My husband has chronic PTSD related insomnia. Since he’s been prescribed cannabis, he’s been able to actually sleep better than with any of the harsh meds he’s been prescribed in the past.
Caveat: He was told it can interfere with REM, which in his case is good since it also helps with the nightmares, but it’s probably not good for regular use by the average person, or so we’ve been told by his provider. Ask your doctor, I guess.