Australian Researchers Dive Deeper Into Sleep/Alcohol Research

Though it has been well-established that alcohol consumed too close to bedtime will have a disruptive effect on sleep quality, little research has been done into exactly what the mechanism is that causes this disruption. But now a team of researchers from the University of Melbourne in Australia has determined that drinking alcohol creates a specific and unusual pattern of brain wave activity, and it is to this that the disruption can be attributed.

According to Christian L. Nicholas, corresponding author for the study and the National Health & Medical Research Council Peter Doherty Research Fellow in the Sleep Research Laboratory at The University of Melbourne, pre-sleep drinking’s initial sedative effect is initially seen as an increased period of slow wave sleep, but then shows significant increases in frontal alpha power, a condition that is known to be a reflection of disturbed sleep. “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. 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,” he says. He goes on to say, “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.”

To accomplish their research, Nicholas and his colleagues performed polysomnography tests with comprehensive EEG recordings on a group of two dozen health 18-21-year-old volunteers, half male and half female. The group was qualified by having consumed less than seven alcoholic drinks per week over the previous month. The group was provided with pre-sleep alcohol or a placebo before undergoing the test.

The study showed that consuming alcohol before bedtime increased short wave sleep during non-REM sleep, but at the same time front alpha power increased. “For individuals researching sleep in the field of alcohol studies,” Nicholas said, “our findings indicate that care needs to be taken when interpreting increases in ‘visually scored’ short wave sleep (SWS) associated with alcohol consumption. Increases in SWS, which traditionally would be interpreted as a good thing, can be associated with more subtle changes indicating disrupted sleep, such as the increases we observed in alpha activity, which are revealed when more detailed micro-structural components of the sleep electroencephalogram are assessed.”

The group believes that the increase in frontal alpha power that results from the pre-sleep drinking is a reflection of a disruption of what normally goes on in the brain during non-REM 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. Thus, if sleep is being disrupted regularly by pre-sleep alcohol consumption, particularly over long periods of time, this could have significant detrimental effects on daytime well-being and neurocognitive function such as learning and memory processes.” He adds, “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.”