A sleep study, also known as polysomnography, is a test that monitors various body functions while a person sleeps. It records brain activity, eye movements, heart rate, and breathing patterns to assess sleep quality and diagnose sleep disorders such as sleep apnea, insomnia, or narcolepsy. During a sleep study, patients typically spend the night in a specialized sleep clinic or may use at-home testing devices. Sensors are placed on the body to collect data, which is then analyzed by sleep specialists to determine any underlying issues affecting sleep health.