National Sleep Foundation

Glossary

K

K-complexes - A sudden increase in wave amplitude that occurs as a person moves from stage 1 to stage 2 sleep.

Kleine-Levin Syndrome (KLS) - Also called “Sleeping Beauty disease,” a hypersomnia characterized by recurrent episodes of hypersomnia in which patients sleep for 12-24 hours a day. Patients may sleep for days, weeks, or months, waking only to eat and/or use the bathroom.