Alan Bellows has posted an article on how unnatural light, such as light from light bulb may create unnatural behavior for humans. It affects our hormone and varies the rhythms of the day and night time which the brain perceives:

… Once humans began to use artificial light to vary the length of the day, the average night’s sleep decreased from about nine hours to about seven, and the amount of sleep began to vary considerably from one night to the next. This irregularity prevents one’s circadian rhythm from settling into a pattern, and creates a state of perpetual semi-jet-lag. Our bodies’ rhythms attempt to appropriately adjust our alertness, blood pressure, and such for particular times of day; but we often do things contrary to this cycle, and therein lies the problem.

A growing number of doctors believe that betraying our internal clocks is the source of a host of health problems. Once night falls, the body stays awake by activating the stress response, which in turn weakens the immune system. This is evidenced by the fact that individuals working graveyard shifts are more susceptible to stress, constipation, stomach ulcers, depression, and heart disease…

It is an interesting article on how light affects the circadian rhythms. Read the full article if you are interested.

Shortness of Dark – [Damn Interesting]

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