CNN in an earlier interview.
"It's counterintuitive, but spending time in bed awake turns the bed into the dentist's chair," said Grandner, who directs the sleep and heath research program at the University of Arizona and the Behavioral Sleep Medicine Clinic at the Banner-University Medical Center in Tucson, Arizona.
"You want the bed to be like your favorite restaurant, where you walk in and you start getting hungry, even if you just recently ate," he added. "You want the bed to do that for sleep."
Myth. When it comes to sleep no-nos, experts say this is a big one. Lying in bed, even with your eyes closed, for more than 15 to 20 minutes is one of the worst things you can do because it will train your brain to associate the bed with a lack of sleep. It can lead to chronic insomnia, Michael Grandner, a clinical psychologist and sleep expert, told CNN in an earlier interview.
"It's counterintuitive, but spending time in bed awake turns the bed into the dentist's chair," said Grandner, who directs the sleep and heath research program at the University of Arizona and the Behavioral Sleep Medicine Clinic at the Banner-University Medical Center in Tucson, Arizona.
"You want the bed to be like your favorite restaurant, where you walk in and you start getting hungry, even if you just recently ate," he added. "You want the bed to do that for sleep."
That's a fact. Banning smartphones (or any electrical device that emits blue light) from the bedroom an hour or so before bed and all through the night is a must for good slumber, experts say. Light tells the body to stop producing melatonin, the body's natural sleep aid, and studies have shown that blue light is especially toxic to sleep.
So when you get out of bed after 20 minutes of sleeplessness, avoid bright light, watching TV or checking social media. Instead, keep the lights dim and do something mindless, such as folding socks. Better yet, try doing one of these tricks to relax your mind and ready yourself for sleep.
That's a fact. Banning smartphones (or any electrical device that emits blue light) from the bedroom an hour or so before bed and all through the night is a must for good slumber, experts say. Light tells the body to stop producing melatonin, the body's natural sleep aid, and studies have shown that blue light is especially toxic to sleep.
So when you get out of bed after 20 minutes of sleeplessness, avoid bright light, watching TV or checking social media. Instead, keep the lights dim and do something mindless, such as folding socks. Better yet, try doing one of these tricks to relax your mind and ready yourself for sleep.
That's a myth that used to be a fact "in the olden days," Dasgupta said.
"Now the data shows that exercise at any time is better than not exercising due to all the medical benefits, and it helps with stress reduction, which aids sleep," he said. "The data about not exercising at night is when you're doing extreme workouts like Olympic athlete-type exercises."
People who exercised for 35 minutes right before bed slept as well as they did on nights when they didn't exercise at all, a 2011 study found. If working out at night does affect your sleep, experts suggest exercising early in the evening so your heart rate and body temperature can return to normal before you hit the hay.
"If you ask me when's the perfect time to exercise, I think it's gonna be in the morning and outside in daylight. It resets the circadian rhythm and starts the day off with vigor," Dasgupta said. "But if nighttime exercise is best for you, that's fine."
That's a myth that used to be a fact "in the olden days," Dasgupta said.
"Now the data shows that exercise at any time is better than not exercising due to all the medical benefits, and it helps with stress reduction, which aids sleep," he said. "The data about not exercising at night is when you're doing extreme workouts like Olympic athlete-type exercises."
People who exercised for 35 minutes right before bed slept as well as they did on nights when they didn't exercise at all, a 2011 study found. If working out at night does affect your sleep, experts suggest exercising early in the evening so your heart rate and body temperature can return to normal before you hit the hay.
"If you ask me when's the perfect time to exercise, I think it's gonna be in the morning and outside in daylight. It resets the circadian rhythm and starts the day off with vigor," Dasgupta said. "But if nighttime exercise is best for you, that's fine."
Who doesn't believe this one? Sadly, the science says we're wrong. We may feel better after sleeping in on a Saturday or Sunday morning, but it will be to the detriment of our overall sleep health, experts say. By changing your wake-up time and bedtime on weekends (or day to day), your sleep rhythms aren't predictable, which can alter the body's circadian rhythm.
