How to Be Happier in January Than in July

You’re in Bora Bora—that’s what you want your body to believe when you’re lazing under a 10,000-lux, cool fluorescent light box, with eyes wide open, for a half-hour daily. This therapy is commonly prescribed to people who suffer from full-blown seasonal affective disorder (SAD). Clinically, SAD affects about 6 percent of Americans—the majority of these are women in their 20s to 40s—and many more of us suffer from the milder “winter blues.” For the sunshine-deprived, light boxes are available online for $200 or less.

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.