When you smoke a cigarette, natural chemicals in your body, called endorphins, immediately signal your brain to make you think you feel better. Nicotine addiction alters the normal endorphin cycle in your body so you have a hard time feeling good without the use of nicotine, whether it is from cigarettes, dip, chew, cigars or pipes. As you know, the effects of nicotine wear off quickly (usually 1 to 2 hours).
As time goes by, endorphin levels in your body drop far below normal, and you begin to feel extremely irritable, upset, stressed, fatigued, and anxious for another cigarette. After you inhale again, endorphin levels are raised back up to a point where you feel better. This continues on and on and on in a never ending cycle. This is your nicotine addiction and this is why it is difficult to quit smoking or dipping.