"You want to build a reliable rhythm, much like the drummer counting the beat for the band," Grandner said. "By controlling when you wake up and go to bed, you're setting the beat."
Overcome this myth by going to bed and getting up at the same time each day, even on weekends, vacations or after a night of poor sleep.
"The brain likes regularity and predictability," he added. "Waking up at the same time every day and then adding light and movement as soon as you wake up will set your other rhythms for the day and give you increased energy and mood."
Who doesn't believe this one? Sadly, the science says we're wrong. We may feel better after sleeping in on a Saturday or Sunday morning, but it will be to the detriment of our overall sleep health, experts say. By changing your wake-up time and bedtime on weekends (or day to day), your sleep rhythms aren't predictable, which can alter the body's circadian rhythm.
"You want to build a reliable rhythm, much like the drummer counting the beat for the band," Grandner said. "By controlling when you wake up and go to bed, you're setting the beat."
Overcome this myth by going to bed and getting up at the same time each day, even on weekends, vacations or after a night of poor sleep.
"The brain likes regularity and predictability," he added. "Waking up at the same time every day and then adding light and movement as soon as you wake up will set your other rhythms for the day and give you increased energy and mood."
Some people have no problem falling asleep mid-sentence; for others, they can read hundreds of sentences in bed and still not feel tired. Not being able to fall asleep is a condition called insomnia, a common sleep disorder that impacts between 10% and 30% of adults. Sunday Citizen compiled recommendations and best sleeping practices for those struggling with insomnia, citing a collection of medical and expert reports.
Insomnia makes it difficult to fall asleep or remain asleep, and without enough rest, it’s natural to be tired, cranky, and foggy for the rest of the day. Contrary to popular belief, this disorder is not determined by the number of hours of sleep or how much time it takes to fall asleep; everyone is different in their sleep needs and the amount of time it takes to fall asleep.
Insomnia comes in a variety of forms, each with its own set of symptoms, sleep issues, and length of occurrence. Some of the most common causes of insomnia are stress, travel, lifestyle habits, and eating late. Temporary insomnia typically lasts less than a week. When it’s caused by stressful situations, it usually goes away after the event is resolved. Short-term insomnia lasts one to three weeks, but long-term or chronic insomnia lasts longer.
According to a 2018 study carried out by researchers at the Perelman School of Medicine at the University of Pennsylvania, 1 in 4 people in the United States experience insomnia each year; about 3 in 4 of these people recover fully without developing chronic insomnia. This study shows the prevalence of poor sleep. However, by adopting habits that promote better sleep, some of the factors that cause insomnia can be managed.
megaflopp // Shutterstock
Some people have no problem falling asleep mid-sentence; for others, they can read hundreds of sentences in bed and still not feel tired. Not being able to fall asleep is a condition called insomnia, a common sleep disorder that impacts between 10% and 30% of adults. Sunday Citizen compiled recommendations and best sleeping practices for those struggling with insomnia, citing a collection of medical and expert reports.
Insomnia makes it difficult to fall asleep or remain asleep, and without enough rest, it’s natural to be tired, cranky, and foggy for the rest of the day. Contrary to popular belief, this disorder is not determined by the number of hours of sleep or how much time it takes to fall asleep; everyone is different in their sleep needs and the amount of time it takes to fall asleep.
Insomnia comes in a variety of forms, each with its own set of symptoms, sleep issues, and length of occurrence. Some of the most common causes of insomnia are stress, travel, lifestyle habits, and eating late. Temporary insomnia typically lasts less than a week. When it’s caused by stressful situations, it usually goes away after the event is resolved. Short-term insomnia lasts one to three weeks, but long-term or chronic insomnia lasts longer.
According to a 2018 study carried out by researchers at the Perelman School of Medicine at the University of Pennsylvania, 1 in 4 people in the United States experience insomnia each year; about 3 in 4 of these people recover fully without developing chronic insomnia. This study shows the prevalence of poor sleep. However, by adopting habits that promote better sleep, some of the factors that cause insomnia can be managed.
