Ayahuasca is a traditional South American psychoactive beverage and the central sacrament of Brazilianbased religious groups, with followers in Europe and the United States. The tea contains the psychedelic indole N, N-dimethyltryptamine (DMT) and β-carboline alkaloids with monoamine oxidase-inhibiting properties that render DMT orally active. DMT interacts with serotonergic neurotransmission acting as a partial agonist at 5-HT1A and 5-HT2A/2C receptor sites. Given the role played by serotonin in the regulation of the sleep/wake cycle, we investigated the effects of daytime ayahuasca consumption in sleep parameters.