A significant weight gain and obesity are observed for most patients with narcolepsy, mainly at the beginning of the disease and narcolepsy in young children. There is no specific study on the population and the consequences of overweight in the lives of these long-term patients. Narcoleptic patients gain weight significantly at the onset of their illness. It is also known that weight gain is not related to the treatment of narcolepsy. The etiology of obesity in narcoleptic patients is not established. Several assumptions were made (physical activity, leptin diet, metabolism). The reason and the pathophysiology of overweight and obesity in this population therefore remain unclear. In this study, potential change in the total metabolism (24h) for narcoleptic children that could explain their tendency to obesity will be assessed ?