Alcohol linked to insomnia

AKITA CITY, Japan, Aug. 15 (UPI) -- A study of alcohol, sleep and heart rate variability found that alcohol interferes with the restorative functions of sleep, Japanese and U.S. researchers say.

"Alcohol affects overall sleep architecture," Dr. Yohei Sagawa of Akita University School of Medicine in Japan says. "Normally, during physiologic nocturnal sleep in humans, the parasympathetic nervous system, responsible for 'rest-and-digest' activities, is dominant over the sympathetic nervous system, responsible for stimulating activities. We wanted to investigate how alcohol may change this complementary relationship."

Sagawa and colleagues gave 10 healthy, male university students with a mean age of 21.6 years three different alcohol beverages at three week intervals -- 0 alcohol (control), a low dose of alcohol, or a high dose of pure ethanol/2.2 pounds of body weight.

A Holter electrocardiogram was attached to each subject for a 24-hour period and the subject was instructed to drink one of the three alcoholic beverages 100 minutes before going to bed. Polysomnography -- recording of the biophysiological changes that occur during sleep -- was then performed for 8 hours.

"Although the first half of sleep after alcohol intake looks good on the electroencephalogram, the result of the assessment regarding the autonomic nerve system shows that drinking leads to insomnia rather than good sleep."

The findings are published online ahead of the November print issue of Alcoholism: Clinical & Experimental Research.