Various factors cause insomnia, many of which can be addressed through lifestyle changes. Other factors are linked to medical issues that an individual may not be aware they have, such as disrupted breathing due to sleep apnea. Consulting a doctor will rule out underlying medical problems that may be interfering with healthy sleep.
The diagnosis of insomnia often involves a physical exam for symptoms of medical issues linked with insomnia. Doctors also review sleep-wake patterns and the level of daytime sleepiness to identify insomnia and its cause. If the cause can’t be clearly identified, a sleep study is performed to track and record a wide range of bodily functions. This study paints a clearer picture of the underlying cause.
Erickson Stock // Shutterstock
Various factors cause insomnia, many of which can be addressed through lifestyle changes. Other factors are linked to medical issues that an individual may not be aware they have, such as disrupted breathing due to sleep apnea. Consulting a doctor will rule out underlying medical problems that may be interfering with healthy sleep.
The diagnosis of insomnia often involves a physical exam for symptoms of medical issues linked with insomnia. Doctors also review sleep-wake patterns and the level of daytime sleepiness to identify insomnia and its cause. If the cause can’t be clearly identified, a sleep study is performed to track and record a wide range of bodily functions. This study paints a clearer picture of the underlying cause.
Sleep journals are a tool doctors can use to find out how much and how well a patient sleeps. In these journals, sleep patterns are recorded for a few weeks to identify things that may be interfering with a patient’s sleep. Sleep journals can be as simple as a sheet of paper with a template guiding patients on what information to fill out.
For patients who prefer not to use paper, phone apps are available to keep track of sleep and other vital information doctors might need. Because the information required for different forms of insomnia differs, it’s best to consult a doctor about what to include in the journal and the duration of tracking sleep.
Maria Symchych // Shutterstock
Sleep journals are a tool doctors can use to find out how much and how well a patient sleeps. In these journals, sleep patterns are recorded for a few weeks to identify things that may be interfering with a patient’s sleep. Sleep journals can be as simple as a sheet of paper with a template guiding patients on what information to fill out.
For patients who prefer not to use paper, phone apps are available to keep track of sleep and other vital information doctors might need. Because the information required for different forms of insomnia differs, it’s best to consult a doctor about what to include in the journal and the duration of tracking sleep.
Caffeine, nicotine, and alcohol are stimulants that can disrupt sleep. People with insomnia often experience fatigue due to their lack of sleep and use stimulants to help them feel less tired. However, stimulants have been linked to difficulty sleeping, resulting in a counter-productive attempt to treat insomnia.
Alcohol, which can also act as a sedative, prevents deeper stages of sleep necessary for adequate rest. Caffeine is also a common substance in coffee, soda, and other foods. Reducing caffeine intake by opting for decaffeinated products is a good practice. It’s also advisable to avoid consuming any of these substances at least six hours before bedtime.
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Caffeine, nicotine, and alcohol are stimulants that can disrupt sleep. People with insomnia often experience fatigue due to their lack of sleep and use stimulants to help them feel less tired. However, stimulants have been linked to difficulty sleeping, resulting in a counter-productive attempt to treat insomnia.
Alcohol, which can also act as a sedative, prevents deeper stages of sleep necessary for adequate rest. Caffeine is also a common substance in coffee, soda, and other foods. Reducing caffeine intake by opting for decaffeinated products is a good practice. It’s also advisable to avoid consuming any of these substances at least six hours before bedtime.
The environment you sleep in contributes to your sleep or lack of it. The light and sound in the environment are two factors that affect a person’s comfort as well as the amount and quality of sleep they get. To get better sleep, it’s a good idea to reduce exposure to light and create a dark space.
Reducing undesirable noises with a fan or another source of white noise makes it easier to fall asleep. The comfort of the bedroom is also a contributing factor to the amount of sleep an individual gets. Lowering the thermostat to keep the atmosphere cool and lower the body’s core temperature is also a great way to keep the environment comfortable for sleep.
Stock-Asso // Shutterstock
The environment you sleep in contributes to your sleep or lack of it. The light and sound in the environment are two factors that affect a person’s comfort as well as the amount and quality of sleep they get. To get better sleep, it’s a good idea to reduce exposure to light and create a dark space.
