In rapid eye movement (REM) sleep, pontine cholinergic neurons inhibit motor neurons in the medulla and the descending alpha motor neurons, producing the characteristic atonia of REM sleep. This may be precipitated by sudden withdrawal of anticataplectic medication, for example tricycli antidepressants. Rarely, attacks may be so frequent as to merge together (status cataplecticus). The frequency of attack varies from a few per month to multiple attacks each day. Recovery is generally rapid and complete. An episode of cataplexy typically lasts from a few seconds to approximately one minute. The respiratory and extraocular muscles are unaffected and the sufferer is fully aware throughout, which distinguishes it from epilepsy or sudden collapse from a transient cardiac event. The degree of muscle weakness varies between individuals, ranging from complete loss with collapse to the ground, through unsteadiness (“jelly legs”) to transient drooping of the face. It is one of the principal symptoms of narcolepsy, together with irresistible sleep attacks, hypnagogic hallucinations and sleep paralysis. University Hospitals of Leicester NHS Trustĭr Hanning has received grants in support of research from and has acted as a paid consultant to Cephalon Inc and Orphan Medical IncĬataplexy is a bilateral muscle weakness precipitated by emotion or by the anticipation of the emotion, classically laughter.
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