Dr. Saidi Oussama is researcher at the Tunis university. The overall focus of Saidi Oussama research is the study of interaction between lifestyle behaviors mainly physical activity, nutrition and sleep among adolescent populations (especially high-level athletes or those with chronic illnesses).Saidi Oussama conduct clinical research combining his expertise on sleep, nutrition, and energy balance regulation to address questions relating to the role of circadian rhythms, on physical and cognitive performances.