How to Be Happier in January Than in July
But unlike sunlight, the light box doesn’t trigger your body to produce vitamin D, which regulates brain health. As many as one in three of us have clinically low levels in the wintertime, and a deficiency may be related to depression. (People in Scandinavian countries eat a lot of vitamin-D-rich fish, which may explain why they have a lower rate of SAD despite the elusive arctic sun.) If you’re D-deficient and herring’s not to your taste, your doctor will likely recommend a supplement.