We know cannabis use affects sleep. While it has been used for centuries to improve sleep, there is more recent evidence it can also interfere with sleep depending on the amount used. But why?
A published study in the journal Sleep sheds some light on this connection by showing certain shared genes predispose people to both cannabis use and problems with sleep.
Researchers at the Institute for Behavioral Genetics at the University of Colorado, Boulder, looked at the genetic relationship between cannabis use and sleep disturbances—insomnia and getting less than seven hours of sleep—in two steps. First, they measured the genetic correlations between sleep deficits and cannabis use behaviors.
Then, they estimated whether a risk of sleep deficit could predict cannabis use. They mined genetic databases to measure something called a polygenic risk score (PRS) to accurately predict whether an individual had sleep problems. A PRS estimates the extent to which a number of genes work together to affect a particular trait, in this case sleep or cannabis use.
Using statistics to compare the PRS for both sleep and cannabis use, the authors showed that the two traits were genetically linked. They were also able to use PRSs to estimate the age when cannabis use began and the extent of cannabis use over an individual’s lifetime.
While this study offers some insight into the link between cannabis use and sleep, more work needs to be done to understand why the effects of cannabis and individual cannabinoids (e.g., THC and CBD) on sleep depend on the dose.
Low-dose THC and high-dose CBD seem to increase slow-wave sleep and sleep duration, while high-dose THC and low-dose CBD appear to interfere with sleep. Additionally, there is a lot of anecdotal evidence that cannabis can improve sleep disturbances associated with multiple sclerosis, fibromyalgia, IBD, and chronic neuropathic pain.
Further studies will also need to expand the study population as this study was limited to a genetic analysis of mostly white people of European ancestry.