The effect of low-dose cannabinol on sleep in rats

As the use of cannabinol, often marketed as a sleep aid, is increasing, we aimed to investigate the effect of this substance on sleep. We evaluated the effect of a low dose (1 mg/kg) of cannabinol in rats using electrocorticography and electromyography. Three groups were compared: rats that received saline, vehicle (1% Tween-80 dissolved in saline), and cannabinol dissolved in vehicle. We recorded data for 24 hours after a single injection, and for 7 days with injections taking place every day. Cannabinol decreased the percentage of time spent in non-REM sleep at different times across the day, compared to both vehicle and saline. Importantly, Tween-80 decreased REM sleep when compared to saline. Most differences emerged in day 2 of continuous substance administration, with effects decreasing towards the end of the week. Caution should be taken when using cannabinol as a sleep aid, as our results suggest no somnogenic effect. The effect could depend on dose, and more research is needed. Furthermore, Tween-80, a common solvent in pharmacological studies, has an effect on REM sleep, which needs to be taken into account when planning and performing such research.