Polysomnography is a test that measures many different aspects of the body during sleep and consists of an electroencephalogram which monitors brain-wave activity through the use of electodes attached to the scalp. An electro-oculogram monitors the activity of the eyes, again through electrodes that are placed near the eyes to monitor eye movement which is characterized during REM sleep. An eletromyogram monitors muscle movements and involves a simple procedure of placing a needle in muscles to watch for electrical impulses. All of these tests, and some more, amalgamate to the polysomnography results which can be used to help diagnose sleep disorders.