Last week we talked about the importance of the number 24 in regard to sleep, because that (almost) is the amount of hours it takes to our planet Earth to rotate completely around itself, the rotation that alternates day to night. Precisely it is 23h56m4s.
This image leads us to another interesting (and sometimes controversial) topic: the circadian rhythm. This rhythm is a sort of inner biological clock living creatures have as an adaptation to life on this planet.
According to some researches conducted in the University of Harvard, the average length of human circadian rhythm is 24h15m. In patients with Non-24-hour sleep–wake disorder this duration can also be longer, hardly ever shorter.
An odd info: some argue that human beings come from Mars, since the rotation period of this planet is 24h37m23s. Our circadian rhythm is longer than the terrestrial rotation period, but shorter than the Martian, so our body would get adapted to terrestrial stimuli, but not entirely. In support of this hypothesis, there are also known to astronomers as Tom Van Flandern, former head of the US Naval Observatory.
Well, our circadian rhythm constantly adjusts, due to environmental stimuli, first of all light: dim lights and darkness calls for the production of melatonin, a hormone produced by the pineal gland that facilitates the sleep-wake cycle.
Research [1, 2] show that blue and green light help us stay awake and alert; for the same reason, exposition in the hours before sleep can interfere with the process of falling asleep. On the other hand, warm colors light (yellow, orange, red) is the right choice in the evenings.
This surely comes from atavistic environmental conditioning, the color of the sky and the vegetation to be the predominant during daylight hours, in contrast to the warm color of fire, the only possible overnight.
Therefore, to fall asleep more easily, it’s best to avoid the use of computer and other screens before going to bed, preferring a warm light to illuminate a book to accompany us in the arms of Morpheus.
The importance of the light is reflected by the research on blind people, whose rhythm is out of phase, with side effects such as insomnia and daytime sleepiness . In people with total blindness, the prevalence of altered sleep-wake cycle syndrome is 50 to 75%. In the general population, it has a prevalence of 1 in 2000: we are talking about then a rare disorder, although many people with this disorder do not communicate their doctor .
Talking about sleep disorders, we say goodbye until next week when we will continue to explore this topic.