The Body Clock Reset:
How to Optimize Your Circadian Rhythm and Get Better Sleep Naturally

BY SATCHIN PANDA, Ph.D.

We want to get the most out of our daytime activities and nighttime rest. The goal is twofold: First, we want to adjust our activities to the optimal times of the day that are most in sync with our clocks. We want to eat when we metabolize foods the most efficiently, we want to be active when our brain and body are functioning at their peak levels, and we want to get the right amount of sleep so that we can do it all again tomorrow. Second, we can fix disruptions, retrain and reset our internal body clock to improve our health. 

It would be a totally rational guess to assume that the first thing we need to fix is our eating pattern. But in reality, circadian clocks will readjust best when addressing our evening activities, namely limiting our access to light and enhancing sleep. The reason is because sleep is not a passive experience: The human body begins to get ready for the day the night before. Just like we start off the New Year with a celebration on December 31, sleep is the beginning of our biological day, not the end.

Every day, our body battles with lots of stressors that create cellular damage. At night, we aren’t just making necessary repairs to the body; the brain is also busy consolidating memories and sending out instructions to prepare us for the next round of activity. The changes that happen at night are absolutely critical to how we feel the next day. That’s why when we are in good health and have the right amount of sleep, we wake up feeling refreshed. Hence, if you want to improve your productivity and health, you need to adjust your circadian cycle based on your day-to-day activities.

The Stages of Sleep

The very first thing to do if you want to know how to reset your circadian rhythm is to get familiarized with the different sleep stages. Great sleep is created when there are cycles of quiet sleep and active sleep. The quiet sleep takes place in three stages that occur in a specific sequence: N1 (drowsiness), N2 (light sleep), and N3 (deep sleep). Unless something disturbs the process, you will proceed smoothly from one stage to the next, and as you do, your body and brain perform different functions depending on your clocks. First, in making the transition from wakefulness into light sleep, you spend only a few minutes in stage N1 sleep, but your body and brain change rapidly: Your body temperature begins to drop, your muscles relax, and your eyes move slowly from side to side. During stage N1 sleep, you begin to lose awareness of your surroundings, but you can be easily jarred awake.

The N2 stage, or light sleep, is really the first phase of true sleep. During this sleep stage, your eyes are still and your heart rate and breathing slow down. Brief bursts of brain activity called sleep spindles occur, as brain waves speed up for roughly half a second or longer. Some researchers believe that sleep spindles play a role in consolidating memories.

Stage N3, or deep sleep, occurs as the brain becomes less responsive to external stimuli, making it difficult to wake up. Your breathing becomes more regular. Your blood pressure falls, and your pulse rate slows 20 to 30 percent below the waking rate. Your blood flow is directed less toward your brain, which cools measurably. Right before this stage ends, the muscles that allow you to be upright against gravity become paralyzed, which prevents you from acting out your dreams. However, there are some real sleep disorders—like sleepwalking and sleep eating—in which this change doesn’t occur. A loss of sleep during this stage may play a role in reducing daytime creativity, mood, and fine motor skills. If you always experience this on a regular basis, then you should start finding effective ways on how to reset the body clock.

These three stages of quiet sleep alternate with periods of active sleep, which is referred to as REM sleep, which stands for rapid eye movement sleep. During this time, your body is still but your mind is racing. Your eyes dart back and forth behind closed lids. Your blood pressure increases, and your heart rate and breathing speed up to daytime levels.

Dreaming also occurs during REM sleep. We typically have between three to five cycles of REM sleep per night, occurring every 90 to 120 minutes. Each time you move from quiet sleep to REM sleep, you complete a sleep cycle. For optimal health, you need a balance of the different types of sleep throughout the night. Adults need at least 7 consecutive hours of sleep each night. So, if you short yourself by 90 minutes or more, you lose the equivalent of one entire sleep cycle. When you sacrifice a cycle of sleep or more of REM sleep, your circadian rhythm may be disrupted.

