It may help you nod off but the sleep you get after drinking alcohol is not a good one, according to new research.
US and Japanese researchers have shown that even a small amount of alcohol before bed can interfere with the restorative sleep phase, when your body does it’s recovering from the previous day.
During normal sleep the body’s parasympathetic nervous system, which is responsible for ‘resting and digesting’, takes over from the sympathetic nervous system which regulates the body’s response to daily events or stimulants.
But the researchers found that alcohol interfered with that phase of sleep. Instead of seeing an expected lowering of heart rate and shallower breathing, they noted that the subjects in their study had higher heart rates.
In a sneak peak of their yet to be published study, the authors said that even a single dose of alcohol interfered with sleep patterns, leading to insomnia and other negative health effects.
The researchers gave 10 healthy male university students three different alcohol beverages at three week intervals: 0g (control), 0.5g (low dose), or 1.0g (high dose) of pure ethanol/kg of body weight.
On the day of the experiment they wore a portable ECG machine which measured their heart rate for a 24 hour period. They were instructed to drink their drinks 100 minutes before going to bed. A sleep analysis was performed for eight hours overnight.
"Although the first half of sleep after alcohol intake looks good on the EEG, the result of the assessment regarding the autonomic nerve system (both parasympathetic and sympathetic nervous systems) shows that drinking leads to insomnia rather than good sleep," the researchers said.
The authors noted this was only a single dose of alcohol and speculated on the effects of results if more alcohol were consumed. With many people habitually drinking alcohol “the negative health consequences may be much larger and include various diseases” such as hypertension.
"Many alcoholics and habitual drinkers suffer from insomnia," they said. Insomnia includes difficultly getting to sleep, early-morning awakening, lack of a sense of deep sleep, and difficulty maintaining sleep.
"It is generally believed that having a nightcap may aid sleep, especially sleep initiation," they said, but alcohol intake can interfere with sleep quality and the restorative role of sleep.
The results will be published in the November 2011 issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View. The paper is called "Alcohol Has a Dose-Related Effect on Parasympathetic Nerve Activity During Sleep."