melatonin

The drowsiness that arrives every October has more to do with light than temperature, and the warm room may be doing more harm than the cold outside.

Summer-pattern seasonal affective disorder is the lesser-known, agitated opposite of winter depression -- real enough for NIMH's diagnostic criteria, but still short on answers about its cause.

A bottle of melatonin in an American drugstore can pack five to ten milligrams; the same supplement in France is capped under two. The regulatory gap has real consequences for how families use -- and mis-store -- a hormone most people assume is harmless.