Persons consuming alcohol before sleep are found to have sleep disturbances later, found in a study, increasing the SWS-related delta power and frontal alpha power.
Significant reductions in EEG delta frequency activity and power also occur with normal development between the ages of 12 and 16; likewise this is a time when alcohol is commonly consumed for the first time, with dramatic increases in drinking occurring among college-age individuals. A study of the effects of alcohol on sleep EEG power spectra in college students has found that pre-sleep drinking not only causes an initial increase in SWS-related delta power but also causes an increase in frontal alpha power, which is thought to reflect disturbed sleep.
Christian L. Nicholas, corresponding author for the study, said that people likely tend to focus on the commonly reported sedative properties of alcohol, which is reflected in shorter times to fall asleep, particularly in adults, rather than the sleep disruption that occurs later in the night.
Nicholas and his colleagues recruited 24 participants (12 female, 12 male), healthy 18- to 21-year-old social drinkers who had consumed less than seven standard drinks per week during the previous 30 days. Each participant underwent two conditions: pre-sleep alcohol as well as a placebo, followed by standard polysomnography with comprehensive EEG recordings.
Results showed that alcohol increased SWS delta power during NREM. However, there was a simultaneous increase in frontal alpha power.
Nicholas explained that the increase in frontal alpha power that occurs as a result of pre-sleep drinking likely reflects a disruption of the normal properties of NREM slow wave sleep.
Similar increases in alpha-delta activity, which are associated with poor or unrefreshing sleep and daytime function, have been observed in individuals with chronic pain conditions, he added. Thus, if sleep was being disrupted regularly by pre-sleep alcohol consumption, particularly over long periods of time, it could have significant detrimental effects on daytime well-being and neurocognitive function such as learning and memory processes.
Results will be published in the online-only issue of Alcoholism: Clinical and Experimental Research and are currently available at Early View.