Why Do People ‘Twitch’ When Falling Asleep

By on June 5, 2017

2. Why Do People ‘Twitch’ When Falling Asleep?


A hypnagogic jerk is an involuntary muscle spasm that takes place when as a person starts drifting off to sleep.

Named in reference to the hypnogogic state, The phenomena is believed to occur during the transitional period between being awake and unconsciousness. Hypnagogic jerks are also commonly referred to as hypnic jerks or sleep starts.

In many cases the muscle spasms occur spontaneously but may also be induced by sound, light, or other external stimuli. Some individuals report hypnic jerks come accompanied with hallucinations, dreams, bright lights, and even the sensation of falling.

Sleep starts are quite common, between 60% to 70% of people experience them, says Dr. William Kohler, medical director of the Florida Sleep Institute. Many sleep subjects were accompanied by nightly hypnic jerks without their knowledge; as the twitches often go unremembered, particularly if they don’t cause an individual to wake up.

(sources: Cleveland Clinic / Live Science)