Midlife Women's Responses to a Hospital Sleep Challenge: Aging and Menopause Effects on Sleep Architecture

Abstract

Objective: To distinguish aging from menopause effects on sleep architecture, we studied an episode of disturbed hospital sleep in asymptomatic midlife women during the follicular phase of an ovulatory cycle and three control groups differing by age or menopause status. Methods: Fifty-one studies were conducted in four groups of volunteers: young cycling (YC, 20-30 years, n = 14), older cycling (OC, 40-50 years, n = 15), ovariectomized receiving estrogen therapy (OVX, 40-50 years, n = 12), and spontaneously postmenopausal (PM, 40-50 years, n = 10). Subjects were admitted to the University Hospital General Clinical Research Center (GCRC) for a first-night sleep study conducted during a 24-hour, frequent blood sampling protocol. Results: Despite similar estrogen concentrations in the YC (28 ± 4 pg/ml) and OC (34 ± 6 pg/ml) groups, OC women had reduced sleep efficiency (79% ± 2%) vs. YC (87% ± 3%; p = 0.009). In the OVX and PM groups where estrogen concentrations were markedly different, sleep efficiency was also reduced vs. the YC group (OVX vs. YC, 79% ± 3% vs. 87% ± 3%, p = 0.05; PM vs. YC, 75% ± 3% vs. 87% ± 3%, p = 0.007). Wake time was longer in the three older groups (103 ± 10 minutes, 101 ± 12 minutes, 123 ± 12 minutes for OC, OVX, PM, respectively) vs. YC (63 ± 13 minutes, p < 0.05). The number of stage shifts was positively associated with advancing age (rho = 0.3, p < 0.03) but not with estrogen concentration. Conclusions: Aging-related sleep deficits in response to an experimental stressor occur in midlife women prior to menopause.