Rates of obesity and sleep disturbances are substantial in adults. A number of cross-sectional, longitudinal, and experimental studies have found that insufficient sleep and possibly longer sleep are associated with obesity and related eating patterns. Methodological discrepancies and limitations in the literature create ambiguity about the nature and potential mechanisms underlying these relationships. Insomnia and circadian patterns in eating and sleeping have also been examined in relation to weight. Although these studies are not as extensive as those examining sleep duration, the extant literature suggests possible associations between obesity and both insomnia (particularly when combined with short sleep duration) and circadian eating behaviours. However, research has only just begun to examine the benefits of combining sleep interventions with obesity treatment. The goal of the current review is to summarize research examining behavioural sleep patterns and disorders in relation to obesity, to discuss methodological considerations, and to provide an overview of studies examining whether addressing sleep disturbances can augment weight loss treatment effects. We conclude that future studies are needed that take into account sleep duration, sleep disorder co-morbidity, and chronobiology to explore the impact of sleep interventions on weight loss.