The World Health Organization reports that, unlike THC, CBD—the second most well-known active ingredient in cannabis—does not produce a high and seems to result in less REM-sleep (that deep, restorative sleep) disruption than THC. In short, CBD may help a person fall and stay asleep by calming the nervous system. CBD is known to have antipsychotic effects, but that the cause for these effects remains unknown, or at the very least, unproven. Experts believe that CBD may prevent the breakdown of a chemical neurotransmitter in the brain that affects mental function, emotional state and pain, thus allowing for more of the sleep-promoting chemical to flow through the bloodstream and cause drowsiness.