Co-morbid parasomnias in narcolepsy and idiopathic hypersomnia: more REM than NREM parasomnias
- S-Med
- May 13
- 2 min read
In this large, controlled group of adult patients with well-defined NT1, NT2, and IH, current co-morbid NREM parasomnias were as rare as in healthy controls, except for a higher frequency of SRED in the NT1 group. In contrast, REM parasomnias (including by order of frequency, sleep-related hallucinations, sleep paralysis, and frequent nightmares) were more frequent in all groups of patients than in the control group and more frequent in the NT1 group than in other patient groups. Clinical RBD was also more frequent in the NT1 group compared with the NT2 and IH groups, although information on this parasomnia was not available in controls. Treatments influenced parasomnias, particularly in NT1 patients. Antidepressants were more frequently associated with RBD, and sodium oxybate promoted nightmares and NREM parasomnias. Stimulants reduced the risk of sleep paralysis and sleep shouting. In NT2 patients, antidepressants were more frequently associated with RBD, nightmares, and night eating. In the IH group, the prevalence of parasomnias was not affected by medications.
Surprisingly, we found no increased frequency of current NREM parasomnias (except for SRED in the NT1 group) in all groups with central disorders of hypersomnolence. Even if this is a negative and unexpected finding (indeed, it is expected that there is an increased frequency of current NREM parasomnias via higher N3 amounts and sleep inertia in patients with IH, via higher sleep fragmentation in narcolepsy, or via increased anxiety in the 3 hypersomnias), this is new information in the field, suggesting that the association of narcolepsy or IH with NREM parasomnias is by chance. One should note, however, that the 3 groups of patients reported more frequent familial history of NREM parasomnias and personal history of childhood NREM parasomnias than did the control group. Because this historical association of NREM parasomnias and central disorders of hypersomnolence disappeared at the time of the study, one may suggest that (1) patients have a (higher) recall bias of any familial and personal history of sleep disorders because they now experience a severe sleep disorder and (2) the treatments used in central disorders of hypersomnolence may reduce NREM parasomnias. Although nearly half of adults with primary NREM parasomnias have reported excessive daytime sleepiness (at least on questionnaires, but not on the Multiple Sleep Latency Test), the patients with central disorders of hypersomnolence had no higher sleepiness when they had or did not have co-morbid parasomnias, suggesting no common pathophysiology and no additional parasomnia-related sleepiness in patients with NT1, NT2, and IH.
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