Sleep Specialist Overview. A sleep specialist is a medical doctor who has completed additional education and training in the field of sleep medicine. Sleep medicine focuses on sleep, sleep disorders, and sleep-related conditions, and is a subspecialty within several medical specialties, including neurology, pulmonology, internal medicine,...

This is the medical term for sleeping too much and for excessive daytime sleepiness. Much like insomnia (sleeplessness), sleeping too much is a sign of disordered sleep. Hypersomnia is diagnosed when excessive sleep has no known explanation.

Sleep: The body's rest cycle.. Sleep is triggered by a complex group of hormones that are active in the main, and that respond to cues from the body itself and the environment. About 80 percent of sleep is dreamless, and is known as non-rapid eye movement (NREM) sleep. During NREM sleep, the breathing and heart rate are slow and regular, the blood pressure is low, and the sleeper is relatively ...

Polysomnography (sleep study): 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.