1. Health
You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

Definition of K-complex


Updated February 19, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.


A characteristic high amplitude waveform that is observed in brain waves as recorded on electroencephalography (EEG) during stage 2 of non rapid-eye movement (NREM) sleep. It has a sharp negative deflection followed by a slower, positive component. The duration is defined as lasting at least a half second. Although they may occur spontaneously, K-complexes can also be elicited during sleep in response to auditory stimuli. It often occurs in stage 2 sleep with another waveform called a sleep spindle.

Alternate Spellings: K complex
Looking at the sleep study, it was clear that he was in stage 2 sleep because of the presence of K-complexes.
  1. About.com
  2. Health
  3. Sleep
  4. Have a Sleep Disorder?
  5. Definition of K-complex

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.