How smoking affects the brain
Within 10 seconds of inhaling tobacco smoke, nicotine reaches the brain and begins to act on a specific set of neurons, the working cells of the brain. On each of these neurons are receptors, which are like slots or keyholes onto which brain chemicals called neurotransmitters attach, causing the brain to transmit messages. Nicotine fits into one of the receptors acted upon by acetylcholine, one of several neurotransmitters in the brain. This causes the brain to release two other substances, noradrenaline and dopamine, that act as stimulants. [i]
Smoking and Stress
Smokers often report that smoking tobacco helps to relieve feelings of anxiety and stress. However, smokers exhibit higher levels of stress in their lives than non-smokers. The high smoking prevalence among people facing social and economic deprivation suggests that smoking may be used as a stress coping mechanism.[ii] However, the stress reducing properties of nicotine seem more illusory than real.
Nicotine stimulates the brain to release dopamine, which is associated with pleasurable feelings, and smokers quickly develop regular smoking patterns. Eventually, smokers need increasing levels of nicotine to feel ‘normal’. As the nicotine content in their blood drops below a certain level, they begin to crave for a cigarette. This craving makes the smoker feel ‘stressed’ until the craving is relieved. The relief felt when this craving is finally satisfied is the feeling that smokers commonly mistake as ‘relaxing’. (see also fact sheet no 9, Nicotine and Addiction)
Resumiendo: la nicotina no reduce el estrés, lo que reduce es la ansiedad producida por la falta de nicotina. Por condicionamiento el tabaco se asocia por sus contingencias al relax, por eso se asocia el tabaco con la reducción del estrés. Hay estudios que incluso asocian el tabaquismo con mayores índices de depresión y ansiedad, muchos expertos consideran que dejando el tabaco se reduce ese "estrés" relacionado con el tabaquismo.