Effects of alcohol, caffeine, and cannabidiol on sleep

Alcohol and caffeine are widely used legal drugs across the world which are principally used in social and recreational contexts. There is a large literature that has documented the effects of alcohol and caffeine on sleep and daytime alertness. While at low doses they initially improve sleep (alcohol) or daytime alertness (caffeine), ultimately they both disrupt either the initiation, maintenance, or staging of sleep and diminish daytime alertness. Cannabidiol is one of the two most biologically active compounds of the cannabis plant. It's use has increased over the last five years and is primarily used for its medicinal effects, among them insomnia. While now legal (2018) in the US, it falls under varying governmental controls in other countries across the world. The literature on the effect of cannabidiol on sleep, either beneficial or disruptive, is very limited. Further clarification of the risks versus benefits of these three widely used substances will improve our understanding of their effects on sleep and daytime alertness and strengthen public health guidance and messaging.