Delta-9-tetrahydrocannabinol (thc) ingestion before bedtime reduces nocturnal parasympathetic control of the heart

Abstract Introduction The use of cannabis as a sleep aid has increased despite inadequate evidence of its efficacy or associated risks. Delta-9-tetrahydrocannabinol (THC) is the primary psychoactive constituent of cannabis. Acute THC administration can induce CB1R mediated reductions in total peripheral resistance resulting in dose-dependent increases in heart rate and reductions in heart rate variability (HRV) in awake subjects. However, the influence of THC on vagal-cardiac modulation during sleep is unclear. Methods 7 individuals who use cannabis (>3x/week for 3 months; CUDIT-R = 8±1) and 8 cannabis-naïve participants (combined: age range 21-32 years; 9 female) were recruited to participate in this repeated measure, single blinded, placebo-controlled study. One hour before habitual sleep, participants received either a placebo pill or 10mg of THC. Polysomnography (PSG) and ECG were recorded over these 2 nights. HRV was assessed in both time and frequency domains in 2-min epochs of stable N2, N3 and REM sleep. Repeated measures ANOVA comparisons were made for PSG and HRV variables. [(*)=p< 0.05] Results There were no significant changes in total sleep duration or sleep architecture (N2%, N3%, & REM%) between the placebo and dosing night in either group. Compared to the placebo night, both individuals who use cannabis and cannabis naïve participants exhibited significant decreases in HRV variables throughout the night when dosed with THC. R-R interval decreased by 25±10* ms [mean±SE] (2%) in the naïve group and 62±11* ms (6%) in the cannabis group. RMSSD decreased by 15±3* ms (22%) in the naïve group and 11±3* ms (23%) in the cannabis group. PNN50 decreased by 9±3* % in the naïve group and 11±3* % in the cannabis group. In naïve participants high frequency spectral power decreased by 398±76* ms^2 (32%). Conclusion Our results suggest that THC ingestion before bedtime did not systematically affect sleep depth or duration, but did significantly reduce vagal-cardiac modulation in individuals who use cannabis as well as in cannabis naïve participants. Acute reductions in parasympathetic control of the heart may indicate increased cardiovascular stress during sleep when THC is ingested. Support (if any) AASM; K01HL151745; T32HL083808; OHSU OFDIR; R35 HL155681; Oregon Institute of Occupational Health Sciences