Small amount of drink disrupts sleep, study finds

If you have ever felt tired the morning after the night before, you might be relieved to learn that even a small amount of alcohol disrupts your sleep.

New Irish research claims to be the first study to show that even low levels of alcohol consumption cut time asleep.

The research, published in international journal Alcohol and Alcoholism, said small amounts of drink “significantly” reduce the total time spent asleep and induce “waking fatigue”.

It said waking fatigue was known to pose potentially serious consequences in relation to accidents, including on the road.

The researchers, from University College Hospital Galway and Trinity College Dublin, said alcohol was probably the most frequently used sleeping aid in the general population, based on its effects on inducing sleep.

The research team selected 47 college students and attached actigraphs on their wrists, which monitors the amount, duration and intensity of movement. In addition, students were given a sleep diary to record certain information.

Of the 33 students who drank, the average amount consumed per night was 8.5 British units, roughly equivalent to between three and four pints of beer or three large glasses of wine.

Some 18 consumed a low amount, 4.9 units, equivalent to between one and a half and two and a half pints of beer or a glass and half of wine.

Some 15 consumed high doses, of 12.7 units, equivalent to between four and six pints of beer or four large glasses of wine.

“Mean total sleep for the group as a whole was significantly reduced on alcohol,” said the report.

“This reduction was observed in both low and high-dose groups, though the decrease was smaller in the high-dose group.”

The report said the effects were particularly large on the those in the low-dose group, who lost 47 minutes each.

The reduction in sleep time was associated with increased wakefulness in the second half of the night, a truncated sleeping period and increased waking fatigue.

“The finding that total sleep time is reduced on low doses is novel,” said the report. It said this may be due to the fact they measured sleep in a normal environment, in people’s homes, rather than laboratories, as in previous studies.

The report said studies have documented the risks posed by fatigue and sleepiness in the day after drinking.

The research was carried out by Pierce Geoghegan, Mairead O’Donovan and Brian Lawlor and made publicly available by the Health Research Board.

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