You’ve heard the term "circadian rhythm," and you know that it has to do with the body's sleep cycle. But understanding just how this sleep rhythm works can help you get your body clock back on track when life throws it off schedule.
While we often refer to it as a single circadian rhythm, there are actually several circadian rhythms in the body, one of the essential ones being the sleep-wake cycle.
What Is a Circadian Rhythm?
Most bodily processes occur in rhythms or cycles. Those that take roughly 24 hours to complete are called circadian rhythms. The body’s circadian rhythms affect important functions like temperature, blood pressure, mental alertness, hormone levels and, of course, sleep.
Circadian rhythms are governed by a group of about 20,000 nerve cells that form a structure known as the suprachiasmatic nucleus (SCN) located in the hypothalamus in the middle of the brain. The SCN is responsive to daylight and uses information it receives from the eyes about incoming light to speed up, slow down or reset your body's clock by controlling levels of melatonin, a hormone needed for healthy sleep.
As it gets dark at night, the SCN tells the brain to produce more melatonin to induce sleepiness, and in the morning, when light increases, the SCN tells the brain to slow production of melatonin so you can wake up more easily.
Circadian Rhythm Sleep Disorders
All sounds pretty simple, right? The complications arise when work, school and social commitments interrupt sleep routines. One such example is jet lag, a common circadian rhythm disorder. It often occurs when an individual travels across several time zones and their sleep cycle has trouble adjusting. This type of disruption can cause insomnia, daytime drowsiness, irritability and difficulty concentrating, and it can take up to a week to adjust to the new schedule.
Another common disruption is the shift work disorder, which affects people who work night shifts or rotating shifts. They are awake when the body naturally wants to sleep, and they are sleeping (or attempting to sleep) during the day when the brain is programmed to be awake. Because of our natural disposition and the SCN's ability to signal melatonin production during daylight hours, those affected by the shift work disorder get less sleep than those who sleep at night, and their sleep is fragmented.
Adjusting Circadian Rhythms
At some point or another, most of us will experience some sort of unavoidable disruption to the circadian rhythm. But since we know sleep is essential to your immune function and general health, it’s important to keep in mind a few natural ways you can adjust your body's internal clock if it gets out of whack.
According to Sleep.org, factors like light exposure, exercise and mealtime schedule all affect the circadian rhythm and can be used to get your body back in sync. For example, if you need to get up at an earlier hour, light will be the most effective tool to help you feel less tired and get the sleep you need. Turn the lights down an hour before the desired bedtime to signal to the brain that it is time to sleep, and in the morning, turn on as many lights as possible to promote wakefulness.
You can also optimize your circadian rhythm by moving around mealtimes and workouts. For instance, if you want to be able to stay up later, try pushing dinner a little later. This moves the internal clock back and signals to the brain to go to sleep later. Physical activity in the evening rather than in the morning can have the same effect. However, it is a good idea to make these changes gradually and give the body time to adjust to your new schedule rather than making these changes overnight — literally.
Overall, the circadian rhythm is a vital part of the body's sleep cycle — which is why disrupting it can lead to a number of health problems. However, there are simple ways to reset the body's sleep habits even when there are issues like jet lag or shift work disorder to overcome. Try resetting your circadian rhythm for a better night's sleep and a better morning every day!