A multifactorial etiology for narcolepsy has been postulated, stressing the importance of environmental factors in the clinical onset of the condition. Our study evaluated the occurrence of stressful life events in the year preceding the onset of narcolepsy. Fifty narcoleptic and 50 control subjects completed a life event questionnaire (the Schedule of Recent Experiences). The proportion of narcoleptic subjects reporting the presence of life events in the year preceding the onset of narcolepsy was significantly greater than the proportion of control subjects reporting life events in the corresponding year. Moreover the weight of life events was increased in narcoleptic subjects in comparison with controls. In conclusion life events seem to be increased in narcoleptic subjects in the year preceding the onset of their condition. However a number of other factors could not be taken into consideration, which limits the full significance of these data.