New research shows that cigarette smokers are four times as likely as nonsmokers to report feeling unrested after a night’s sleep. The study, appearing in the February issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians (ACCP), also reveals that smokers spend less time in deep sleep and more time in light sleep than nonsmokers, with the greatest differences in sleep patterns seen in the early stages of sleep. Researchers speculate that the stimulating effects of nicotine could cause smokers to experience nicotine withdrawal each night, which may contribute to disturbances in sleep.