It is far better to bore out the hole than whittle down the peg. If it is S.A.D. then there are ways to increase one's daily exposure to full-spectrum sunlight that do not involve an expensive change in lattitude.

The problem with chemically tweaking yourself is it reaches a point where it seems to me it would be difficult to decide which was the proper course of action: is it a "natural" negative emotion, which should be dealt with by a change in behavior, or is it a "pathological" negative emotion which can be dealt with by breaking it with a pharmecological mallet?