Within that 7-hour period, there is a critical 4-hour window. You may notice that between the hours of 10:00 p.m. and 2:00 a.m., or in the first 4 hours after falling asleep, you get some of your best sleep. This is because these first few hours go toward paying back your sleep debt. They neutralize the urge to sleep or the tiredness you feel before going to bed. This is why it may be harder to go back to sleep if you wake up after that 4-hour period: You no longer have the sleep debt that was making you tired in the first place. The next 3-plus hours of sleep go toward nurturing your brain and body, giving them the additional time they need for repair and rejuvenation.

Shift workers who have to sleep during the daytime also experience circadian rhythm disruption. Most of these individuals look for ways on how to reset the body clock. However, in most cases, they find it hard to adjust their internal body clock due to some environmental and physiological factors. Since this is not the typical time nor the optimal lighting for the circadian clock to send its signal for sleep, shift workers aren’t able to get the maximum number of sleep cycles during the daytime, even if they try to sleep for 7 hours. This is why when you nap in the daytime you can rarely sleep for more than 2 to 3 hours: Your circadian code won’t allow it.

Understanding Sleep Debt

Carefully understanding what sleep debt is could also be helpful on your journey to finding effective ways on how to reset your sleep cycle. As soon as we wake up, our suprachiasmatic nucleus (SCN) clock begins keeping track of wakeful time. For every hour we stay awake, we later have to sleep 20 to 30 minutes.

Every night adults should give themselves 8 consecutive hours of sleep opportunity, and children should have 10 hours of sleep opportunity. That includes getting into bed, settling down, and then falling asleep. Children should be sleeping for at least 9 hours a night; adults should sleep for no fewer than 7 hours.

Sleep debt is the difference between the amount of sleep you should be getting and the amount you actually get. So, if you slept for 6½ hours last night, you’re beginning your day with 30 minutes of sleep debt. When you go to sleep the following night, you first repay this debt from the previous night. That means even if you sleep 7 hours the second night, it only counts as sleeping for 6.5 again. That’s one of the reasons why we often sleep late on weekends: It’s the body’s way of repaying your entire debt.

Napping Counts toward Repaying Your Sleep Debt

A short nap during the day is one way to repay your sleep debt. For example, if you had a sleep debt from the week of 2 hours and you take a Saturday afternoon nap, it’s possible to repay that debt in one nap.

The only times when napping really works against you are when you are jet-lagged, if you are a true shift worker and you want to sleep at night, or if you are really trying to move your bedtime to earlier in the evening. In these instances, it’s better to build up your propensity to sleep at night, and then reset your internal body clock the next morning.

The U Curve of Sleep and Longevity

There are real benefits to achieving the prescribed number of hours of sleep. From tracking a million individuals, researchers have identified a sleep pattern, known as the U curve of sleep and longevity. People who consistently sleep too little are more likely to die early than those who get the full 7 hours of sleep each night. Similarly, people who sleep as much as 10 to 11 hours are also likely to live shorter lives.

Let’s Get to Sleep!

How to reset your sleep schedule? The basic lesson for improving sleep or is to increase the drive to sleep in the first place and avoid the factors that suppress or disrupt sleep. In the daytime, the drive to sleep is affected by many factors:

+ Length of time one has been awake: Sleep drive increases with every hour we are awake. If you want to go to bed early, you should wake up early as well.

+ Exercise or physical activity: Physical activity, particularly outdoor activity under the sun or under diffuse daylight, increases the drive to sleep.

+ Timing of caffeine intake: Caffeine reduces our sleep drive and keeps us awake. Reducing caffeine after midday is a good general rule of thumb.

Food, Timing, and Sleep

Food is another significant factor to look into if you want to know how to reset your circadian rhythm naturally. Eating late at night is not only bad for metabolism, it also affects sleep. This habit interferes both with falling asleep and maintaining deep sleep. In order to fall asleep, our core body temperature must cool down by almost 1°F. But when we eat, our core body temperature actually goes up as blood rushes to the gut (the core) to help digest and absorb nutrients. So, eating late at night prevents us from getting into a deep sleep. To have a good night’s sleep, we should have our last meal at least 2 to 4 hours before going to bed to ensure that the body is able to cool down.

