Sleep problems, which can have significant clinical and economic consequences, are more common among alcoholics than among nonalcoholics. During both drinking periods and withdrawal, alcoholics commonly experience problems falling asleep and decreased total sleep time. Other measures of sleep are also disturbed. Even alcoholics who have been abstinent for short periods of time (i.e., several weeks) or extended periods of time (i.e., several years) may experience persistent sleep abnormalities. Researchers also found that alcoholics are more likely to suffer from certain sleep disorders, such as sleep apnea. Conversely, sleep problems may predispose some people to developing alcohol problems. Furthermore, sleep problems may increase the risk of relapse among abstinent alcoholics.