"A psychoactive dose of THC increases internal clock speed as indicated by time overestimation and underproduction. This effect is not dose-related, and is blunted in chronic cannabis smokers, who did not otherwise have altered baseline time perception."<p>This is consistent with simply being dropped in an unfamiliar environment and slowly adapting to it. We call them "trips" for a reason. A new drug is a foreign country. For pot a chronic stoner is a local. You could get similar overestimation and underproduction by jetting them to a place full of strange people, languages and customs.