Poor sleep patterns are common in undergraduates and may turn them prone to mood disorders, substance abuse and impaired academic performance. The aim of this study was to assess sleep disturbances among medical students, and whether associations with academic performance, depressive symptoms or substance use were present.Cross-sectional study in which 544 medical students of the Pontificia Universidad Javeriana in Bogota, Colombia were included. Using a computer-based survey, self-reported variables were assessed, including demographics, Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Berlin Questionnaire, Diagnostic and Statistical Manual of Mental Disorders (DSM) - IV depression criteria, Grade Point Average (GPA), and substance use. Associations between these variables were obtained.Fifty-four percent of students were women. Poor sleep quality (PSQI>5) and daytime sleepiness (ESS>10) were found in 65% of the population. A higher GPA was more frequent in students with good sleep quality (OR= 2.6 [1.5-4.5]), lack of daytime sleepiness (OR= 2 [1.3-3.1]) and low risk of Obstructive Sleep Apnea Syndrome (OSAS) (OR= 3.1 [1.6-5.9]). DSM-IV depression criteria were fulfilled by 26% of the students and were associated with poor sleep patterns. Energy drinks use was associated with poor sleep quality.Poor sleep quality, daytime sleepiness and depressive symptoms are frequent among medical students and are associated with lower academic performance. The identification of students at risk and the implementation of targeted interventions are warranted. Fostering adequate sleep habits and training on sleep medicine may partly counteract these issues.