A sleep expert details why you wake up groggy from a nap and how to make the most of your snack-sized slumber.

Not sleeping through the night can not only be frustrating, but it can lead to sleep deprivation and increased levels of stress and anxiety. But you don't need to stare at the ceiling any longer.

Ideally, if you could wait one to two hours [after you wake up] and after cortisol levels rise and start to come back down, that would be the best time to have coffee.” This may also help ...