Smoking fosters a situation of nicotine dependence that usually occurs over a number of years. Withdrawal symptoms can include headaches, irritability, anxiety, fatigue, depression and weight gain. Nearly everybody experiences at least some of these symptoms but they are mostly temporary.
Smoking creates a chemical dependency for nicotine. Nicotine can act either as a stimulant or a sedative, depending on the amount taken. The smoker’s body finds an acceptable level of nicotine in order to experience the pleasurable sensations associated with smoking. Nicotine increases the release of dopamine which is the chemical that causes the sensation of pleasure. The first cigarette of the day is usually most effective at stimulating the dopamine receptors in the brain, this is why smokers often find the first cigarette of the day most satisfying. As the day goes on the nerve receptors become desensitised to the effect of nicotine. In fact over time the smoker becomes desensitised and higher levels of nicotine are required to achieve the pleasure sensations.
The body and the nervous system adjusts to constantly receiving this expected level of nicotine and this is what withdrawal symptoms are all about. The more nicotine you have learned to tolerate in your blood, the more likely you are to miss it when you stop