Terpenes work together with cannabinoids, in a process known as the entourage effect. Terpenes can also modify how much of each cannabinoid is absorbed. This means the presence of certain terpenes can increase or decrease the amount of the psychoactive cannabinoid THC is absorbed, effectively controlling the potency. Different terpenes may help to induce sleep and relax muscles while others reduce stress and elevate mood, or reduce inflammation and increase energy.