All of us have an internal clock that regulates our circadian rhythms, including when we sleep and when we are awake. And light is the single most important factor.

An F may mean failure in school, but the letter earns high marks in your diet. The two biggest dietary Fs — fiber and fermented foods — are top.

If you’re struggling with depression, the most important question about taking an antidepressant is whether it will work. But another question on your mind may be whether it will.