Excess alcohol or alcohol used to promote sleep, however, tends to fragment sleep and cause wakefulness a few hours later. It also increases the risk for other sleep disorders, including sleep apnea and restless legs. Alcoholics often suffer insomnia during withdrawal and, in some cases, for several years during recovery.
A number of studies have reported that shift work throws off the body’s circadian rhythm and have suggested that such changes could lead to chronic insomnia. One study found that 53% of night-shift workers fall asleep on the job at least once a week, implying that their internal clocks do not adjust to unusual work times.
They are also at much higher risk than other workers for automobile accidents due to their drowsiness and may also have a higher risk for health problems in general. A Japanese study reporting on different aspects of insomnia found that excessive computer work was associated with all forms of insomnia. People who were over-involved with their work tended to have trouble falling asleep and they tended to awaken earlier than average.