Effects of psychedelics on subjective and objective sleep outcomes: A systematic review and exploratory meta-analysis

Background: Psychedelics, including classic psychedelics, 3,4-methylenedioxymethamphetamine (MDMA), and ketamine, are increasingly investigated for psychiatric disorders, but their effects on sleep remain unclear.

Objectives: To systematically evaluate the effects of these interventions on subjective and objective sleep outcomes and summarize sleep-related adverse events.

Design: A systematic review and exploratory meta-analysis was conducted. Subjective and objective sleep outcomes were synthesized using random-effects models with standardized mean differences (Hedges’ g) and 95% confidence intervals (CI). Meta-analyses were stratified by study design and post-administration assessment phase. Data Sources and

Methods: Embase, PubMed, Web of Science, and the Cochrane Library were searched from inception to March 15, 2026. Eligible studies included adults receiving classic psychedelics, MDMA, or ketamine and reporting subjective or objective sleep outcomes or sleep-related adverse events. Objective sleep measures assessed by polysomnography or actigraphy were extracted when available.

Results: Thirty-two reports representing 30 independent studies and 1,975 participants were included. Evidence for classic psychedelics was limited, with insufficient data for meta-analysis. Controlled MDMA studies during the subacute phase suggested improved subjective sleep quality compared with controls (Hedges’ g = -0.78; 95% CI -1.40 to -0.17; I 2 = 14.4%; very low certainty). Uncontrolled MDMA studies during follow-up also showed within-group improvement (Hedges’ g = -0.63; 95% CI -1.13 to -0.14; I 2 = 0%). Ketamine studies did not demonstrate a statistically significant within-group improvement in subjective sleep quality during the subacute phase (Hedges’ g = -0.45; 95% CI -1.04 to 0.14; I 2 = 88.8%). Sleep-related adverse events were generally mild and transient, including insomnia, hypersomnia, and unpleasant dreams.

Conclusion: Psychedelics may have compound-specific and time-dependent effects on sleep. However, the evidence remains preliminary because of small samples, heterogeneous designs, and limited objective and long-term data.