Nightmares are characterized as repeated dysphoric dreams with awakening from sleep causing significant distress and impairment. Nightmares are rarely captured in the sleep lab and previous literature highlights subjective nightmare characteristics. The purpose of this study is to characterize nightmares in patients reporting a nightmare during in-lab video polysomnography (PSG).

This is a retrospective review of 2571 PSGs performed in our laboratory between December 2017 and September 2018. Data collected includes patient demographics, PSG variables (including apnea-hypopnea index (AHI), sleep stages, and arousal indices), a post-PSG questionnaire containing questions about the presence of dreams, medications, and comorbid mental health disorders. PSG analysis of REM sleep without atonia, autonomic hyperactivity preceding an arousal in REM sleep, and video analysis for dream enactment is ongoing.

A nightmare was reported during 125 PSGs by 123 different patients. Preliminary analysis produced a cohort of 17 males and 13 females with age range 24-65 (mean = 36.6). Of these 30, 16 had OSA (mean AHI = 9.16). The average REM latency = 151.4 min, average REM sleep = 16.6%, and average REM arousal index =14.4/hr. Eight patients had a diagnosis of posttraumatic stress disorder and eight patients were prescribed prazosin. Eighteen reported dream at least moderately similar to a memory of a traumatic event and nineteen reported the nightmare to be an accurate replay of a traumatic event or a mix of replay/non-replay events. Seven patients reported at least moderate dream enactment in the lab while 15 did not know if they had dream enactment.

This is the first study to characterize nightmares occurring during in-lab video PSG. The rate of nightmare occurrence during PSG was 4.86% in our study, which approximates the prevalence of nightmare disorder in the general population. More than half of patients in our largely military cohort reported replicative trauma related nightmares. Our data suggests nightmares may be more common in the monitored setting than previously thought. Analysis of REM sleep may reveal objective evidence of reported nightmares that is often overlooked.

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