Bed rest is a medical treatment in which a person lies in bed for most of some period of time to gain health benefits. Bed rest refers to voluntarily lying in bed as a treatment, and not being confined to bed because of a health impairment which restricts a person from leaving the bed. The practice is still commonly used for an array of conditions although a 1999 systematic review found no benefits in any of the 17 conditions for which it had been prescribed.