Bed rails are safety devices that are used to help prevent falls from a bed. They are typically metal or plastic bars that are attached to the bed frame and run along the length of the bed, providing a barrier that can prevent someone from rolling or falling off the bed. 

Bed rails can be especially useful for people who have mobility issues or are at risk of falling out of bed, such as the elderly or people with certain medical conditions. They can also be useful for people who have trouble getting in and out of bed, as the rails can provide support and stability. 

It is important to note, however, that bed rails can have some drawbacks and potential risks. If they are not installed properly or if they are used incorrectly, they can cause injury. For example, if a person tries to climb over the rail and gets their leg caught, they could suffer a serious injury. Additionally, some people may feel confined or trapped by bed rails, which could cause anxiety or other negative effects. 

Overall, bed rails can be a useful safety device for people who need them, but they should be used carefully and in consultation with a healthcare provider to ensure that they are being used properly and effectively.