You're correct, and while I was incorrect that filtered bright lights were useless, sitting in front of UV lights for a short duration won't fuck you up in all kinds of ways. UV light therapy does increase the risk of skin cancers and the like, but it's also used to treat certain skin disorders that require UV rays as well as depressive disorders and is typically only prescribed for short time frames (5-20 minutes a day).
When used in a clinical setting, the UV lights from unfiltered light boxes emit UV that replicates the UV radiation intensity of the sun. If you're using a commercial light box that doesn't filter UV, you should be buying one that does the same.
UV from the sun isn't bad, it's only bad in excess. Unfiltered UV (typically from the sun, but also from UV light boxes) is needed to produce many of the D Vitamins. Vitamin D deficiencies typically increase during the winter months when UV rays aren't available for as long as they are during the summer months and are typically available when most people are inside at work.
However, if a Vitamin D deficiency isn't present, many studies have shown that there is no significant difference in the results of UV filtered and UV allowed light therapy when treating SAD. Therefore, as you said, the less dangerous UV filtered light should be used.
You're right that this isn't pseudoscience, but you're wrong that light boxes have nothing to do with Vitamin D production. Light boxes that don't filter UV light are used in treating people that have difficulty absorbing vitamin D3 (specifically during the winter months). The UV lamps that create UV radiation similar to that of the sun allow production and absorption of vitamin D3, see
here.
Additionally, low levels of vitamin D3 are thought to be a cause of Major Depressive Disorder along with other depressive disorders such as SAD. Study results are mixed.
Here is one in support of increased vitamin D3 improving mood in those afflicted with SAD and other depressive disorders. You'll need a subscription to read the full study. And
here is a good overview of the physiology and pharmacology behind D3 and depression. It has a good list of studies in the references section that support and do not support the D3-depression link.
As far as Vitamin D production goes, you only need 5-15 minutes in the sun each day to get required amount of D3, however, in the winter months people with absorption problems typically need a supplement or UV light therapy in order to absorb enough of the vitamin.
The melatonin / serotonin stuff is pretty much spot on. That being said, the increase of one and the decrease of the other may have nothing to do with an individual's light cycles. There are many reasons why too much melatonin and not enough serotonin during the day could be present. It could have to do with faulty receptors or production glands, increased stress, infection, injury or numerous other things. In other words, it's best to get an opinion from someone with medical training.
This is sound advice for anything, and probably the most important takeaway from the entire thread.
Anyway, I'm not trying to be a dick, but Bio-Psych (which is what this boils down to) is what my formal education is based in and there's usually more going on biologically than just having having too much of one hormone and not enough of another.
And by the way dchuk - Did you get my fiction recommendations? Master and Margarita is the one I would suggest first.