What does myrcene do in cannabis?

Myrcene is the most abundant terpene in most cannabis strains, typically comprising 20–65% of the terpene profile. It is also found in hops, mango, and lemongrass. Myrcene is widely claimed to produce sedative "couch-lock" effects and to enhance THC's psychoactivity by increasing blood-brain barrier permeability — but the evidence for both claims is weak. The sedative effects of myrcene in animal studies require doses far higher than those present in cannabis. The blood-brain barrier claim originates from a single 1997 study that has not been replicated. Myrcene does show analgesic and anti-inflammatory properties in preclinical models, acting via opioid receptors and TRPV1 channels. It is also a muscle relaxant in animal models. The popular claim that eating mango before cannabis enhances the high due to myrcene is not supported by pharmacokinetic evidence.