De-Mystifying Sleep Hygiene: The Science Behind Sound Sleep

Have you ever gone to your healthcare provider for help with sleep and been given a list of things to do to help you get to sleep? How did you like it? As a lifelong insomnia sufferer, I have experienced the joy of being handed the sleep-hygiene list. My physician’s intentions were good, but receiving a list of things I needed to do without knowing why I had to do them made me feel like a wayward child being given a list of rules to follow. I dutifully followed the rules I was given, but without knowing why I was doing it, I found it hard to remember what I needed to do and hard to keep it up.

Now that I’m a healthcare provider helping people understand and improve their health, I would like to do better by you. I’m not just going to help you know what you can do to improve your sleep but also why doing these things can help you. Finger-wag not included!

Photo by Brett Jordan on Unsplash

Understanding Sleep

To understand how sleep hygiene activities can benefit you, it helps to know how sleep works. There are two main processes at work to get you to sleep each night. One of these processes is called the circadian rhythm. The other process can be thought of as building up a sleep debt over the day. It is known as sleep homeostasis. Understanding these processes and how they work together makes it easier to see how sleep hygiene can help you.

Circadian Rhythm

Every cell in your body has a built-in clock-like mechanism that tracks a daily rhythm. Scientists believe that one master clock in a part of your brain called the suprachiasmatic nucleus (SCN) can regulate all the other clocks in each cell. This master clock gets its cue about what time of day it is from the light in the environment. Every day, it uses this information about how much light is in the environment and sets all the other cellular clocks in your body. This is how your cells know when to release hormones. The two most important hormones for regulating sleep are melatonin and cortisol.

Melatonin

Your pineal gland starts releasing melatonin 2 hours before you go to sleep. After 2 hours, there should be enough melatonin circulating that it is making you sleepy. Melatonin levels peak and level off while you are sleeping. When it’s time to wake up, the levels drop off sharply.

Cortisol

Many people know cortisol as the stress hormone, but it also regulates wakefulness. Production of cortisol starts to increase a few hours before waking and peaks 30–45 minutes after waking. This rapid increase has the effect of waking you up. If you have ever experienced waking up at the same time every day regardless of how much sleep you got, the morning cortisol spike is the likely culprit.

Melatonin and cortisol together regulate your sleep and wakefulness on a 24-hour schedule known as your circadian rhythm. But your circadian rhythm is not the only factor influencing your sleep.

Sleep Debt

Imagine that being awake is like spending on a credit card. Also, imagine that the more debt you rack up, the sleepier you feel. Over the day, your credit card balance increases until you max it out around when you usually go to bed. At that point, you fall asleep, and in doing so, you pay off the debt. If you don’t get enough sleep, you don’t fully pay off the debt, and you feel sleepy the next day.

Adenosine is the molecule that represents the debt in this analogy, and it is the substance that makes you sleepy when it builds up in your brain. It is a byproduct of metabolism that accumulates in your brain while awake. When you fall asleep, you clean your brain of it. The process starts over again the next day.

How Your Circadian Rhythm and Your Sleep Debt Work Together

In the morning, your cortisol levels rise, waking you up. If you have gotten a whole night’s sleep, then there won’t be accumulated adenosine to make you sleepy and so up you rise! As the day goes on, you start building up adenosine, but it isn’t enough to get you to sleep until later in the night when enough has gathered, and you also have melatonin, making you sleepy. Once you fall asleep, you immediately start eliminating adenosine. The reason you don’t wake up halfway through the night is that you have high melatonin levels throughout the night to keep you asleep. Come morning, the melatonin levels fall, and the cortisol levels rise, waking you up, and a new cycle begins.

What Could Go Wrong?

