Cravings: Nicotine attaches strongly to receptors in the brain, and that leads to an incredibly powerful addiction, says Renee Fogelberg, MD, clinical lead for the Tobacco Cessation program for Kaiser Permanente in Northern California. These changes to your brain chemistry cause you to continue craving a smoke.
Irritability and trouble concentrating: Nicotine makes you feel good — that’s why you smoke — so when you don’t have it anymore, it’s common to feel irritable and fatigued, Dr. Fogelberg says. Nicotine also affects your thinking, so people who’ve quit may experience trouble concentrating, memory issues, and not thinking as quickly, Dr. Spangler says.
Anxiety or depression: Not getting the powerful hit nicotine delivers to your brain can affect your mood, according to Amanda L. Graham, PhD, director of research development at the Schroeder Institute for Tobacco Research and Policy Studies in Washington, D.C. Some people may feel anxious, while others may feel depressed.
Trouble sleeping: Nicotine affects neurotransmitters that regulate sleep. A study published in Addiction Biology in July 2015 found that smokers who quit experienced more arousal and trouble sleeping in the 24 to 36 hours after quitting.