The body has several internal biological clocks running behind-the-scenes to maintain processes and functions. The 24-hour circadian rhythm—derived from the Latin circa (around) and diem (a day)—regulates the sleep-wake cycle.
Below, we dive into the science-backed specifics of how your body's internal clock works and why regulating it is important for your long-term sleep health.
How circadian rhythms work
There are countless examples of biological clocks in humans and other animals. In addition to the circadian sleep-wake cycle, you have the menstrual cycle for women, hibernation cycle for animals that remain within their shelter for the winter, nocturnal cycle for animals that only come out at night, budding cycle for flowers that open and close at certain times, etc.
For humans, circadian rhythms are controlled by two factors:
- Proteins produced in the digestive system based on the timing of meals
- Hormones produced by the endocrine system based on energy expenditure
Together, proteins and hormones control your circadian pacemaker, which shoots out signals from the hypothalamus area of the brain—the suprachiasmatic nucleus (or SCN), to be exact. (1)
How circadian rhythms affects sleep
SCN is sensitive to social activity, temperature, and exercise, but nothing is as important as light. This is why circadian rhythms are so closely linked to day and night.
They’re more approximate than exact when it comes to the length of time, since not every person is oscillating on a perfect 24 hours.
Take night owls, for example. They’re what’s called delayed sleep phase circadian rhythm types who run on a longer internal clock. It’s easy for them to get a second wind at night, during which time they’re surprisingly awake and alert. The result, however, is that it’s increasingly challenging to wake up come morning. These are the always-hit-snooze-kind of sleepers, who may have a tendency to sleep through their alarms. Although they’ll get sufficient hours of sleep, their schedule will be delayed.
On the other hand, you have the morning larks, or advanced circadian rhythm types. For them, it’s hard to stay awake in the evening, but they’re the early birds who jump out of bed ready to start the day.
Most people find themselves somewhere in-between without a strong biological pull in either direction.
Common circadian rhythm sleep disorders
- Jet lag
Officially known as "Rapid Time Zone Change Syndrome," jet lag messes with your sleep times and wake times as you cross into new time zones, especially when traveling east.
- Shift Work Disorder
Those with inconsistent work schedules have been found to get upwards of four fewer hours of sleep than the average person.
- Delayed Sleep Phase Disorder (DSPS)
Night owls who fall asleep late but have a hard time getting up in the morning (common with teens and young adults).
- Advanced Sleep Phase Disorder
Early birds whose body clock causes them to fall asleep and wake up on the early side (common with older adults).
- Irregular Sleep-Wake Rhythm Disorder
When someone's sleep patterns are flipped upside down due to one-too-many naps over a 24-hour period.
3 ways to regulate your sleep-wake cycle
The first step in regulating your circadian rhythm is to understand it. What rhythm does your body thrive best on? This way, you’ll be able to notice when that’s thrown off due to factors such as Daylight Savings Time, jet lag, shift work, stress, changes in routine, medications, menopause, pregnancy, etc.
- Get outside
Natural light exposure is the most potent factor in regulating our 24-hour cycles. If you can, sneak outside for 15 minutes (morning is the best time of day) in order to reinforce this circadian cue. This trick is particularly helpful when traveling and suffering from jet lag of just a few hours difference (not 8-12 hours). Once you get to your destination, resist the urge to take a catnap in your hotel room. Instead, get outside and chase the sunshine!
- Go to bed and get up around the same time every day (even on the weekends)
If the schedule of when we are awake and asleep varies considerably, it can cause confusion for the body and throw off the physiological processes that thrive off of the routine of a 24-hour day, resulting in feelings of perpetual jet lag that prevents healthy sleep.
- Supplement with melatonin
Melatonin is a hormone our bodies naturally produce to regulate the sleep-wake cycle. Quantities increase as the sun goes down and decrease during daytime hours. Some choose to supplement their natural melatonin levels as a way to effectively adjust and regulate their internal clocks. Proper’s Sleep + Restore supplement was specifically formulated for this reason and designed for anyone struggling with poor sleep health (falling asleep, staying asleep, and/or feeling rested upon waking) in addition to a disrupted sleep schedule due to jet lag across time zones, after a night shift, etc. It’s powered by melatonin, which has been shown to support the initiation of sleep, as well as MicroActive® (MA) extended-release melatonin, which has been shown in dissolution studies to provide support throughout the night rather than just during the first hour.
Note: If you are pregnant or breastfeeding, please seek medical advice from your healthcare provider prior to taking any dietary supplements/sleep medicine. It’s also best to consult with your doctor to ensure whichever supplement you choose won’t interact with other medications you’re taking for conditions such as high blood pressure, antidepressants, etc. About Herbs and Drugs.com are two great resources for this.