Real Possibilities
June 8-14, 2020
By Nan Selz
Executive Council, AARP Arkansas
Circadian Rhythm regulates much more than sleep
There’s a cluster of cells in the human brain that is meant to regulate most bodily functions.
and it is controlled by earth’s 24-hour cycle of light and dark. This daily cycle impacts physical, mental and behavioral changes, including sleeping at night and being awake during the day. When light hits the eye in the morning, the body begins to change its levels of melatonin and cortisol. Melatonin, which allows us to sleep, decreases; and cortisol, which prepares the body to become more active, increases. The process reverses itself in the evening when the sun goes down.
This process worked for primitive humans, but as science has brought electric light, television, and other technology into people’s lives, the sun is no longer our major source of light and its absence of dark. We still experience some light from the sun, but, even during the day, we are mostly in artificial (often fluorescent) light, and both day and night we are in front of screens emitting short-wavelength light, popularly known as blue light. This situation, called circadian dysregulation, can negatively affect not only our sleep patterns, it can also impact other bodily functions that are controlled by the same cluster of cells.
For example, there seems to be a connection between gastrointestinal difficulties and sleeplessness. Researchers are investigating whether circadian dysregulation impacts the trillions of bacteria in the digestive system known as the microbiome. If this proves to be true, it might be possible to take oral probiotics to rid shift workers and night owls of such negative symptoms as constipation and diarrhea.
Heart attacks occur two to three times more often in the morning than at night. Upon wakening, the body’s heart rate and blood pressure increase which is harmless in a healthy person. In a person with cardiovascular disease, however, this might trigger a heart attack. A study done in 2018 showed a 67% reduction in major cardiovascular events when patients took their heart medication at bedtime rather than in the morning.
Even our skin seems to react to whether it’s day or night. Research has shown that fibroblasts (skin cells that help wounds heal) act more efficiently to heal cuts faster during the day. Also, burns that happen during the day heal 60% faster than those incurred at night.
Lastly, light seems to impact our metabolism. Another study showed that people who were exposed to early morning light had lower BMIs (Body Mass Indexes) than those exposed to afternoon sun, and they were also more active throughout the day. Light seems to synchronize the functions in the brain that regulate appetite and metabolism.
Next month’s column will explore what we can do to combat circadian dysregulation and its effects. Information for this article was taken from the May 2020 issue of Prevention. To learn more about sleep and related issues, go to www.aarp.org and search for sleep.
