Polysomnography, also called a sleep study, is a test used to diagnose sleep disorders. Polysomnography records your brain waves, the oxygen level in your blood, heart rate and breathing, as well as eye and leg movements during the study.

Polysomnography is usually done at a sleep disorders unit within a hospital or at a sleep center. The test records your nighttime sleep patterns. Polysomnography is occasionally done during the day to accommodate shift workers who habitually sleep during the day.

Reference: By Mayo Clinic Staff,https://www.mayoclinic.org/tests-procedures/polysomnography/about/pac-20394877 , consulted on ,july 6th,2019