In my ongoing pursuit of a good night’s sleep, I have been led to check into circadian rhythms. One might think that going to sleep in darkness and waking when the light comes up is “natural.” I suppose it is, but also very complicated.
Circadian rhythms are produced endogenously. They are built into the body, per se, and not the result of an external stimulus, such as the sun coming up or alternately going down. They were discovered by a French person who noted that a certain flower opened and closed its leaves when left completely in the dark in the course of a day cycle.
Or in other words, if a person was locked in a room with 24 hour light, he or she would nonetheless, with no cue from the sun, begin to feel drowsy and sleepy at one time and wakeful at another.
The clock is said to go in a 24 hour cycle, though this is not accurate since the idea of a 24 hour day is but a human convention. More accurately one might say that the rhythm goes though a complete cycle from one sunset to the next, even though the rhythm is not stimulated by the sun setting.
This rhythm is found in all sorts of plants and animals and evolutionarily speaking must have arisen from some relation to the movements of the sun.
Why I have to wonder—did it become necessary for the body to internalize the mechanism of the cycle. What ever the reason, it did.
Whatever the reason when a certain time of day is reached, say night, the biological clock sets in motion the release of the hormone melatonin which is said to induce sleep. But this clock does respond to some degree to external stimuli; when for example the seasons change the clock resets itself to synchronize with the changes in light and dark.
Some believe that some sleep disorders may be related to screw ups in the circadian rhythms. Jet-lag is the prime example; people traveling from the US to China may take a week to readjust the clock. They feel awake when it is dark and sleepy when it is light. Some believe that work at the genetic and cellular level may help with people whose clocks seem permanently screwed up.
Another factor leading to screw ups may be the electrical light bulb. Most likely in the pre historic past, when there were no light bulbs, your average cave person went to sleep when the sun went down and arouse when the sun came up. This would make sense—a perfect synchronicity between sun and the biological clock.
Others argue that the winter blues may in part result from the abruptness of the time change produced by the artifice of Day Light Savings Time. These people are pretty serious and believe that a good deal of mental distress, even illness may be produced by Day Light Savings Time.
Personally, I dread each year the arrival of Day Light Savings Time. Perhaps my sense of fatigue is produced by the government of the United States that instituted Day Light Savings Time so people would have more time to shop. Perhaps my mental health is being destroyed by big business.