Patients with seasonal affective disorder who had responded to a standard regimen of daily 10,000-lux light therapy were given a tryptophan-free amino acid beverage plus amino acid capsules was used to deplete tryptophan. The beneficial effects of light therapy in the treatment of seasonal affective disorder were reversed by tryptophan depletion. These findings confirm previous work showing that serotonin plays an important role in the mechanism of action of light therapy.

Arch Gen Psychiatry. 1998;55:524-530

Dr. Mercola's Comment:

I am witting this on the longest day of the year so SAD is not much of an issue. It is interesting to note though that the beneficial effects of light therapy are mediated through serotonin. This is great to know as improving serotonin levels through natural means is quite simple to do. I have been using tryptophan and 5 hydroxy tryptophan with patients for the last several months and I am becoming convinced that the plain tryptophan seems to work best.

Unfortunately the cost of this prescription item is well over $1.00 per day and it is generally not covered by insurance prescription programs. For those of you who are still interested in this natural method to treat depression, I have reprinted the following item on its use from the March 23 newsletter. There is also a new book out called Potatoes Not Prozac which details how one can use dietary manipulations to increase serotonin levels.