Black cohosh improves objective sleep in postmenopausal women with sleep disturbance

Sleep problems are prominent after menopause. The aim of our study was to look into the effect of black cohosh on both objective and subjective sleep in early postmenopausal women with sleep complaints.

We performed a randomized, double-blind and placebo-controlled research during a 6-month period. Forty-eight postmenopausal women aged 45-60 years with sleep disturbance were enrolled and received daily administration of either black cohosh or placebo. Polysomnography and the Pittsburg Sleep Quality Index (PSQI) were performed at the initiation and termination of the study, as well as the Menopause-specific Quality of Life questionnaire and estradiol and follicle stimulating hormone tests. Liver and renal functions and breast and pelvic ultrasound were set as safety measures, carried out every 3 months.

Seventy-six women were interviewed, of whom 42 women completed the whole trial. Compared with placebo, black cohosh treatment led to significant polysomnographic changes, including increased sleep efficiency and decreased wake after sleep onset (WASO) duration, and tended to improve PSQI with a medium effect size. On average, 15.8% of WASO duration was reduced in the black cohosh group. Vasomotor and physical domains of life quality were improved compared with placebo. Safety measures did not yield any adverse event assigned to black cohosh.

In early postmenopausal women with a major sleep complaint, black cohosh effectively improved sleep and might be a safe measure in managing menopausal sleep disturbance.