Bed rest, also referred to as the rest-cure, is a medical treatment in which a person lies in bed for most of the time to try to cure an illness. Bed rest refers to voluntarily lying in bed as a treatment and not being confined to bed because of a health impairment which physically prevents leaving bed. The practice is still used although a 1999 systematic review found no benefits for any of the 17 conditions studied and no proven benefit for any conditions at all, beyond that imposed by symptoms.

In the United States, nearly 20% of pregnant women have some degree of restricted activity prescribed^{[better source needed]} despite the growing data showing it to be dangerous, causing some experts to call its use "unethical".

Extended bed rest has been proven to be a potentially harmful treatment needing more careful evaluation.

Women who are pregnant and are experiencing early labor, vaginal bleeding, and cervix complications have been prescribed bed rest. This practice in 2013 was strongly discouraged due to no evidence of benefit and evidence of potential harm.

Evidence is unclear if it affects the risk of preterm birth and due to potential side effects the practice is not routinely recommended. It is also not recommended for routine use in pregnant women with high blood pressure or to prevent miscarriage.

Women pregnant with twins or higher-order multiples are at higher risk for pregnancy complications. Routine bed rest in twin pregnancies (bed rest in the absence of complications) does not improve outcomes. Bed rest is therefore not recommended routinely in those with a multiple pregnancy.

Use in combination with assisted reproductive technology such as embryo transfer is also not recommended.

For people with back pain bed rest has previously been recommended. Bed rest, however, is less beneficial than staying active. As a treatment for low back pain, bed rest should not be used for more than 48 hours.