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The mystery of the rhythms of sleep

Betty Firth
Posted 2/21/24

“Sleeping is the most mysterious thing we do,” according to Bill Bryson, author of “The Body; A Guide for Occupants.” That was a new thought for me. I had thought of sleep as …

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The mystery of the rhythms of sleep


“Sleeping is the most mysterious thing we do,” according to Bill Bryson, author of “The Body; A Guide for Occupants.” That was a new thought for me. I had thought of sleep as being necessary, inviting, evasive, and sometimes annoying, at least the need for it, when I wanted to sleep less and get other things done, but I had never thought of it as mysterious. What I did find puzzling, some might say “mysterious,” is why so many people have difficulty getting a good night’s sleep. In 2008, I broke my ankle, and a circle of friends I called my Ankle Angels helped me out with various tasks. I learned that every single one of them consistently had sleep issues to the point that it interfered with their daily lives. What are the odds that 100-percent of this circle of helpers all had problems sleeping?
Bryson describes sleep as a tune-up for the body, tied to many biological processes: “restoring hormonal balance, emptying the brain of accumulated neurotoxins, resetting the immune system, and consolidating memories.” He theorizes that dreams may be the result of the nightly housecleaning, tossing together random memories, anxieties, fantasies, and suppressed emotions, which, if remembered at all, are often a jumble of nonsensical fragments.
I learned that on average we are sleeping less than we did 50 years ago, from eight and one-half hours to under seven, which many experts feel is not enough. Ten to twenty percent of adults in the world suffer from insomnia, which has been linked to diabetes, cancer, hypertension, stroke, heart disease, and depression, and is possibly a contributing factor in Alzheimer’s.
If it wasn’t already obvious, that makes it evident that getting a good night’s sleep is a pretty good idea. Every part of our body needs sleep and will not function as well if deprived; if deprived long enough, we will die, but specifically why that happens does remain a mystery. Yet people persist in ignoring well-publicized advice for getting good sleep: sleep in a completely dark room; leave the phones and the TVs out of the bedroom; and avoid active use of other screens, especially smartphones and computers, one or more hours before bedtime. The blue light reduces melatonin, which helps the brain track the day length and prepare the body for sleep. With our access to inexpensive electricity, we are very used to creating our own schedule of light and dark, oblivious to the negative effects that may be having on our minds and bodies.
In 1999, Russell Foster, a researcher at Imperial College in London, proved that our eyes contain a third photoreceptor cell type in addition to rods and cones. These photosensitive retinal ganglion cells only detect brightness and have nothing to do with vision. They pass this information on to bundles of neurons within the hypothalamus, known as suprachiasmatic nuclei, which control our circadian rhythms. His discovery was scoffed at for a while, because the ophthalmological world was stunned to think it has missed this significant information for so long. Foster is now professor of circadian neuroscience at Oxford University.
It is now known that we have circadian rhythms, or body clocks, in nearly every tissue and organ, not just in our brain. What exactly are they? They are the physical, mental, and behavioral changes an organism experiences over a 24-hour cycle. They dictate when hormones are released and when organs are busiest or most relaxed. They affect sleep patterns, body temperature, appetite, and digestion. Light and dark are the primary influence on circadian rhythms, but they are also affected by food, stress, physical activity, temperature, and social environment.
In the short term, disturbances to the daily rhythms of the body can cause drowsiness, poor coordination and difficulty with focus and learning, which many notice when jet lagged from crossing multiple time zones; the body can’t keep up. Many people react badly when an hour shifts for Daylight Savings, an artificial manipulation I personally feel is completely unnecessary. As mentioned above regarding insomnia, long term, continually shifting circadian rhythms are thought to increase the risk for serious diseases. While we blithely stay up until midnight to watch our favorite show or short ourselves sleep to get an early start to the day, we may be doing more damage than suffering a bit of sleepiness. People who work on night shifts or changing shifts, are at a higher risk for negative effects, and some conditions such as autism, Alzheimer’s, and Parkinson’s can disrupt rhythms.
People of different ages have different rhythms and different needs for sleep. Recently, there has been more awareness that teenagers have a circadian rhythm that can be two hours different from other people, which is why it is deleterious to their focus, attendance, and test results to have the school day starting very early. Schools with later starting times have also seen fewer car accidents and less depression and self-harm. The kids are not just being lazy.
A normal night has a series of cycles repeated four or five times a night. Each one lasts about 90 minutes and involves four main phases. In the first two phases, sleep is so light, you may think you’re awake: relinquishing consciousness (5-15 minutes) and light slumber (20 minutes). Then comes deeper sleep, lasting about an hour, when it’s harder to wake up a sleeper. Lastly, rapid eye movement (REM) phase when the brain is as lively as when awake. The sleeper is mostly paralyzed except for the heart, lung, and eyes, which keeps us from hurting ourselves or others when thrashing about or escaping monsters. Often people doing sleep studies for sleep apnea think they slept through the night or awakened once or twice, only to find they woke up dozens of times when they quit breathing. The preponderance of people with this serious condition is another alarming phenomenon indicating we are out of sync with Mother Nature and our own natures.
Western scientists and doctors weren’t the first to discover the rhythms of the body. Traditional Chinese Medicine is based on using medical treatment that is in harmony with the natural laws of the body. TCM has used a circadian rhythm of diagnosing and treating illness for thousands of years based on the 24-hour and seasonal flow of chi (life energy) through the twelve major meridians of the body. More on that next month.