The effect of menopause on objective sleep parameters: data from an epidemiologic study in São Paulo, Brazil.

Objective: Our objective was to investigate the influence of menopausal status on sleep patterns in a representative sample of women from São Paulo, Brazil.

Study Design: A population-based survey with a probabilistic three-stage cluster sample of the city of São Paulo was used to represent the local population according to gender, age (20-80 years) and socioeconomic status.

Main Outcome Measures: The female participants answered a sleep questionnaire, underwent polysomnographic recording and allowed their hormone levels to be measured. They also completed a gynecological questionnaire for classification of the reproductive aging stages: premenopausal or reproductive, perimenopausal or menopausal transition, and postmenopausal, defined as being after 12 months of amenorrhea. Women were allocated into early (the first 5 years after menopause) and late (after the first 5 years) stages.

Results: A total of 535 women were included in this study: 339 were premenopausal, 53 were early postmenopausal, 118 were late postmenopausal and 25 were using hormone therapy or isoflavone compounds. Our main findings were that women in postmenopause spent more time in N3 sleep, had a higher apnea-hypopnea index (AHI) and lower SaO2 compared with premenopausal women after an analysis adjusted for confounding factors. We found no significant differences between early and late postmenopausal women in the adjusted analysis.

Conclusion: Our results indicate menopause itself exerts a modest, but important influence on objective sleep patterns, independent of age, in particular on AHI and SaO2.