Capping the night off with a glass of wine or a bottle of beer causes sleep disruption leading to poor daytime functioning. Research revealed that although alcohol initially acts as a sedative, it subsequently triggers frontal alpha activity, which is thought to reflect disturbed sleep.
Findings from previous research have described how alcohol can help in inducing sleep. Accordingly, aside from causing muscles to relax, alcohol acts as a depressant when consumed. The hypnotic-sedative effect of alcohol is comparable to the effects of barbiturates and benzodiazepine tranquillisers like Valium, Xanax, and Ativan among others.
However, a new research from Christian L. Nicholas, Julia K. M Chan, John Trinder, and Ian M. Colrain revealed the full-blown effect of alcohol consumption on sleep quality.
The researchers recruited 21 participants composed of healthy 18-21-year-old social drinkers who had consumed less than seven standard drinks per week during the previous 30 days. Each of them was subjected under two conditions involving pre-sleep alcohol and a placebo, followed by standard polysomnography with comprehensive EEG recordings.
As expected, the EEG recordings revealed an increase in Slow Wave Sleep delta power during the NREM. This was an indication of the sedative effects of alcohol. Furthermore, traditional understanding suggests this is an indication of a good sleep quality.
Surprisingly, however, the recordings also revealed an increase in frontal alpha power. According to the researchers, this suggested a disruption of the normal properties of NREM slow wave sleep.
Previous studies have already pinned down the association between an increase in alpha-delta activity and poor sleep quality, which, on the other hand, results in poor daytime function. Moreover, similar alpha-delta activity has been observed in individuals with chronic pain conditions.
“The reduction in delta frequency EEG activity we see across the ages is thought to represent normal brain maturational processes as the adolescent brain continues to develop to full maturity,” said Nicholas. “Although the exact function of non-Rapid Eye Movement (NREM) sleep, and in particular SWS, is a topic of debate, it is thought to reflect sleep need and quality; thus any disruption to this may affect the underlying restorative properties of sleep and be detrimental to daytime functioning.”
If alcohol can cause an increase in alpha-delta activity and thereby, disruption in overall sleep, its regular consumption could have considerable negative effects on daytime function as well as neurocognitive functions including learning and memory processes.
Alcohol is thereby not a sleep aid according to Nicholas. “The take-home message here is that alcohol is not actually a particularly good sleep aid even though it may seem like it helps you get to sleep quicker. In fact, the quality of the sleep you get is significantly altered and disrupted.”
The aforementioned research entitled “The Acute effects of alcohol on sleep electroencephalogram power spectra in late adolescence” appears in the February issue of Alcoholism: Clinical & Experimental Research, the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism.
Lead author Nicholas is a National Health & Medical Research Council Peter Doherty Research Fellow in the Sleep Research Laboratory at The University of Melbourne. Chan and Trinder are from the Melbourne School of Psychological Sciences at The University of Melbourne. Colrain is from the Melbourne School of Psychological Sciences at The University of Melbourne, and the Human Sleep Research Program at SRI International.