Many people think seasonal depression is that feeling you get right after the holidays, when all that's left to do is cram the decorations back into their respective boxes and return the bathrobe and bag of socks.

Millions of Americans know the truth. Seasonal Affect Disorder, or SAD for short, can completely disrupt your life. It leaves you feeling irritable, anxious, tired and often lost, because you don't know why you suddenly feel this way, when the rest of the year you function as a perfectly normal human being.

SAD is a common disorder felt during the fall and winter months, when the days are shorter and sunlight is not as readily available. Sunlight actually plays a key role in your brain chemistry. Did you know that? Yep, the sun's been getting a bad rap from the anti-aging industry as of late, but sunlight, and more specifically - full spectrum light, helps to balance Serotonin and Melatonin. When these levels are off, so are we.

Up until fairly recently, doctors would prescribe medication for patients complaining of having "the winter blues." Medications, however, require up to six weeks before a change is felt, and often they come with unwanted side effects.

Researchers at more than 15 medical centers and clinics in both the U.S. and abroad have had much success in using light for seasonal depression in patients with clear histories of SAD for at least several years.

SAD light boxes are designed to mimic the full-spectrum light of the sun. Treatment consists simply of sitting close to the light box with eyes open. Looking at the lights is not recommended. Instead, people are free to engage in such activities as reading and writing, or eating meals.

Light therapy has been shown to have the same capabilities of synthetic drugs in re-stabilizing brain chemistry, but without the side effects, and in a much shorter time. Relief is generally felt within 2 - 5 days.

SAD light boxes have come far in the last decade and there are far more devices available than in years past. If you're in the market for a light for seasonal depression, make sure to do some research before you buy, as size, price and features can vary greatly.