Together, the studies offer a strong argument that seasonal mood changes, which affect about 1 in 5 people, have a biological cause.
This is great new if you suffer from Seasonal Affective Disorder (SAD) because biological causes can be treated, and hopefully in the future, cured. The research supports light therapy as the treatment of choice–a treatment where you are exposed to light from a lamp, which over time improves mood. Now researchers know why: there’s a biological circuit triggered by photoreceptor cells in the eye. Evidently, there are at least three types of cells in the retina: rods, cones, and photoreceptor cells not found in rods and cones. It’s the third type of cell that holds the key to mood because it triggers the brain. So, if you get moody in the winter, there’s a biological cause that can be treated by more light. This is just one more excuse to go on vacation to somewhere tropical; it’s good for your health!