Several basic research studies have recently demonstrated the impact of sleep disorders in the occurrence or development of increasing diseases such as obesity, diabetes or hypertension. More recently epidemiological surveys seem to confirm this link. These studies have observed that a total sleep time under 6 hours was associated with an increased BMI, and a higher occurrence of diabetes and hypertension. However theses studies are often prospective cohorts non mainly focussed on sleep. The sleep estimates are subjective and there are many possible biases. More studies are necessary to enlighten the implication of sleep in the development of metabolic disorders.