Nicotine changes the levels of certain brain chemicals -- particularly dopamine, which is famous for making you feel good and dulling pain.
Because the nicotine in one cigarette doesn't stay around forever, you get the urge for another cigarette. However, your brain starts to adjust to those extra surges of dopamine. Soon, what used to feel like a high dopamine level feels normal to you. If the nicotine supply is abruptly cut off, your dopamine plummets.
Your body rewards nicotine consumption by bringing your blood pressure and pulse rate back to normal. In other ways, it protests lack of nicotine consumption. The jittery irritability that makes you crave another cigarette is a withdrawal symptom. Refrain from smoking for 8 hours or so and more withdrawal symptoms present themselves. Some, like dizziness, last only a few days; a few, like fatigue, last several weeks.
One reason that nicotine is addictive is that it creates pleasure in the brain, causing a feeling of relaxation. Over time, nicotine keeps your brain from supplying these chemicals that create these good feelings, and you end up craving more nicotine and the feeling it produces. An alcohol addiction works in the same way but with added disadvantages. Excessive alcohol can lead to other mental disorders, such as anxiety and depression.
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YOU: The Owner's Manual, Updated and Expanded Edition: An Insider's Guide to the Body that Will Make You Healthier and Younger
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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.