He thought it might just be the stress of moving thousands of miles away from home to a new Army post. But as the days grew shorter, Albert Milliron found himself slipping into a sluggish depression that worsened as the hours of daylight dwindled. Originally, he was treated for depression, but eventually he realized that the short days and lack of daylight were part of his funk. People with SAD have lost the natural rhythm that signals the body to fall asleep and awake at the proper times, Dr. Rausch said. The body's light-sensing pineal gland responds to lessening light by secreting the hormone melatonin, which helps bring the body to rest.
Daylight signals the gland to shut off melatonin and allow the body to come awake.
But maintaining that cycle becomes more difficult for some people as the days grow shorter and light grows more scarce. Dr. Rausch likens it to the way the shorter days create hormonal changes in hibernating animals, causing them to sleep more, eat less, and slowing their metabolisms. Those with the disorder may experience similar sleep and eating changes. They also may have trouble concentrating, may become depressed and may even consider suicide. Researchers still don't know why some people are affected more than others, but they have found an effective natural treatment - returning daylight, particularly morning light, to the person's life.