Like most people, you will likely spend a third of your life in bed, and if all goes well, you'll sleep through most of it. But unless you participate in a sleep study, you'll have no clue what goes on while you're checked out, and you might not know how to gauge the quality of your slumber. You may not even have an accurate idea of how long you actually sleep, especially if you don't sleep well.

"People who describe themselves as "good sleepers' are better at estimating how much they have slept, compared to persons who classify themselves as "poor sleepers,'" said Dr. William "Vaughn" McCall, who leads the Department of Psychiatry and Health Behavior at Augusta University's Medical College of Georgia.

So how do you know if you're sleeping well? The best measure of sleep quality — a combination of duration and efficiency — is how you feel the next day, McCall told Live Science.