ABSTRACTBackgroundYoung adult survivors of childhood cancer exhibit rates of frailty similar to adults several decades older without a cancer history. Frailty has been associated with sleep disturbances in non‐cancer populations, but the relationship has not been examined in childhood cancer survivors who are known to exhibit elevated rates of sleep problems.AimsExamine associations between frailty and poor sleep quality in long‐term survivors of childhood cancer.MethodsThis study utilized data from 9044 participants (> 5 years from diagnosis, Mage = 40.8 years [SD = 9.5]) in the Childhood Cancer Survivor Study. Survivors' frailty status, chronic health conditions (CHC), health behaviors, mental health, and pain were collected in 2014–2016, and self‐reported sleep quality in 2017–2019. Multivariable logistic regression models examined frailty status as a predictor of clinically significant poor sleep. All models were adjusted for age at diagnosis, age at survey, sex, race/ethnicity, smoking, risky/heavy alcohol use, and physical inactivity. Separate models included treatment‐related variables, CHC burden (number/severity), and emotional health/pain as co‐variates.ResultsFrail survivors had 6‐fold (95% CI 4.48–7.96) increased odds of future poor sleep quality. Little attenuation of this association was observed when accounting for cancer diagnosis (Odds Ratio [OR] 5.80, 95% CI 4.47–7.52), treatment exposures (OR 5.80, 95% CI 4.43–7.71), or chronic health condition burden (OR 5.12, 95% CI 3.98–6.59), but adjustment for emotional health/pain (OR 2.88, 95% CI 2.18–3.82) attenuated the association appreciably.ConclusionsFrail childhood cancer survivors have a higher prevalence of clinically significant poor sleep quality. Addressing poor physiologic reserve may impact sleep in frail childhood cancer survivors.