Return to Smoking & Vaping Lack of Focus Chest Tightness Cold Symptoms Cravings Dizziness Gas Hunger Irritability Lack of Focus Low Energy Sleepiness Ways to Cope Why you’re feeling itYour brain is used to getting a buzz (stimulation) from nicotine. Now it’s learning to stay alert without nicotine. How long it lastsA few weeks What you can doIf you can, work a little less. Take lots of breaks.