• For one in ten Americans who are alcohol dependent, a drink before bed can have a serious effect on their sleep, in most cases creating insomnia rather than eliminating it.
   
• A study conducted by the Addiction Research Center at the U-M Health System showed that up to 75 percent of people who are alcohol dependent experience insomnia.
   
• Drinking before bed can develop into a vicious cycle. When one drink isn't enough to avoid sleeplessness or restless sleep, most often alcohol consumption is increased before bed to aid with sleep.

The average adult sleeps 6.5 to 7 hours every night. Although the function of sleep is unknown, abundant evidence demonstrates that lack of sleep can have serious consequences, including increased risk of depressive disorders, impaired breathing, and heart disease. In addition, excessive daytime sleepiness resulting from sleep disturbance is associated with memory deficits, impaired social and occupational function, and car crashes. Alcohol consumption can induce sleep disorders by disrupting the sequence and duration of sleep states and by altering total sleep time as well as the time required to fall asleep (i.e., sleep latency).

Alcohol consumed at bedtime, after an initial stimulating effect, may decrease the time required to fall asleep. Because of alcohol's sedating effect, many people with insomnia consume alcohol to promote sleep. However, alcohol consumed within an hour of bedtime appears to disrupt the second half of the sleep period. The subject may sleep fitfully during the second half of sleep, awakening from dreams and returning to sleep with difficulty. With continued consumption just before bedtime, alcohol's sleep-inducing effect may decrease, while its disruptive effects continue or increase. This sleep disruption may lead to daytime fatigue and sleepiness. The elderly are at particular risk, because they achieve higher levels of alcohol in the blood and brain than do younger persons after consuming an equivalent dose. Bedtime alcohol consumption among older persons may lead to unsteadiness if walking is attempted during the night, with increased risk of falls and injuries.

Alcoholic beverages are often consumed in the late afternoon (e.g., at "happy hour" or with dinner) without further consumption before bedtime. Studies show that a moderate dose of alcohol consumed as much as 6 hours before bedtime can increase wakefulness during the second half of sleep. By the time this effect occurs, the dose of alcohol consumed earlier has already been eliminated from the body, suggesting a relatively long-lasting change in the body's mechanisms of sleep regulation.

Note: A standard drink is generally considered to be 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of distilled spirits, each drink containing approximately 0.5 ounce of alcohol.

For more information, visit the following Web sites:

U-M Health Topics A - Z: Sleeping Well/Preventing Insomnia
http://www.med.umich.edu/1libr/primry/life16.htm

U-M Health Topics A - Z: What happens when you drink?
http://www.med.umich.edu/1libr/subabuse/alcohl10.htm

U-M Division of Substance Abuse
http://www.med.umich.edu/psych/sub/index.htm

National Institute on Alcohol Abuse and Alcoholism
http://www.niaaa.nih.gov