London: Taking alcohol before bedtime has long been viewed by many as one of the ways to sleep. But a new study has found that alcohol in fact causes insomnia and deprives a night`s rest of its restorative powers.
For the study, students were given a series of alcoholic drinks of varying strengths an hour and 40 minutes before going to bed. Each time readings were taken that recorded activity in their heart and brain, Daily Express reported.
Researchers found that alcohol resulted in sleeplessness and the disturbed nights left the students exhausted.
The alcohol suppressed parasympathetic nerve activity - the part of the "autonomic", or non-voluntary, nervous system that slows heart rate and aids digestion, it was found.
The findings were published Tuesday in the journal Alcoholism: Clinical & Experimental Research.
Study leader Yohei Sagawa, of Akita University, Japan, said: "Although the first half of sleep after alcohol looks good, drinking leads to insomnia rather than good sleep."
Sagawa`s US colleague Seiji Nishino said: "It is generally believed a nightcap may aid sleep, especially sleep initiation.
"This may be true for some who have small amounts of alcohol. However, large amounts interfere with sleep quality and the restorative role of sleep.
"These negative consequences may be much larger during chronic alcohol intake."