Information on Sleep Disorders
(Adapted from the International Classification of Sleep Disorders,  American Academy of Sleep Medicine  2006.)

DEFINITIONS

Apnea- cessation of breathing

Alveolar- pertaining to the alveolus which is an air sac in the lungs

Cataplexy- sudden loss of muscle tone which may cause sagging of the jaw, knee buckling, or collapsing to the ground

Circadian- used to describe a pattern occurring around a 24 hour cycle

Circadian Rhythm- a rhythm which occurs about the 24 hour day/night cycle

Congenital- present since birth

Crescendo/Decrescendo- A cyclic pattern of increasing and decreasing activity

Dissociative disorder- a psychiatric illness often associated with trauma or post traumatic stress disorder. One type was formerly called Multiple Personality disorder.

Extrinsic- coming from outside the body

Hypertension- High blood pressure

Hypopnea- Shallow breathing

Hypoventilation- slow and/or shallow breathing which can lead to a buildup of carbon dioxide and a decrease in oxygen

Hypoxemia- a low oxygen level in the blood

Idiopathic- of unknown cause

Intrinsic- wholly pertaining to inside the body

Multiple Sleep Latency Test- A series of 4-5 naps during the daytime which determine how much sleepiness an individual has compared to normal subjects. It also monitors what stage of sleep someone enters during the nap as part of an assessment for narcolepsy.

MSLT- abbreviation for Multiple Sleep Latency Test

Myoclonus- A sudden jerk or twitch

Neurologic- relating to the nervous system

Nocturnal- occurring at night as opposed to during the day

Oxygen saturation-a non-invasive method of monitoring oxygen levels by pulse oximetry

Physiologic- relating to the way that living things function, rather than to their shape or function

Polysomnography- a non-invasive overnight test which monitors numerous physiologic parameters relating to sleep including EEG (Electroencephalogram) which monitors brain wave activity to differentiate wakefulness from the 5 different sleep stages, EMG (electromyography) which monitors muscle activity in the leg and chin muscles, EOG (electrooculogram) which monitors eye movements, EKG(electrocardiogram) which monitors heart rhythm, airflow and effort detectors to determine if breathing is normal, shallow or absent (apnea) and Pulse Oximetry which monitors oxygen saturation levels.

PSG- abbreviation for Polysomnography

Pulmonary Parenchymal- this pertains to lung tissue generally not including large airways