Recurrent Isolated Sleep Paralysis (ISP) is characterized by an inability to talk or move either at sleep onset or upon awakening, while the person is fully conscious.1 IPS is also characterized by vivid hypnagogic hallucinations (i.e., auditory, visual, or tactile hallucinations).
Episodes usually resolve spontaneously within seconds to minutes and can be curtailed by sensory stimulation (for example, being touched or spoken to) or by an intense effort to move the body.
While paralysis at the onset of sleep may be a sign of narcolepsy, awakening with sleep paralysis is benign. The term “isolated” sleep paralysis is used when the atonia occurs in people without any signs of narcolepsy.
The International Classification of Sleep Disorders (ICSD) lists ISP as a REM-Related Parasomnia.2
- Nielson T, Zadra A, “Idiopathic Nightmares and Dream Disturbances Associated with Sleep-Wake Transitions,” in Kryger M, Roth T, Dement W (ed.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, 2011, pages 1106-1115.
- American Academy of Sleep Medicine, International Classification of Sleep Disorders (Third Edition), Darien, IL: American Academy of Sleep Medicine, 2014.