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Sleep Problems Associated with Alcohol

Posted in Alcoholism

Many people experience sleepiness associated with alcohol consumption. A few glasses of wine at a party can cause some to head home and hang up their party shoes in exchange for slippers and some sleep.

A recent story, however, provides evidence that far from helping people catch up on sleep, alcohol consumption actually leads to an interference with the restorative functions of sleep. The study, to be published in the November 2011 issue of Alcoholism: Clinical & Experimental Research, measured the acute effects of alcohol on the relationship between sleep and heart rate variability (HRV).

Alcohol is known to cause problems with sleep latency, slow-wave sleep and suppress rapid eye movement during the first half of sleep. The second half of sleep has an increase of REM and sleep is shallower.

How the Nervous System Is Impacted by Alcohol

Yohei Sagawa is a medical doctor in the Neuropsychiatry Department at the Akita University School of Medicine. Sagawa explains that alcohol can impact the nervous system during sleep. When people are sleeping, the parasympathetic nervous system, which presides over restful activities, is dominant over the sympathetic nervous system, which presides over more stimulating activities.

The study is unique because it is the first to examine not only alcohol’s effects on sleep, but its effects on the specific roles within the nervous system.

Sagawa and colleagues recruited 10 male university studies with a mean age of 21.6. The students were given one of three different alcoholic beverages every three weeks. Each student was monitored using a Holter electrocardiogram for 24 hours. The students were to consume one of the three alcoholic beverages 100 minutes before going to bed.

The researchers conducted polysomnography on the subjects for eight hours. Power spectral analysis of the HRV was conducted using the maximum entropy method. The researchers also measured low- and high-frequency components along with their ratios.

Alcohol Interrupts Late Phases of Sleep

While the analysis showed that the first half of sleep after alcohol was satisfactory, the EEG showed that an analysis of the autonomic nerve system indicates that alcohol consumption leads to insomnia rather than good sleep.

Further, as alcohol consumption increased, the heart rate also increased, and the frequency ratio measuring the balance between the sympathetic and parasympathetic systems increased. This indicates that alcohol suppresses the high-frequency component of HRV that measures parasympathetic nerve activity during sleep.

The study found that there are definite negative health consequences to consuming alcohol. If a person habitually drinks alcohol, negative health consequences may be much worse than those observed in the study, which measured the effects of one alcoholic drink.