Bedtime THC may leave new users dizzy the next morning

Acute cannabis use and its primary psychoactive constituent tetrahydrocannabinol (THC) can induce postural dizziness, indicating increased risk of orthostatic instability. However, it is unknown if vulnerabilities persist the morning after bedtime THC consumption. This study investigated the influence of bedtime THC consumption on cardiovascular variables during an orthostatic challenge. Nine individuals with no cannabis use and eight individuals who regularly use cannabis participated in a tilt table test associated with a 3-day in-laboratory stay. Participants underwent an acclimatization day, followed by a placebo dosing day, and a 10 mg THC dosing day. Placebo and THC pills were given 1 h before a participant's habitual bedtime, and the tilt table test was performed ~1 h upon awakening. Participants were instrumented with an electrocardiogram and an automated sphygmomanometer. Fluid intake and output were measured throughout the study. The morning after THC administration, individuals with no cannabis use reported a higher frequency of dizziness and exhibited a significant reduction in both diastolic blood pressure and heart rate reactivity to tilt (reactivity = tilt - baseline) compared to the morning after placebo. Our results indicate a potential increased risk for orthostatic instability the morning after cannabis consumption in individuals with no cannabis use history.