This study addresses whether ecstasy, a widely used recreational drug, adversely affects sleep, because any marked shortening of sleep could contribute to the emotional, social and intellectual deficits that occur in the days after taking the drug. The study also addresses whether ecstasy causes impaired learning of skills. Current ecstasy users as well as abstinent ecstasy users are involved in the study, and are compared to non-ecstasy polydrug using controls. The study also investigates the integrity of the memory consolidation and enhancement function of post-learning sleep in the participants. This follows from recent work with non drug taking healthy individuals that shows how a period of sleep in the night after training can lead to an enhancement of memory beyond the level seen immediately after training, and beyond the level seen if testing occurred after a similar period of wakefulness. The study will have important implications for advice to policy makers and drug users about the harmful effects of ecstasy, for advice to educators and employers about the work training needs of people who take drugs, and, at the theoretical level will have important implications for the rapidly expanding field of the investigation of the memory enhancement function of sleep.