Polysomnogram (PSG)
A sleep study or polysomnogram (PSG) is a test that electronically transmits and records specific physical activities while you sleep. The recordings become data that are analyzed by a qualified sleep specialist to determine whether or not you have a sleep disorder. Diagnostic overnight PSG: General monitoring of sleep and a variety of body functions during sleep, including breathing patterns along with oxygen levels in the blood, heart rhythms, and limb movements. Diagnostic daytime multiple sleep latency test (MSLT): The MSLT is used to diagnose narcolepsy and to measure the degree of daytime sleepiness. It measures how quickly you fall asleep in quiet situations during the day. It also monitors how quickly and how often you enter REM sleep. To ensure accurate results, it is performed on the morning following a diagnostic overnight PSG. PSG results are used to help diagnose: 1. Sleep-related breathing disorders, such as sleep apnea 2. Sleep-related seizure disorders 3. Sleep-related movement disorders, such as periodic limb movement disorder 4. Sleep disorders that cause extreme daytime tiredness, such as narcolepsy (PSG and MSLT results will be reviewed together) Your doctor also may use a PSG to find the right setting for you on a CPAP (continuous positive airway pressure) machine. CPAP is a treatment for sleep apnea. Sleep apnea is a common disorder in which you have one or more pauses in breathing or shallow breaths while you sleep. In obstructive sleep apnea, the airway collapses or becomes blocked during sleep. A CPAP machine uses mild air pressure to keep your airway open while you sleep.