No one doubts caffeine can ruin your sleep. But did you know that cigarettes can do the same? Nicotine, like caffeine, is a stimulant after all, and it seems to reduce the quality of sleep in a couple of ways. First, studies show that pack-a-day smokers get less deep delta wave sleep than their nonsmoking friends. We also know that smokers who quit enjoy a sudden surge of delta wave slumber, as if their bodies are trying to catch up.
Smoking also increases congestion in the lungs and nasal passages and causes swelling of the mucous membranes. All that adds up to restricted airflow, which could cause the same kinds of problems found in sleep-apnea sufferers.