If you've ever felt spaced out, absent-minded, or unable to focus for no clear reason, that's brain fog. Here are some common causes.

You can finally rest easy—we asked sleep experts to tell us everything they know about the healthy habits that help you sleep better.

They’ve saved millions of lives, but confusion about vaccines can put that progress at risk. Leading infectious disease experts share what to know about vaccines today—and how eliminating deadly diseases is within our reach.