a characteristic withdrawal syndrome that develops after cessation of (or reduction in) prolonged, heavy nicotine consumption. Two or more of the following are required for a DSM–IV–TR diagnosis of nicotine withdrawal: dysphoria or depressed mood; insomnia; irritability, frustration, or anger; anxiety; difficulty in concentrating; restlessness; decreased heart rate; and increased appetite or weight gain. The equivalent term in DSM–5 is tobacco withdrawal.