Objectives: (1) To examine relationships between frequency of nocturia and self-reported sleep quality and objective sleep measures in older women, and (2) to estimate the amount of variation in sleep measures that is specifically attributable to frequency of nocturia. Design and setting: Secondary, cross sectional analysis of the multicenter prospective cohort Study of Osteoporotic Fractures (SOF). Participants: Community-dwelling women aged ≥80 years. Measurements: Frequency of nocturia in the previous 12 months, Pittsburgh Sleep Quality Index sleep quality subscale, and actigraphy-measured wake after sleep onset (WASO) and total sleep time (TST). Results: Of 1,520 participants, 25% (n = 392) reported their nocturia frequency was 3–4 times/night and an additional 60% (n = 917) reported their nocturia frequency was 1–2 times/night. More frequent nocturia was associated with poor sleep quality (3–4/night: 26.8% reported fairly bad or very bad sleep quality; 1–2/night: 14.7%; 0/night: 7.7%; P <.001) and longer WASO (3–4/night: 89.8 minutes; 1–2/night: 70.6; 0/night: 55.5; P <.001). In nested regression models, a nocturia frequency of 3–4/night quadrupled the odds of poor sleep quality (odds ratio: 4.26 [95% CI 1.65, 11.01]; P =.003) and was associated with a 37-minute worsening in WASO (95% CI 26.0, 49.0; P <.001). Frequency of nocturia explained an additional 6% variation in WASO, above and beyond demographic, medical/psychiatric conditions, and medication factors (∆R2 = 0.06). Conclusions: Nocturia is common among octogenarian and nonagenarian women and is independently associated with poor sleep quality and longer wake time at night. Interventions that improve nocturia may be useful in improving sleep quality and wake time at night.