[ hahy-per-som-nee-uh ]
/ ˌhaɪ pərˈsɒm ni ə /

noun Pathology.

a tendency to sleep excessively.

Origin of hypersomnia

First recorded in 1875–80; hyper- + (in)somnia

Related forms

hy·per·som·ni·ac, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Medicine definitions for hypersomnia


[ hī′pər-sŏmnē-ə ]


A condition in which one sleeps for an excessively long time but is normal in the waking intervals.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.