No Morning After Effects: Study Finds Cannabis Use Before Bed Doesn’t Impact Cognitive Ability or Driving

A new study suggests that using marijuana before sleep has minimal, if any, effect on a range of performance measures the next day, including simulated driving, cognitive and psychomotor function tasks, subjective effects, and mood.

Research Overview

The report, conducted by researchers from several institutions including Macquarie University in Sydney and Johns Hopkins University, analyzed data from a larger study focused on the effects of THC and CBD on insomnia. It specifically looked at outcomes from 20 adults diagnosed with insomnia who infrequently used marijuana.

Lack of Next-Day Impairment

According to the study, a single oral dose of 10 mg THC (combined with 200 mg CBD) did not notably impair next-day cognitive function or driving performance in adults with insomnia who infrequently used marijuana. The researchers observed no significant differences in next-day performance in 27 out of 28 cognitive and psychomotor function tests and simulated driving tests compared to a placebo.

Study Design and Results

Participants were randomly given either a placebo or a cannabis oil containing 10 mg THC and 200 mg CBD. Cognitive tests were administered within two hours of waking, and driving performance was measured using a fixed-base driving simulator 10 hours after administration. Overall, the study found no significant differences between the THC–CBD group and the placebo group in cognitive performance or driving abilities.

Comparison with Other Substances

The study compared the effects of THC and CBD with commonly prescribed sedative-hypnotics like benzodiazepine and zopiclone, noting that these substances are known to impair next-day function. In contrast, cannabis use did not show impairments in driving performance or cognitive function the following day.

Study Limitations and Future Research

The researchers acknowledged the study’s small sample size and the fact that it only examined a single dose of cannabis oil. Further research is needed to explore the effects of repeated dosing with THC and CBD on daytime function in individuals with insomnia.

While some cannabis users may report residual effects the day after use, this study suggests that using marijuana before sleep does not significantly impair next-day performance in adults with insomnia who infrequently use marijuana. The findings contribute to a growing body of research on the potential effects of cannabis on sleep and daytime functioning.