A gonadotropin-releasing hormone agonist model demonstrates that nocturnal hot flashes interrupt objective sleep.

OBJECTIVES: Sleep interruption is often reported by women with hot flashes and night sweats (or vasomotor symptoms, VMS). Although women report that VMS awaken them, polysomnography (PSG) studies have not consistently supported this contention.
DESIGN: We mimicked menopause using a gonadotropin-releasing hormone agonist (GnRHa) to investigate whether VMS increase awakenings and wake after sleep onset (WASO). VMS, serum estradiol, and at-home PSGs (two pretreatment, two posttreatment) were measured before and after 4 weeks on GnRHa. Regression models were used to determine the effect of increasing VMS frequency on awakenings and WASO, as measured objectively and subjectively. PARTICIPANTS: Twenty-nine healthy women (mean 27.3 y).
SETTING: Academic medical center.
INTERVENTIONS: Depot GnRHa (leuprolide 3.75-mg).
RESULTS: Serum estradiol was rapidly and uniformly suppressed on GnRHa. Persistent VMS were reported by 69% of women. The number of nighttime VMS correlated directly with the degree of sleep disturbance. Each additional reported nighttime VMS was associated with a 62% increase from baseline in PSG-measured WASO (P = 0.007), a 3% increase in awakenings (P = 0.05), and 6% increase in %N1 sleep (P = 0.02). Nighttime VMS were also associated with increased perceived WASO (312%; P = 0.02), awakenings (16%; P = 0.007), Insomnia Severity Index (P = 0.03), and Pittsburgh Sleep Quality Index (P = 0.03) scores, and decreased perceived sleep efficiency (P = 0.01). Objectively recorded nighttime VMS correlated with PSG-measured WASO (rs = 0.45, P = 0.02).
CONCLUSIONS: This menopause model demonstrates that nighttime vasomotor symptoms correlate with increased sleep fragmentation. These findings are consistent with a specific contribution of vasomotor symptoms to polysomnography-measured sleep interruption suggesting that nighttime vasomotor symptoms interrupt sleep in the setting of menopause.