This paper reviews the literature regarding the effects of cannabinoid administration on sleep in humans. A literature search using a set of cannabinoid and sleep-related terms was conducted across eight electronic databases. Human studies that involved the administration of cannabinoids and at least one quantitative sleep-related measure were included. Review papers, opinion pieces, letters or editorials, case studies (final N < 7), published abstracts, posters, and non-English papers were excluded. Thirty-nine publications were included in the review. Findings were mixed and showed various effects of cannabinoid administration on several aspects of sleep. Methodological issues in the majority of studies to date, however, preclude any definitive conclusion.