For starters, a study published in the current issue of the American Journal of Physiology-Endocrinology and Metabolism suggests that using your weekend to sleep in actually doesn't fix all the damage caused by missing out on some slumber during the week.

"The major take away message is that extended sleep helps, but only to some extent," study co-author Dr. Alexandros Vgontzas, professor at Penn State University's Hershey Sleep Research & Treatment Center, told The Huffington Post in an email. "The repeated cycle of restriction/recovery may be harmful to your health in the long run."