Sleep Is Inhibited by Light at Night

Another factor that could affect your the circadian cycle is the light that you are exposed to before going to bed. The easiest sleep fix is to maintain a dark sleeping environment. Everyone knows it is hard to fall asleep under bright light. Your circadian clock prevents this. The blue light sensors pick up the bright light to suppress sleep and promote wakefulness. However, other colors in the light spectrum, specifically orange and red, are less effective at suppressing sleep.

Pay attention to the type of light that you are exposed to in the evening. We cannot go back to the dark ages or turn off all lights after sunset, but managing our exposure to light can have a huge impact on improving sleep and maintaining health.

Hacking Your Way to a Better Night’s Sleep

A good night’s sleep ensures better performance the next day. It puts you in better alignment with your circadian code by increasing growth hormone production while you rest, rejuvenating your brain and body. It increases your cortisol production in the morning, which helps with alertness, and balances your hunger and satiety hormones for stronger, more efficient metabolism. Best of all, it synchronizes all of your internal clocks so that your whole body is working at peak performance.

If you are consistently not getting a good night’s sleep, or if you are waking up at night, try the following techniques on how to reset the body clock.

Turn Down the Temperature

The body has to cool down during nighttime to sleep. It’s a good idea to reduce the temperature in your bedroom to 70°F or lower so that your skin feels cooler. When this happens, blood flows toward your skin to keep your skin warm. Since the blood is flowing away from the core of the body, the core body temperature can fall and you will fall asleep much easier.

Behavioral Techniques for Better Sleep

1. One helpful tip on how to reset your sleep schedule is by simply not looking at your watch/clock/phone when you cannot get to sleep or if you wake up in the middle of the night. Why? Because the light from these devices will trigger your melanopsin. It really doesn’t matter what time it is when you wake up in the middle of the night, and there’s no benefit to starting to worry about not getting enough sleep. If you need an alarm to wake up at a certain time, that’s fine: Set it and cover it so that even those lights don’t disturb your sleep.

2. Don’t create stress around bedtime or worry that you will wake up late the next day. That’s what alarm clocks are for. Relying on alarm clocks is not ideal, but as you are working on improving your circadian code, there is a place for them in your life. Instead of worrying that you won’t wake up on time, try deep belly breathing to relax your body and mind.

3. Don’t create stress about your last night’s sleep and worry that you’ll have the same bad experience again. You are in control of your sleep. By following the “how to reset your circadian rhythm” recommendations we’ve laid out in this article, it’s quite likely that your sleep will improve, bit by bit, every night.

4. Don’t create stress about the number of hours you’re currently sleeping. If you are feeling fine and restored the next day, you may not need as much sleep as others. But if you don’t feel rested and refreshed in the morning, or if you feel sleepy during the late afternoon, try some of the tips in my book The Circadian Code.

5.  Don’t use the bedroom for anything other than sleep. It’s not a study or a living room or a home theater.

The Best Ways to Wake Up

Is there any room for improvement to optimize waking up?

+ The best way to wake up refreshed is to have enough sleep by going to bed early.

+ Get some bright light immediately after completing one cycle of sleep. Open your curtains or turn on your overhead light. Get as close to the window as possible.

+ Take a quick, 5- to 15-minute morning walk. Check your plants, check the bird feeder, play with your dog in the backyard, brush off your car. Do anything that will take you out of the house and into bright daylight.

+ Another important step on how to reset your circadian rhythm naturally is being consistent. Try to be consistent and wake up at the same time every day. If you are waking up 2 hours later on the weekends, it is a fair sign that you are not getting restorative sleep during the week.

Excerpted from the book The Circadian Code: Lose Weight, Supercharge Your Energy, and Transform Your Health from Morning to Midnight. Copyright © 2018 by Satchin Panda, Ph.D. Published by Rodale Books, an imprint of Penguin Random House LLC.

About The Author

Satchin Panda, Ph.D., is a leading expert in the field of circadian rhythm research. He is a professor at the Salk Institute and a founding executive member of the Center for Circadian Biology at the University of California, San Diego. Dr. Panda is a Pew Scholar and a recipient of the Julie Martin Mid-Career Award in Aging Research. Learn more at circadiancode.com