Table 4.

Association between MS and abnormal sleep performance in the Nurse Health Study II

Abbreviations: CI = confidence interval; MS = multiple sclerosis; OR = odds ratio; RLS = restless leg syndrome.

^aPercentage of sleep disorders according to MS status.

^bLogistic regression models were used to compare the difference between women with and without MS, p < 0.05.

^cAdjusted for age (continuous), body mass index (kg/m²), body mass index at age 18, ancestry (Scandinavian, Southern European, other Caucasian, or others), latitude of residence at age 15 (north, middle, or south), smoking status (never smoker, past smoker, or current smoker: cigarettes/day, 1–14 or ≥15), physical activity (quintiles), alcohol intake (g/day: 0, 0.1–4.9, 5.0–9.9, 10.0–14.9, or >15), menopause status (premenopausal, no menstrual periods, or had menopause but now induced by hormones), vitamin D supplement use, iron-specific supplement use, use of antidepressant medicine, use of tranquilizers, history of stroke, myocardial infarction, and hypertension (each yes vs no), and sleep disorders including difficulty falling or staying asleep, feeling sleep inadequate, frequent snoring, sleep time (≤6, 7, or ≥8 hours/24 hours), and frequency of daytime sleepiness that affected daily activities (no, 1–3 times/week, 3–6 times/week, or almost every day). The sleep disorder was excluded from the model when it was the outcome.