National Sleep Foundation

Glossary

E

Endocrine System - The collection of glands that secrete hormones into the circulatory system and are carried to another organ), which has a complex response to sleep. Secretion of some hormones increases during sleep (e.g., growth hormone, prolactin, and luteinizing hormone), while secretion of other hormones is inhibited during sleep (e.g., thyroid stimulating hormone and cortisol).

Excessive Daytime Sleepiness (EDS) - Sleepiness that interferes with daytime functioning; this can result from sleep deprivation, insomnia, narcolepsy (disabling sleepiness), or cataplexy (sudden muscular weakness). EDS can manifest itself as a tendency to fall asleep during normal waking hours when unstimulated and is objectively diagnosed when the average sleep latency on the Multiple Sleep Latency Test drops below 8 minutes. EDS and “hypersomnia” are currently used interchangeably.

Expiratory Positive Airway Pressure (EPAP) - Treatment device used for obstructive sleep apnea that involves securing a disposable valve inside the person’s nostrils that facilitates airflow.