Pneumologists frequently see obese and diabetic patients because of the high prevalence of these pathologies associated with sleep apneas. Nevertheless, the search for a sleep apnea syndrome is sometimes negative and the pneumologist is faced with unexplained complaints of sleepiness and sleep disorders. Pneumologists have to be familiar with and explore other nonrespiratory disorders in order to improve patient care. Inflammatory mechanisms have been suspected in several recent studies on daytime sleepiness. Sleep duration, obesity and diabetes are supposed to be linked because of hormonal modifications induced by sleep deprivation. Moreover, a relationship between diabetes and restless legs syndrome is not excluded.