Nightmare sufferers show atypical emotional semantic associations and prolonged REM sleep-dependent emotional priming

The objective of this study was to investigate whether nightmare (NM) sufferers exhibit an abnormal network of emotional semantic associations as measured by a recently developed, rapid eye movement (REM) sleep-sensitive, associational breadth (AB) task.

NM sufferers were compared to healthy controls (CTL) for their performance on an emotional AB task containing positive and negative cue words both before and after a nap with REM sleep. AB was assessed in both a priming condition, where cue words were explicitly memorized before sleep, and a non-priming condition, where cue words were not memorized. Performance was assessed again 1 week later.

The study was conducted in a sleep laboratory with polysomnographic recording at the Hôpital du Sacré-Coeur de Montréal

Twenty-eight participants between the ages of 18 and 35 years (Mage = 23.3 ± 3.4) were included in the study.

The NM group scored higher than the CTL group on both positive and negative AB, with group differences persisting at the 1-week retest. However, the two groups did not differ as expected in the AB priming effect following REM sleep. Both groups showed decreased REM sleep-related AB priming for negative cue words and increased AB priming for positive cue words. However, the NM group maintained these effects 1 week later, whereas the CTL group did not.

NM sufferers may access broader than normal emotional semantic networks in the wake state, a difference that may lead to this group being perceived as more creative. The fact that the AB priming effect is maintained at the 1-week retest for NM sufferers suggests that the presence of frequent NMs may alter REM sleep-dependent emotional processes over time.