One of the many useful qualities about marijuana is the mellowing effect; it’s why many people smoke to unwind at the end of a stressful day, and why a growing number of parents choose to smoke a joint over sipping a glass of wine. The sleepiness-inducing virtues of marijuana have made it a popular (albeit questionable) sleep aid, but the leap to helping people coping with PTSD, anxiety, and other mental illnesses remains unsubstantiated.
It is worth nothing that marijuana use before bed increases what’s known as “deep sleep”, a non-dreaming phase of deep sleep in which the person is very difficult to awaken. This comes at the expense of REM sleep, when memories are believed to be solidified and learning occurs—and where dreams happen.1 The increase in deep sleep means that the person feels more rested when they wake up. For PTSD survivors, it makes sense that shortening the dreaming phase would lead to more restful nights. Additionally, because people tend to fall asleep faster it may be useful for coping with an occasional bout of insomnia.
However, in clinical practice the utility of marijuana for mental illness is considerably more limited. There is currently only one longitudinal, triple-blinded randomized study looking at whether marijuana is useful for treating PTSD, and that study is only looking at 76 veterans whose PTSD has been refractory to treatment and therapy.2 There is plenty of evidence for self-medication with marijuana and other drugs for anxiety3 and related conditions, and the ability of marijuana to alter how we deal with fear is well-documented. The danger, though, lies in the blurry line between use and misuse4 that, in the absence of a supportive structure, can initiate a cycle of dependence. But just where this line lies and how to navigate it is something that is not well-understood at all.
But this will be changing soon. In July, the White House5 announced that it would be lifting some of the restrictions for human studies on marijuana, which should result in much more clarity on what marijuana is good for and how it achieves its effects. There is no doubt that marijuana can help people deal with some conditions, but without any concrete guidelines, it is also understandable that doctors will be reluctant to prescribe it for quite a while.
2 MAPS study: http://www.maps.org/marijuana-us