Association of sleep disturbance with Parkinson disease: evidence from the Women's Health Initiative.

OBJECTIVE

To examine the association of sleep disturbance with Parkinson disease (PD) during 10+ years of follow-up among postmenopausal women, 50 to 79 years of age at baseline.

METHODS

Longitudinal data on 130,502 study-eligible women (mean ± standard deviation baseline age = 63.16 ± 7.20 y) from the Women's Health Initiative Clinical Trials and Women's Health Initiative Observational Study were analyzed. The cohort was followed for 15.88 ± 6.50 years, yielding 2,829 (2.17%) PD cases. Sleep disturbance (habitual sleep duration, insomnia symptoms, obstructive sleep apnea risk factors, sleep aids among those with WHI Insomnia Rating Scale scores (WHIIRS) > 9) was measured at baseline and one follow-up time by September 12, 2005. Cox proportional hazards models evaluated relationships controlling for sociodemographic, lifestyle, and health characteristics.

RESULTS

PD was significantly associated with long sleep duration (≥9 h) versus a benchmark of 7 to 8 hours (hazard ratio [HR] = 1.296, 95% confidence interval [CI]: 1.153-1.456), WHIIRS (>9 vs ≤9) (HR = 1.114, 95% CI:1.023-1.214), and use of sleep aids (yes vs no) (HR = 1.332, 95% CI:1.153-1.539) among those with WHIIRS > 9. Compared with 7 to 8 hours, short (<7 h) sleep duration was unrelated to PD. Finally, the presence of obstructive sleep apnea risk factors was not associated with PD.

CONCLUSIONS

Among postmenopausal women, sleep disturbance was associated with approximately 10% to 30% increased PD risk after ∼16 years follow-up. Prospective cohort studies with objective exposures and adjudicated outcomes that include men and women of diverse backgrounds are required to confirm and extend these findings.