Introduction:Since sleep pattern and time management are essential factors for the success of students, knowing the sleep wake patterns and prevalence of sleep disturbances among medical students would help to recognize and scrutinize the consequences of these disturbances of sleep on academic, psychological, social and medical parameters.Aim:To describe sleep habits and sleep disorders among medical students and the consequent effects on students' performance and psychological stress.Methods:This is a cross sectional study involving the clinical year Medical students during the 2011-2012 academic year. Students were randomly selected and interviewed individually by trained physicians using a questionnaire collecting data on the following: The Pittsburgh Sleep Quality Index (PSQI), The Epworth Sleepiness Scale (ESS) and The Perceived Stress Scale (PSS)Results:A total of 305 students were recruited, 58.4% (178) of them were females. A total of 69.5% (212) of the students had a disturbed and poor sleep quality. Excessive daytime sleepiness was reported by 38.7% (118) of students. There was no genders difference regarding the sleep disturbances and ESS (p:0.663 and p:0.143 respectively). However, 64.9% (198) of students were found to be stressed, more among females (p: <0.01). There was a strong association between stress and disturbed sleep since 72% of students with poor sleep quality are stressed (p: 0.001). There was no impact of sleep disturbances or stress on the academic performance.Conclusion:Sleep disturbances and poor sleep quality are very common among medical students at clinical years. Although these disturbances were associated with increased stress but showed no significant impact on academic performance.