To have healthy sleep, you must keep your circadian rhythm in sync with your sleep debt cycle. Doing this can be tricky because your circadian rhythm is slightly longer than 24 hours. Daily light exposure at the right time resets the master clock in your brain, keeping your circadian rhythm to 24 hours. If you don’t get enough light exposure in the morning or too much light exposure at night, your circadian rhythm will drift and become misaligned with your sleep debt cycle. This will make it hard to fall asleep at the right time. You will end up falling asleep later in the night. Since most people have a particular time at which they need to wake up, it will be hard to get enough sleep. If you keep having inappropriate light exposure day after day, the problem will compound.

What to do?

• Get light exposure within an hour of waking up. Not through a window. This is among the most important things you can do to help your sleep. Getting light exposure in the morning will start your clock so that you get sleepy at the right time. Regular indoor light is not enough. You need to go outside. If going outside is not an option or it’s still dark when you wake up, you can use a lightbox. The key is to find a lightbox that can put out 10,000 lux worth of light. Lux is a measurement of light. If you use a lightbox, you will need to sit in front of it for at least 20 minutes, preferably 30 minutes.

• Avoid light exposure for 2 hours before bed. Even low levels of light can interfere with your melatonin production. Many people know that screens in the hours leading up to bedtime can interfere with sleep, but so can bright overhead lights. It’s unfortunate that these indoor lights aren’t bright enough to help you in the morning but are bright enough to harm your sleep at night.

• Eat on a regular schedule. Eating on a regular schedule has the effect of setting the cellular clocks in your liver and fat cells. While these cellular clocks do not have as powerful an influence as the master clock in your brain, they can still throw this system off if they are out of alignment. Eating on a regular schedule will help to keep them in alignment. Eating too close to bedtime will interfere with sleep because it causes your cells to act as though it is earlier in the day and ends up delaying what time they end up going into sleep mode.

• Exercise. Exercise is a powerful tool to help you sleep better. Research has shown that exercise in the morning has a time-setting effect on cellular clocks throughout your body. This effect shortens the length of the cell’s cycle. Most people’s cellular clocks run a little longer than 24 hours and have to be reset every day by environmental cues. After light exposure, exercise is one of the most robust cues you can give your body to shorten your cellular day. The key to using exercise to get better sleep is to try and do it in the morning; otherwise, it can set your clock to a later time and make it harder to get to sleep.

• Be careful with caffeine. Caffeine can stay in your system for 17 hours, and some people are very sensitive to caffeine. Caffeine blocks adenosine receptors in your brain, making it so you don’t feel sleepy despite your accumulated sleep debt. To use the credit card analogy, caffeine makes it as if the credit card company somehow forgot what your maximum limit is, so you blow past it instead of paying it off. Caffeine prevents you from feeling sleepy and from going to sleep and cleaning out adenosine. Since a lot of time can pass between when you take caffeine and when you go to sleep, it can be hard to relate your caffeine use to your lack of sleep. If you are having trouble sleeping, consider limiting your caffeine intake to one drink before noon.

• Be careful with naps. Naps can be helpful, but they can also harm your sleep. The key is to pay attention and be honest with yourself about which one of these the nap is doing for you. The way a nap can harm your sleep is by reducing your sleep debt. Going back to the credit card analogy, if you sleep hard enough in the middle of the day, you will pay off some of your sleep debt. When bedtime comes, you won’t have maxed out your credit card, so you may not feel tired enough to sleep.

A Word to People with Sleep Disorders

You may find it discouraging to hear about the ways you have control over your sleep when you have a sleep disorder that you don’t have control over. I encourage you to apply what information you can and keep the rest in your back pocket. While good sleep hygiene will not cure a sleep disorder, it can prevent a sleep disorder treatment from working. Seek treatment and apply these strategies as you are able.

Conclusion

If you think your sleep is essential, and you want to do what you can to make it the best it can be, sleep hygiene can help. Knowing how your body works enables you to take care of it better, which allows it to take care of you better. You don’t have to do the things you read about here all at once to start reaping the benefits. You can do them one at a time. If you aren’t perfect, remember to be kind and forgive yourself. I don’t know of anyone who gets sleep hygiene perfect, but doing the best you can goes a long way to improving your health.

Originally published in Medium. Click here to go to original article.