In a crossover trial, adults with insomnia showed no notable next-day impairment in cognitive function, psychomotor performance, or simulated driving after taking 10mg THC + 200mg CBD oil the previous evening.
Insomnia patients considering cannabis, prescribing clinicians, and driving safety policymakers
27 of 28 tests showed no next-day impairment vs placebo
What the researchers found
At 9+ hours after evening administration of 10mg THC/200mg CBD oil, there were no differences from placebo on 27 of 28 cognitive and psychomotor tests, including simulated driving performance. The only difference was a small 1.4% decrease in accuracy on the easy Stroop task (but not the hard version). A slight increase in self-rated sedation at 10 hours was not accompanied by changes in alertness or sleepiness ratings.
Why it matters
A major concern with medicinal cannabis for sleep is next-day impairment affecting driving and work safety. This study provides reassuring evidence that a typical medicinal dose does not produce meaningful next-day functional impairment in an insomnia population.
The numbers in context
20 participants (16 female). Dose: 10mg THC + 200mg CBD oral oil. 27 of 28 tests showed no difference from placebo at 9+ hours. One small effect: -1.4% accuracy on easy Stroop (d=-0.6). Self-rated sedation slightly increased at 10h (d=0.3).
How the study worked
Randomized, double-blind, placebo-controlled crossover trial with 20 adults (16 female, mean age 46.1) with physician-diagnosed insomnia who infrequently use cannabis. Each completed two 24-hour in-lab visits with 10mg THC/200mg CBD oil or placebo, with next-day testing at 9+ hours post-dose.
What this study cannot tell us
Small sample (n=20). Only one dose tested. Participants were cannabis-infrequent, so regular users may differ. Laboratory setting may not capture real-world conditions. The study examined a single dose, not cumulative effects of nightly use.
How to read the evidence
Well-designed double-blind crossover RCT, though limited by small sample and single-dose design.
When this study was published
2024 study
The bigger picture
With increasing use of medicinal cannabis for sleep, evidence about next-day safety is critically needed for clinical guidelines and policy decisions around driving and workplace safety.
Questions still open
- Would higher THC doses or THC-dominant products show different next-day effects? How does regular nightly use change the picture? Would real-world driving tests confirm the simulated driving findings?
Common questions
Can I drive the morning after taking cannabis for sleep?
Does medicinal cannabis for insomnia cause a hangover effect?
Read the original research
Evaluating possible 'next day' impairment in insomnia patients administered an oral medicinal cannabis product by night: a pilot randomized controlled trial.
Psychopharmacology, 241(9), 1815-1825
Citation
Suraev, Anastasia; McCartney, Danielle; Marshall, Nathaniel S; Irwin, Christopher; Vandrey, Ryan; Grunstein, Ronald R; D'Rozario, Angela L; Gordon, Christopher; Bartlett, Delwyn; Hoyos, Camilla M; McGregor, Iain S. (2024). Evaluating possible 'next day' impairment in insomnia patients administered an oral medicinal cannabis product by night: a pilot randomized controlled trial.. Psychopharmacology, 241(9), 1815-1825. https://doi.org/10.1007/s00213-024-06595-9
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