Seasonal affective disorder is a major (serious) form of depression that occurs at the same time each year. Researchers have identified two types of SAD. The most common type, known as "winter depression," usually begins in the late fall to early winter months and ends in spring. Seasonal affective disorder can also occur in the summer (known as "summer depression").

Surveys estimate that 4 to 6 percent of the general population experience SAD. Women with SAD outnumber men four to one. The disorder usually begins in person's early twenties and the risk for developing SAD decreases with age (Saeed and Bruce). * the symptoms of seasonal affective disorder?

# ncreased sleep # Increased appetite # Weight gain # Irritability # Interpersonal difficulties (especially feelings of rejection) # A heavy leaden feeling in the arms and legs

The exact cause of SAD is unknown, but researchers suspect changes in the availability of sunlight plays an important role. Statistics show that winter depression becomes increasingly more common the farther people live north or south of the equator. Episodes of winter depression also tend to be longer and more severe at higher latitudes (Saeed and Bruce).

Circumstances supporting the first-line use of light therapy5

* The patient is not severely suicidal. * There are medical reasons to avoid the use of antidepressants. * Patient has no history of significant negative effects to light therapy. * The patient requests light therapy. * An experienced practitioner deems that light therapy is indicated.

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Q: Both depression & cognitive problems are common in ms. I started using bright lights (used in seasonal affective disorder) 1.5 weeks ago. My dr told me SAD lights are thought to alter the serotonin levels in the brains. Is it correct that ms also alters serotonin levels? Some of my cognitive problems are improving and I wonder if lights might help ms people with either depression or cognitive issues? Don't panic, I'm not suggesting the lights are a cure-all for ms. I'm suggesting they might be a helpful tool for some of us.

I shouldn't even be posing this question today because I slept less than 5 hrs last night and am functioning like my old foggy headed self today. The areas of improvement (except today) is that I can focus, retain longer # sequences & other info, and am having little word finding difficulty. Wake with more energy & sleep better than usual. I'm hoping today is an anomoly and I will be improved again in the morning. In fact, I hope anomoly is the appropriate word. Any thoughts?

A: If your problem really has anything to do with depression (seasonal or otherwise) then the light, which may very well be raising your brain's serotonin levels, could certainly be responsible (at least in part) for the improvement in your cognitive function.

I have one available to me at the local clinic (all I have to do is sign a book to reserve a time to use it,) and I've several times thought it might be a good thing to give it a try. Haven't done it yet, though. :(

Anyhow, since MS often seems either to induce some sort of endogenous depression or to produce situations about which it's easy to become depressed, I'd be willing to believe that SAD lights could be of at least *some* help to a great many people with MS, even if they haven't any effect on MS itself.

The fact that I'm "willing to believe" technically doesn't mean squat though.