(posted August 21, 2006)
While numerous studies have linked alcohol abuse to sleep disruption, especially in males, there has been little research on alcohol and its effects on sleep in females. Now, a new study shows that a moderate amount of alcohol, taken before bed, can impact the quality of sleep for young women.
"We found that a moderate dose of alcohol consumed by a young woman an hour before bed is associated with increased sleep intensity in the first couple hours of the sleep episode," says author Mary Carskadon, PhD, a researcher with the Bradley Hospital Sleep and Chronobiology Laboratory and Brown Medical School.
This phenomenon was observed in well-slept women using an alcohol dose of 0.49 g/kg, equivalent to two to three standard drinks (in the form of vodka tonics), in the hour before bedtime, or 0.5 g/% below the legal limit for driving while intoxicated in many states.
Appearing in the June 2006 issue of the journal Alcoholism: Clinical and Experimental Research, this study looked at the sleep habits of young women (between ages 22 to 25) who drank alcohol before bed, over the course of three nights. Researchers monitored the women's sleep and sleep electroencephalograms (EEGs), a graphic record of the electrical activity of the brain-a technique that can analyze the "microarchitecture" of sleep.
Researchers found few, but noteworthy differences between sleep and sleep EEG with alcohol versus placebo. When alcohol had been consumed, rapid eye movement (REM) sleep decreased, while stage 4 sleep (the deep sleep early in the night) was slightly increased. In addition, spectral analysis of the EEG showed signs of increased sleep intensity during non-REM (NREM) sleep after alcohol compared with placebo.
"Whether this sleep pattern is beneficial or harmful is unknown at this point. Although it may signal an initial consolidation of sleep, it might also be associated with difficulty waking in the event of an emergent problem, such as a fire or medical emergency," says author Eliza Van Reen, a psychology graduate student at Brown University.
More work is needed to examine other alcohol doses, sex differences, and vulnerability that may occur with a positive family history of alcoholism, the authors conclude.