Polysomnography (PSG) is a study of sleep cycles and sleep behavior. It is usually done in a sleep center overnight. This study involves observing a person at sleep while charting brain waves and other bodily functions.

This study can evaluate sleeping problems, such as:

  • Trouble falling or staying asleep—insomnia
  • Breathing that stops during sleep—apnea
  • A problem with falling asleep suddenly during the day—narcolepsy
  • Nightmares and sleepwalking
  • Problems with arm or leg movement during sleep