Hypnic jerk

Hypnic jerk
Classification and external resources
Specialty Sleep medicine

A hypnic jerk, hypnagogic jerk, sleep start, sleep twitch or night start, is an involuntary twitch which occurs just as a person is beginning to fall asleep, often causing them to awaken suddenly for a moment. Physically, hypnic jerks resemble the "jump" experienced by a person when startled,[1] sometimes accompanied by a falling sensation.[2] Hypnic jerks are associated with a rapid heartbeat, quickened breathing, sweat, and sometimes "a peculiar sensory feeling of 'shock' or 'falling into the void.'"[3] A higher occurrence is reported in people with irregular sleep schedules.[4]

Causes

According to the American Academy of Sleep Medicine there is a wide range of potential causes, including anxiety, caffeine, stress and strenuous activities in the evening. However, most hypnic jerks occur essentially at random in healthy people.[5]

Another theory is evolutionary, stretching back to our primate ancestors. A study at the University of Colorado has suggested that a hypnic jerk could be "an archaic reflex to the brain's misinterpretation of muscle relaxation with the onset of sleep as a signal that a sleeping primate is falling out of a tree. The reflex may also have had selective value by having the sleeper readjust or review his or her sleeping position in a nest or on a branch in order to assure that a fall did not occur."[6]

During an epilepsy and intensive care study, the lack of a preceding spike discharge measured on an epilepsy monitoring unit, along with the presence only at sleep onset, helped differentiate hypnic jerks from epileptic myoclonus.[7]

According to a study on sleep disturbances in the Journal of Neural Transmission, a hypnic jerk occurs during the non-rapid eye movement sleep cycle and is an "abrupt muscle action flexing movement, generalized or partial and asymmetric, which may cause arousal, with an illusion of falling."[8] Hypnic jerks are more frequent in childhood with 4–7 per hour at the age ranging from 8 to 12 years old, and it decreases toward 1–2 per hour at 65 to 80 years old.[8]

See also

References

  1. ↑ Medical College of Wisconsin, Sleep: A Dynamic Activity
  2. ↑ National Institute of Neurological Disorders and Stroke, Brain Basics: Understanding Sleep
  3. ↑ Why You Sometimes Feel Like You're Falling And Jerk Awake When Trying To Fall Asleep by Lauren F Friedman, Business Insider, May 21, 2014
  4. ↑ Basics of Sleep Behavior: NREM and REM Sleep
  5. ↑ A Case of the Jerks by Kaitlyn Syring, University Daily Kansan, February 28, 2008
  6. ↑ "Why You Sometimes Feel Like You're Falling And Jerk Awake When Trying To Fall Asleep". Retrieved 2016-07-17.
  7. ↑ Fisch, Bruce J. Epilepsy and Intensive Care Monitoring: Principles and Practice. New York: Demos Medical, 2010.
  8. 1 2 Askenasy, J. J. M. (2003). "Sleep Disturbances in Parkinsonism" (PDF). Journal of Neural Transmission. Springer-Verlag. 110: 125–50. doi:10.1007/s007020300001.
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