SAD is a form of depression or bipolar disorder where the affected person's moods cycle with the seasons of the year. It is common for people to be depressed in the winter when they are getting less natural sunlight.

Seasonal Affective Disorder (SAD) is a problem which, if I remember correctly, the experts claim is caused by reduced sunlight caused by the shorter days starting in fall, winter, and possibly extending into spring. It supposedly affects some people, probably a small percentage of the population, but is often described in the news as a simple fact, implying it happens to everyone. I have a hard time believing this disorder exists, and that it can be treated by looking at a bright light for about 20 minutes or whatever, daily. Sitting with my eyes 24 inches(=60 cm) from my CRT computer monitor is a fair amount of light, but I don't feel any relief from depression. Perhaps it's insufficient light. This is about the time of year when you will soon start to see SAD mentioned in the news. I feel depressed at this time of year. Don't worry, I 'm not suicidal, but I miss the warm weather of summer, and yes, the 9 hours of daylight in January is sort of depressing compared with the 15 hours of daylight on July 1. But I'm not ordinarily a sun-worshipper in the summer, anyway, because I fear getting a sunburn or skin cancer. I believe people may get depressed starting with autumn, but I believe there may be so much more causing it than merely reduced hours of daylight. Think of what else we lose starting with the cool fall weather. I'm a single unattached man and when I'm out in the public, I see a lot less skin, now that it's mid-October in southern Ontario, Canada. I think skin is a pleasing, soothing, sight. I'm not a beach person in the summer, because I'm shy and believe beaches are for parties and families, but I think there's probably a lot of happy people at beaches, in part, because people can see so much skin. As I recall, the people interviewed at the fall start of SAD look like shy, lonely, people, and I think each interview involves only one person affected by SAD. Are happily married people or other loving couples affected by SAD? There are expressions of summer love and summer romance. Maybe some people end a summer romance or give up trying to start one, by the start of fall. That would be depressing. I think being happily in love would have a great effect on reducing or minimizing SAD. If people are in love and having sex, or having sex without love, at least these people are seeing skin. The shy, lonely, people may not be. Men are more likely to view adult magazines or movies, or visit strip clubs, compared with women, which brings to mind, are as many women as men affected by SAD? The quick definition of SAD being caused by less exposure to sunlight, implies to me, less direct sunlight. This implies to me that living in a cloudy city, such as Honolulu, Hawaii, where about 75% of the year is cloudy days, is supposed to be depressing most of the year, compared with a sunny city such as Tucson, Arizona, where probably about 90% of the year is sunny days. I don't believe it. Honolulu is nicknamed paradise and I believe if I ever visit there, I would be delighted, even in January if every day was cloudy. The warm weather and comfortable humidity would be an incredible improvement. I have no desire to sit and look at a panel of light to treat SAD.

Sunlight gives the body Vitamin D and facilitates the production of melatonin (which tells us when to go to bed and when to wake up) through UVB rays (note that you CANNOT get these from just ANY light fixture, despite what the poster above might think about his/her computer monitor. That sort of light just confuses your body, actually. There's even a term for it: over-illumination). Anyway, being as though sunlight is the source of these things, we, naturally, produce less of them when the sun is farther away from the surface of the earth. People who don't have a "stockpile" of these things, so to speak, or who produce them slower than others, are more likely to be affected with SAD. You're basically like a car that is running really low near empty on gas - you still go, but you sputter and stall more than usual. There are also similar reasoning behind it, like it just feels better to know that you have "more time in the day" to get things done, etc... But sunlight, to be succinct, gives us certain nutrients that we feel "blah" without during the winter months. AKA, Seasonal Affective Disorder.

For those people who do not have the option of visiting sunnier places (like those of us in the UK) during the winter months, I can attest that a light box CAN help people suffering from SAD - it certainly helps me.

My office is west facing so by the time the sun gets around to my side of the house during the winter months it is almost sunset.

I use a light box to simulate bright, natural daylight and clinical studies prove that this can help around 65% of people suffering from SAD. Light boxes used for treating SAD are not just lights. They are very bright, almost painfully bright. You sit in front of them for a brief period at a time an hour or more before local wintertime dawn, simulating summertime dawn. This resynchronises ones internal "clock" and other brain systems.