Sleep starts (hypnic jerks) are sudden, brief jerks that occur when a person is falling asleep.34 They are often associated with a subjective feeling of falling, a sensory flash, or a sleep-onset dream.35 Between 60 and 70 percent of the public experiences sleep starts.36
Although simple sleep starts are benign, there are more complex motor behaviors that may be associated with, or misinterpreted as, “sleep starts” that might be symptomatic of a more serious condition, such as restless legs syndrome.37
The etiology of sleep starts is not understood, but they can be precipitated by an increase in caffeine intake or intense physical activity just before bedtime.
Sleep-onset insomnia and/or sleep deprivation may occur if sleep starts become repetitive or intensified. In such cases, short acting hypnotics may be prescribed to facilitate sleep onset. 38
- 34Thorpy MJ, “Classifications of Sleep Disorders,” In Kryger M, Roth T, Dement W (ed.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, page 687.
- 35Thorpy MJ, “Classifications of Sleep Disorders,” In Kryger M, Roth T, Dement W (ed.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, page 687.
- 36American Academy of Sleep Medicine (AASM). International Classification of Sleep Disorders, 3rd edition: Diagnostic and Coding Manual. Darien, IL: AASM, 2014.
- 37National Institute of Neurological Disorders and Stroke, Myoclonus Fact Sheet, Bethesda MD: NIH, 2014. http://www.ninds.nih.gov/disorders/myoclonus/detail_myoclonus.htm
- 38Sander HW, Geisse H, Quinto C, Sachdeo R, Chokroverty S, “Sensory sleep starts,” J Neurol Neurosurg Psychiatry 1998;64:690.