 A fresh quid may be prepared and held in the mouth while sleeping, so that for some chewers nicotine absorption is constant.At first, nicotine acts as a stimulant, boosting the production or availability of chemicals such as acetylcholine, norepinephrine, dopamine, beta-endorphin and serotonin in the brain and other parts of the body.After sustained use, though, the body's ability to maintain heightened levels of these chemicals is temporarily exhausted and nicotine begins to act as a depressant and in high doses may induce stupor or trance.