Background: Alcohol dependence is known to impact upon sleep, and poor sleep has been shown to affect relapse rates following treatment for alcohol dependence. Aims: The aim of this study was to investigate the association between sleep problems and relapse in dependent drinkers in an inpatient setting. This was done by studying sleep related cognitions in individuals undergoing medically assisted alcohol withdrawal. Method: Sleep and sleep-related cognitions data were collected for 71 individuals undergoing detoxification treatment. Sleep was measured using sleep diaries and actigraph motion monitors. Participants completed sleep-related cognition questionnaires and were subject to telephone follow-up interviews. The results were then used to predict relapse rates 4 weeks after discharge. Results: Longer sleep onset latency recorded on the unit predicted relapse at 4 weeks. Higher dysfunctional beliefs about sleep were found to be associated with lower relapse rates. Conclusions: This study suggests that some dysfunctional beliefs about sleep may support recovery following discharge from treatment. The study further supports the need for tailored cognitive-behavioural treatments for sleep difficulties in this population to reduce relapse rates.