Nightmares Fluctuate Across the Menstrual Cycle and May be More Pronounced in Women With Premenstrual Syndrome.

Introduction: Premenstrual syndrome (PMS) affects nearly half of women worldwide and is associated with sleep disturbances, though the specific relationship between PMS and nightmares remains underexplored. Clinical observations suggest a potential link, leading this study to investigate whether women with PMS experience more frequent or intense nightmares compared to those without PMS.

Methods: We conducted a prospective case series of seven women experiencing nightmares, all of whom participated in weekly imagery rehearsal therapy (IRT) over 1-month. Each participant completed the daily record of severity of problems (DRSP) to assess PMS symptoms and kept daily dream diaries throughout one menstrual cycle, tracking nightmare frequency, intensity, and emotional valence. The nightmare severity index (NSI) was administered at the beginning and end of the study. Descriptive analysis was used for the dream metrics, and the Wilcoxon signed-rank test was employed to assess changes in NSI scores.

Results: Women with PMS exhibited an increase in nightmare frequency during the premenstrual phase, but no formal statistical comparisons were made between PMS and non-PMS groups regarding dream frequency or intensity. A significant reduction in NSI scores (p = 0.03) was observed across the entire sample, though this effect was not significant in the PMS subgroup.

Conclusions: This case series is the first, to our knowledge, to provide detailed longitudinal data indicating that nightmare frequency may fluctuate across the menstrual cycle and could be more pronounced in women with PMS. While IRT effectively reduced nightmare severity overall, its specific impact on nightmares in women with PMS requires further research in larger studies.