Identifying abnormal nocturnal eating is critically important for patient care and public health. Obesity is a global pandemic and a leading cause of preventable mortality in the United States, with more than 100,000 deaths annually. Normally, nighttime energy homeostasis is maintained, despite an absence of food intake, through appetite suppression and alterations in glucose metabolism that result in stable energy stores. Two conditions break this nighttime fast and are associated with weight gain as well as medical and neuropsychiatric comorbidities. Sleep-related eating disorder (SRED) is characterized by isolated nocturnal eating, whereas the night-eating syndrome (NES) is a circadian delay in meal timing leading to evening hyperphagia, nocturnal eating, and morning anorexia. Recently, SRED has been associated with the benzodiazepine receptor agonist zolpidem. Both SRED and NES are treatable and represent potentially reversible forms of obesity. In SRED, the antiseizure medication topiramate and dopaminergics have both demonstrated promising results. Nocturnal eating associated with NES has responded well to sertraline.