Reducing undesirable noises with a fan or another source of white noise makes it easier to fall asleep. The comfort of the bedroom is also a contributing factor to the amount of sleep an individual gets. Lowering the thermostat to keep the atmosphere cool and lower the body’s core temperature is also a great way to keep the environment comfortable for sleep.
While some can sleep with the light turned on, others prefer the lights turned off. Yet, no matter an individual’s preference, there are certain effects of light that affect sleep. White light, like sunlight, is made up of all the colors of the visible light spectrum, which affects alertness, hormone production, and sleep cycles.
Blue light, on the other hand, is a portion of the visible light spectrum. At night, it suppresses the secretion of melatonin, a hormone that makes us feel drowsy. Blue light deceives the brain into staying alert at night, making it difficult to sleep. A good practice is to stay off blue light-emitting devices—or use blue light-blocking filters on screens—at least an hour before your scheduled bedtime.
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While some can sleep with the light turned on, others prefer the lights turned off. Yet, no matter an individual’s preference, there are certain effects of light that affect sleep. White light, like sunlight, is made up of all the colors of the visible light spectrum, which affects alertness, hormone production, and sleep cycles.
Blue light, on the other hand, is a portion of the visible light spectrum. At night, it suppresses the secretion of melatonin, a hormone that makes us feel drowsy. Blue light deceives the brain into staying alert at night, making it difficult to sleep. A good practice is to stay off blue light-emitting devices—or use blue light-blocking filters on screens—at least an hour before your scheduled bedtime.
For a person to fall asleep, the body and mind need to be in a restful state. Sometimes the body is in the position to rest, but the mind keeps drifting. An excellent practice is repeating relaxation exercises before going to bed. This can be listening to music, reading a book, or any activity that helps you wind down. These activities help relaxation by lowering heart rate and blood pressure and improving general well-being.
Research shows these changes help us fall asleep. By relaxing, the body activates a natural process known as the “relaxation response,” which calms the mind, relaxes the body, and causes people to fall asleep naturally. The trick is to be open to relaxation exercises, stick to a sleep schedule, and repeat the exercise regularly.
Lasse Ansaharju // Shutterstock
For a person to fall asleep, the body and mind need to be in a restful state. Sometimes the body is in the position to rest, but the mind keeps drifting. An excellent practice is repeating relaxation exercises before going to bed. This can be listening to music, reading a book, or any activity that helps you wind down. These activities help relaxation by lowering heart rate and blood pressure and improving general well-being.
Research shows these changes help us fall asleep. By relaxing, the body activates a natural process known as the “relaxation response,” which calms the mind, relaxes the body, and causes people to fall asleep naturally. The trick is to be open to relaxation exercises, stick to a sleep schedule, and repeat the exercise regularly.
There are mindfulness techniques people claim can make you sleep at will. While there is no research to back these claims, visualization and breathing exercises can help people fall asleep. Body scans are a type of visualization exercise that involves paying systematic attention to various parts of the body. This technique is similar to one that is reportedly practiced in the U.S. Army. The aim is to shut down each part of your body, from the forehead to the feet.
Breathing exercises are also one of the most simple and basic ways to trigger the body’s natural relaxation response. This exercise not only helps to reduce tension and calm the body, but it also helps to strengthen the respiratory system.
Bangkok Click Studio // Shutterstock
There are mindfulness techniques people claim can make you sleep at will. While there is no research to back these claims, visualization and breathing exercises can help people fall asleep. Body scans are a type of visualization exercise that involves paying systematic attention to various parts of the body. This technique is similar to one that is reportedly practiced in the U.S. Army. The aim is to shut down each part of your body, from the forehead to the feet.
Breathing exercises are also one of the most simple and basic ways to trigger the body’s natural relaxation response. This exercise not only helps to reduce tension and calm the body, but it also helps to strengthen the respiratory system.
Cognitive behavioral therapy, or CBT-I, is a brief, organized, evidence-based treatment for insomnia symptoms. The treatment helps patients identify and replace attitudes and behaviors that trigger or worsen sleep problems with healthy sleep habits.
