Nightmare disorder shows reduced slow oscillation-dominant spindle coupling in NREM sleep (opens in new tab)

Nightmare disorder is historically conceptualised as a rapid eye movement (REM) sleep parasomnia, but evidence also points to altered non-rapid eye movement (NREM) sleep physiology. Here, in a retrospective case-control study, we analysed overnight polysomnography from 26 adults with nightmare disorder and 32 controls using a harmonised event-based EEG pipeline. Nightmare disorder showed reduced frontal slow-oscillation–spindle coupling, whereas delta–spindle coupling was preserved, yielding ...