The circadian rhythm is a natural process that takes place throughout the day. It is not restricted to humans, and exists in most living things, even plants. For us, the circadian clock follows roughly a 24-hour cycle, responding primarily to light and darkness in our environment. It acts to regulate countless bodily functions.

One of the most important hormones in the context of circadian rhythms and sleep regulation is melatonin. Melatonin is a natural hormone that is produced by the pineal gland in the brain and then released into the bloodstream. Darkness prompts the pineal gland to start producing melatonin, while light causes that production to stop. Melatonin therefore helps regulate our circadian rhythm and synchronise our sleep-wake cycle with night and day. In doing so, it facilitates the transition to sleep and promotes consistent, quality rest.

What causes circadian rhythm disruptions?

Circadian rhythm disruptions can be the result of various factors:

Light: Light is the biggest disrupter to your internal body clock, which is why it’s harder to fall asleep during daylight hours and why you shouldn’t use electronic devices right before bed. Bright light can confuse your inner clock into thinking it is daytime, which can cause your body to secrete less melatonin, resulting in a more alert state at bedtime.

Time: Travelling across time zones can cause jet lag, which happens when your circadian rhythm has yet to adjust to the time difference of a new location. Shift work disorder can also disrupt our internal rhythm, as those who work night shifts and sleep during the day are going against the natural light-dark cycle, which can be a hard adjustment for the body to make.

Mood disorders: People with bipolar disorder or depression have an imbalance in their serotonin secretion. When your body cannot properly regulate its serotonin levels, it can trigger phase shifts in your circadian rhythm, affecting mood and appetite and causing irregular sleep patterns.

Long naps: Napping can completely throw off your sleep-wake rhythm. While short, 10- to 20-minute naps early in the afternoon can help you feel more refreshed, napping longer and later in the day makes you more likely to fall into a deep, REM sleep, making it difficult to fall asleep naturally later on.

Food: When you eat, your body releases insulin, the hormone that carries glucose from your blood into your muscles and other organs. Your kidneys need to work overtime to help remove the sugar from your blood, which can result in frequent urination during the night, disrupting healthy sleep.

How can you restore your circadian rhythm?

In order to effectively alter your circadian rhythm and sleep-wake cycle, we recommend the following:

Sleep schedule: Keeping a regular sleep schedule will help to reset your circadian rhythm. By going to sleep and waking up at the same time every day, your body will learn to adjust to the new rhythm. Even if you are unable to fall asleep at your desired time, make sure to set an alarm and wake up at the set time anyway. This will keep you on track.

• Start dimming lights about two hours before bedtime and resist scrolling through social media in bed. If you work a night shift or need to use screens in the evenings, you can wear glasses that block blue light or install a blue light filter app on your device.
• Circadian rhythms regulate when we feel hungry and how we digest food. Some studies have found that advancing or delaying meals can alter how your circadian rhythm regulates these processes, causing you to feel alert and tired at different times than those you’ve become accustomed to.
• Proper exercise can improve sleep quality and duration, while a healthy sleep-wake cycle ensures more strength and endurance when you work out. However, exercise is also stimulating if you work out too close to bedtime, so exercise at least one to two hours before.
• Caffeine has a half-life of five hours in a healthy adult, meaning it takes an average of five hours for the body to eliminate half the amount of caffeine consumed. For best results, consume a moderate amount of caffeine for the first few hours of being awake, but stop at least five to seven hours before bed.

Melatonin: In addition to the natural hormone produced in the pineal gland, melatonin is also available in supplement form. Melatonin supplements were not developed to treat insomnia; rather, they help to reschedule circadian rhythms.

These steps to improve sleep patterns can be an important part of supporting a healthy circadian rhythm, but other steps may be necessary depending on the situation. If you have persistent or severe sleep problems, daytime drowsiness and/or a problematic sleep schedule, it is important to talk with a doctor who can best diagnose the cause and offer the most appropriate treatment.