Why Sunlight Is So Good For You
Even Hippocrates believed that the changing seasons had something to do with health—and that the key was how much available daylight there was during different times of the year.
Many centuries later, it’s clear he was onto something. As people spend more time indoors staring at computer and television screens, scientists are starting to appreciate how exposure to sunlight affects various body systems.
The most interesting support for our dependence on daylight emerged with a condition called Seasonal Affective Disorder, or SAD. The term was coined by Dr. Normal Rosenthal at Georgetown University to describe the so-called winter blues: the lethargy and feelings of sadness and hopelessness that come when the weather forces people to spend more time indoors and the season provides little opportunity for exposure to natural light. Some people have speculated that our modern lifestyle, which keeps people indoors under artificial light for so many hours, may be encouraging a form of SAD year-round.
Rosenthal found that while not everyone is as strongly affected by a lack of sunlight, for the people who are, light boxes that blast a few minutes of bright light in the frequency of natural sunlight each morning can help to elevate mood and re-energize them to face the day.
Studies of shift workers also support the possible role that exposure to sunlight has on mood. Messing up the normal light and dark cycles by sleeping during the day and being awake at night, under artificial light, can disrupt the body’s metabolism. That can have domino effects on nearly everything: how we break down energy from food, how strong our immune systems are and the vast array of brain chemicals and other substances that contribute to mood, weight, energy and more. People who consistently work night shifts, for example, tend to be heavier than people who don’t.