ANNOUNCER: There's a chill in the air; leaves are falling off trees and daylight is getting shorter. And then it is winter. For some, this seasonal change is a time of joy, but for people with seasonal affective disorder or SAD, 'tis the season for depression.
MICHAEL TERMAN, PhD: It usually starts off with feelings of fatigue, difficulty getting up in the morning, a big afternoon slump, and then a taste for carbohydrate-rich foods. Coupled with that fatigue and the carbohydrate-rich food that's a formula for weight gain.
One of the classic symptoms is what we call hypersomnia, significantly longer sleep than you sleep in the summer.
ANNOUNCER: Other symptoms include mood changes, loss of interest in activities one would usually enjoy, difficulty concentrating, social withdrawal and decreased sex drive.
MICHAEL TERMAN, PhD: You put all those together in the time course of fall, winter, and early spring, and that's seasonal affective disorder, or SAD.
ANNOUNCER: Some people would say, this sounds like a case of the "holiday blues" but there's a difference.
MICHAEL TERMAN, PhD: They can say to themselves, I'm bad at this time every year, and I'm fine in the summer. They'll know, however, that it isn't some emotional connection with the holidays that's triggering their depression if it doesn't let up until April or May, because a holiday depression will pass shortly after New Year's.
ANNOUNCER: The cause of SAD is unknown, but research suggests where you live may make play a role.
MICHAEL TERMAN, PhD: SAD is widely prevalent throughout the population, and it's the worst the further north you go. In the middle tier of the United States, up until southern Canada, it's far more prevalent than in the south of the United States.
ANNOUNCER: Theories suggest the shorter days during the winter months throws a wrench in the works of the biological clock.
MICHAEL TERMAN, PhD: Our nervous system relies on a daily exposure to early morning light in order for the internal biological clock to stay synchronized with the external world. So when we allow our internal clock to drift later and later as sunrise drifts later and later and the days grow shorter, that's when we see the onset of all of these symptoms.
ANNOUNCER: Melatonin, a hormone involved in the sleep cycle has also been linked to winter depression.
MICHAEL TERMAN, PhD: Melatonin is a nighttime hormone. The nights are longer in the winter, and so our biological clock turns on melatonin earlier and turns it off later. Some people will start to sleep 12 or 13 or 14 hours.
ANNOUNCER: And similar to other forms of depression there may be an imbalance in the brain chemical that is involved in regulating mood.
MICHAEL TERMAN, PhD: What we realize now is that the whole gamut of depressions, whether seasonal or not, is modulated by the level of serotonin activity in the brain.
ANNOUNCER: So how do doctors diagnose SAD? For some, that might take a little investigating.
MICHAEL TERMAN, PhD: The first question to ask is, how were you feeling in June and July? Next question to ask is, how were you feeling at this time last year and the year before? Third question to ask is, if you add up all your winters and all your summers, how much more likely have you been depressed at this time of year than at the alternate time of year?
ANNOUNCER: People suffering from SAD can do some prep work by filling out an inventory of their symptoms. An automated form can be found on www.cet.org.
MICHAEL TERMAN, PhD: It's called the "Personal Inventory for Depression and SAD," and it asks you symptom by symptom what you have and when you have it, and how severe is it?
ANNOUNCER: Once a diagnosis is made, SAD sufferers can begin to see the light.
MICHAEL TERMAN, PhD: Primary is bright light therapy in the morning after you wake up. When we use bright light therapy. It's a level equal to outdoor light about 40 minutes after the sun rises. There are light receptors in the eyes that are specialized for sending signals to the biological clock. So it resets the clock to its springtime mode, and that's when we begin to see the alleviation of symptoms. The average treatment duration that is adequate for most people is 30 minutes.
ANNOUNCER: In addition to light box therapy other options are available.
MICHAEL TERMAN, PhD: Options include dawn simulation therapy, in which you force an artificial sunrise in your bedroom while it's still dark outside.
Another option is negative air ionization therapy, in which you create summer-like conditions in the circulating air environment, either while you sleep or during the day.
Another option is standard antidepressant medication, which you really need to use only during the difficult months of the year, not all year long.
ANNOUNCER: Lastly, good old-fashioned psychotherapy is recommended.
MICHAEL TERMAN, PhD: There are indications that cognitive behavioral therapy can be effective in helping people deal with the challenges of winter and lifting their mood and improving their function.
ANNOUNCER: There is no cure for seasonal affective disorder but the treatments available can alleviate the symptoms and greatly improve quality of life until the buds of spring appear.