For an activity most of us spend about a third of our lives doing, there’s a lot scientists still don’t understand about ...

Nearly one in five US adults struggle to stay asleep until sunrise — turning the dream of 8 hours of uninterrupted rest into a nightmare. “Waking up in the middle of the night can be annoying, but ...

Cortisol is known as the body’s primary stress hormone, but it has many essential functions. It naturally peaks in the morning to help you wake up and feel alert and then gradually decreases ...

If you've ever woken up feeling groggy and sluggish even after a full night of rest, you might not be getting enough core sleep. What is core sleep? It's a term that encompasses the most restorative ...

(CNN) — Find yourself yawning a lot? Do you need that third or fourth cup of coffee to make it through the afternoon at work? Such signs of sleepiness may be a red flag of a serious sleep deficit that ...

Sign up for CNN’s Sleep, But Better newsletter series. Our seven-part guide has helpful hints to achieve better sleep. You’ve heard the rule: No TV before bed ...