Nicotine

Withdrawal symptoms

If you abruptly stop smoking, nicotine is no longer present in the brain. The insensitivity caused by the nicotine diminishes, and acetylcholine can activate the acetylcholine receptors normally again.

However, far more receptors now exist than before you started smoking, so these relay far more messages. The neurons are bombarded with stimuli and become highly activated. This leads to withdrawal symptoms like jitteriness, irritability, anxiety, insomnia, depression and poor concentration.