4 Signs Your Thyroid Is to Blame for Your Winter Blues

Post daylight savings, reality sets in: You're commuting to and from work in the dark. And, as you know, that lack of sunlight contributes to SAD. "Light exposure causes a whole host of hormonal and mood changes, and some people are exquisitely sensitive to the decreased light," says Romm. If you have SAD, light therapy (sitting in front of a window or using a light box) is often recommended and worth a try, certainly; you should start to feel better in one to two weeks, according to research. Otherwise, something else could be going on—and it may be time to make an appointment for a doctor to look at your thyroid more closely.