Many people know the theory that people who smoke a lot develop a ‘tolerance’ for THC. This is not a myth. Recent studies are indicating that the physiological effect of THC is indeed lessened upon regular exposure. Cognitive function was the area that showed the most tolerance, with some evidence of full tolerance. And the general intoxicating effects of THC are also shown to be blunted to a lesser extent.
The endocannabinoid system has a certain number of these CB1 receptors that during normal body function will stimulate the brain at the ‘desired level’. When THC floods your system and all of the CB1 receptors are activated your brain will become overstimulated (read high). Your brain’s number one role is to regulate your body chemistry, so if high concentrations of THC are sustained over time the body will decrease the number of CB1 receptors (up to 48%) to regulate the sensory load on the brain.
This is a completely reversible process as when you take a break from THC for a while (3-12 days based on mice studies) then the body will bring back these CB1 receptors.