What Are Circadian Rhythms?
Circadian Rhythms are the patterns of changes in humans (as well and in plants, fungi, and animals) that occur within a 24-hour cycle to optimize functioning and health. These physiologic changes- in behaviors, mental functioning, digestion, hormonal variations, body temperature, immune functioning, and changes in energy levels- are influenced and regulated by a master biological clock in the brain that coordinates all these circadian rhythms.
This regulatory master molecular clock is called the suprachiasmatic nucleus (SCN) and is in the region of the brain called the hypothalamus. The SCN and hypothalamus receive direct input from the eyes and are highly sensitive to light, which helps the brain distinguish between night and day and keep the circadian rhythms coordinated and optimized. The Circadian system and SCN work to synchronize internal processes to the external world.
Circadian Rhythms and Sleep
One of the most well-known circadian rhythms is the sleep-wake cycle. During the day, when we are exposed to light, the body sends signals to keep us alert and awake. When night starts to fall and you are exposed to less light, the brain sends signals to produce melatonin which helps make you sleepy and keeps you asleep throughout the night.
There are things that can interrupt the sleep-wake cycle and interrupt sleep because they affect your master clock and sense of night and day. Jet lag, shift work, lack of time outside, and exposure to artificial light sources including electronics can affect the circadian rhythms and negatively impact the length, quality, and timing of sleep. These circadian rhythm sleep-wake disorders (CRSWD) can cause people to fall asleep early in the evening and wake very early in the morning, stay up late and sleep late into the day, or have interrupted and irregular sleep. There may also be underlying genetic causes that cause these disorders as well, though the genetic influences and mechanisms are just beginning to be understood.
How Do Circadian Rhythms Affect Mental Health & Wellness?
The circadian system and sleep-wake cycles can deeply impact mental and physical health and are connected to every system in the body. When these cycles are out of sync or there is a lack of sleep, all of the body’s physiological systems and overall health can suffer. Sleep and circadian rhythm disruption (SCRD) is connected to cognitive impairment and dementia, depression, and other psychiatric illnesses including bipolar disorder, disruptions in metabolism, obesity, sleep apnea, diabetes, and even the immune system responses necessary to prevent cancer.
Luckily, there are positive ways to support healthy circadian rhythms and healthy sleep-wake cycles that can positively impact your health and wellness in all of these ways.
Supporting Healthy Circadian Rhythms
Supporting healthy sleep and healthy circadian rhythms connect us to the natural world and our own integrated physiological systems, to support and optimize mental and physical health.
Spend time outside and in the sun – Exposure to natural light, especially early in the day, sends signals to the SCN which strongly influences the circadian rhythms.
Go to bed and wake up at roughly the same time each day – Being consistent with the time you go to sleep and wake up supports stable and consistent circadian rhythms.
Move your body – Among many other benefits of consistent exercise, getting daily exercise and being active during the day can help you fall asleep at night.
Limit caffeine, nicotine, and alcohol – Both caffeine and nicotine disrupt sleep, so avoiding excess caffeine (especially after noon) and nicotine can help you fall and stay asleep. Alcohol can make you sleepy but the effects do not last and may contribute to sleep disruption later in the night.
Limit electronics before and around your bed– Experts recommend turning off electronic devices like your phone, tablet, or computer 30-60 minutes before you want to go to sleep and keeping electronics out of the bedroom. The blue light emitted by electronic devices disrupts the production of melatonin and can cause disruption in falling and staying asleep.
Sources
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National Institute of General Medical Sciences. (2020, March 4). Circadian Rhythms. Retrieved August 12, 2021, https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms.aspx
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Sleep Foundation. (2020, September 25). Circadian Rhythm: What It Is, What Shapes It, and Why It’s Fundamental to Getting Quality Sleep. Retrieved August 12, 2021, https://www.sleepfoundation.org/circadian-rhythm
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