Nightmares affect the experience of sleep quality but not sleep architecture: an ambulatory polysomnographic study

BACKGROUND Nightmares and bad dreams are common in people with emotional disturbances. For example, nightmares are a core symptom in posttraumatic stress disorder and about 50% of borderline personality disorder patients suffer from frequent nightmares. Independent of mental disorders, nightmares are often associated with sleep problems such as prolonged sleep latencies, poorer sleep quality, and daytime sleepiness. It has not been well documented whether this is reflected in objectively quantifiable physiological indices of sleep quality. METHODS Questionnaires regarding subjective sleep quality and ambulatory polysomnographic recordings of objective sleep parameters were collected during three consecutive nights in 17 individuals with frequent nightmares (NM) and 17 healthy control participants (HC). RESULTS NM participants reported worse sleep quality, more waking problems and more severe insomnia compared to HC group. However, sleep measures obtained by ambulatory polysomnographic recordings revealed no group differences in (a) overall sleep architecture, (b) sleep cycle duration as well as REM density and REM duration in each cycle and (c) sleep architecture when only nights with nightmares were analyzed. CONCLUSIONS Our findings support the observation that nightmares result in significant impairment which is independent from disturbed sleep architecture. Thus, these specific problems require specific attention and appropriate treatment.