National Sleep Foundation

Chapter 1: Normal Sleep

Sleep Function

We know that sleep significantly affects the brain and the rest of the body, and that it is important for physical and emotional health and well-being. Yet, we know surprisingly little about sleep’s specific purpose and function — other than observing that people are less tired, and function better, after a good night's sleep1.  Only in the last 30 years have physicians and scientists systematically explored sleep disorders.

Unfortunately, individuals who do not get adequate sleep lose insight into the effects the sleep deprivation is having on their day-to-day functioning. Given the increasingly fast-paced nature of our society, there is growing concern about the prevalence and effects of sleep deprivation2.


  1. Rechtschaffen A. Current perspectives on the function of sleep. Perspectives in Biology and Medicine. 1998;41:359-390.
  2. Banks S, Dinges DF. Chronic sleep deprivation. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine. 5th ed. Philadelphia: Elsevier Saunders; 2011:67-75.