Unlike other treatment options such as sleeping pills, CBT-I helps patients address underlying causes of sleep issues. This makes cognitive behavioral therapy for insomnia a good option for treating long-term sleep problems. The American College of Physicians suggests that CBT-I is the first-line treatment for insomnia; this suggestion is given based on the treatment method’s effectiveness. When the CBT-I is utilized, 70% to 80% of persons with primary insomnia notice improvements, and the effect lasts.
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Cognitive behavioral therapy, or CBT-I, is a brief, organized, evidence-based treatment for insomnia symptoms. The treatment helps patients identify and replace attitudes and behaviors that trigger or worsen sleep problems with healthy sleep habits.
Unlike other treatment options such as sleeping pills, CBT-I helps patients address underlying causes of sleep issues. This makes cognitive behavioral therapy for insomnia a good option for treating long-term sleep problems. The American College of Physicians suggests that CBT-I is the first-line treatment for insomnia; this suggestion is given based on the treatment method’s effectiveness. When the CBT-I is utilized, 70% to 80% of persons with primary insomnia notice improvements, and the effect lasts.
After a stressful activity, naps are a simple remedy. However, taking a long snooze at the wrong moment might backfire. For some people, short naps won’t affect their nighttime sleep quality, but for people who experience insomnia, napping might do more harm than good.
This isn’t to argue that naps aren’t beneficial, but people need to understand how to get the most out of naps. The best way to take a nap is to keep them short, create a relaxing atmosphere, and avoid taking late afternoon naps that can interfere with nighttime sleep. Individual sleep schedules, age, medicine, and the desire for sleep all play a role in selecting the best time to nap.
Kosim Shukurov // Shutterstock
After a stressful activity, naps are a simple remedy. However, taking a long snooze at the wrong moment might backfire. For some people, short naps won’t affect their nighttime sleep quality, but for people who experience insomnia, napping might do more harm than good.
This isn’t to argue that naps aren’t beneficial, but people need to understand how to get the most out of naps. The best way to take a nap is to keep them short, create a relaxing atmosphere, and avoid taking late afternoon naps that can interfere with nighttime sleep. Individual sleep schedules, age, medicine, and the desire for sleep all play a role in selecting the best time to nap.
Some causes of insomnia don’t need to be treated with medication. However, if medical causes are not ruled out, consulting a doctor is the best line of action. It is not advisable to use any drug, including over-the-counter sleep aids, without notifying a medical provider.
Although some medications have been approved for long-term use, doctors do not advise taking prescription sleeping pills for more than a few weeks. Some drugs, especially sleep aids of the Z-drug class and benzodiazepines, can create dependence in just a few days. A sudden stop in taking these medications can also result in severe withdrawal symptoms. A safer route is to ensure a medical practitioner monitors the administration of sleep supplements such as melatonin or medication.
This story originally appeared on Sunday Citizen and was produced and distributed in partnership with Stacker Studio.
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Some causes of insomnia don’t need to be treated with medication. However, if medical causes are not ruled out, consulting a doctor is the best line of action. It is not advisable to use any drug, including over-the-counter sleep aids, without notifying a medical provider.
Although some medications have been approved for long-term use, doctors do not advise taking prescription sleeping pills for more than a few weeks. Some drugs, especially sleep aids of the Z-drug class and benzodiazepines, can create dependence in just a few days. A sudden stop in taking these medications can also result in severe withdrawal symptoms. A safer route is to ensure a medical practitioner monitors the administration of sleep supplements such as melatonin or medication.
This story originally appeared on Sunday Citizen and was produced and distributed in partnership with Stacker Studio.
Syncing your circadian rhythm to a natural light-dark cycle could improve your health and well-being. nambitomo/iStock via Getty Images Plus
Your hormones fluctuate rhythmically over the course of the day. The stress hormone cortisol typically peaks in the morning, while the sleep hormone melatonin typically peaks in the night. Pikovit44/iStock via Getty Images Plus
The best time of day to exercise might be the time when you feel you perform best. Anuruk Charoenamornrat/EyeEm via Getty Images
