File photo: Rachael confesses she now regularly uses alcohol three or four times a week to get her off to sleep. Picture: Reuters

Why are so many mothers drinking themselves to sleep? Once it would have been a bedtime mug of cocoa. Now it's glasses of wine...

For seven, long, fretful nights, sleep had eluded Rachael Short. On the eighth, she could take no more — so she crept downstairs in the middle of the night and poured herself a drink. Not just a soothing nip of brandy either, but a whole pint of wine. Then she downed the lot.

"It was drastic and a bit irresponsible but I was utterly exhausted and at my wit’s end," says Rachael, 33, who is single and lives in Lincolnshire with her son and daughter, aged five and three.

"And it did the job. I’d tried all the traditional sleep remedies — herbal tablets, relaxation apps, breathing techniques — but nothing worked. With the wine, I fell asleep almost immediately and slept peacefully until morning." And apart from a slight headache the next day, and the odd stab of guilt, Rachael was none the worse for her night-time binge.

And although that whole pint of wine was most definitely a one-off — the desperate act of a desperate woman — Rachael confesses she now regularly uses alcohol three or four times a week to get her off to sleep.

A glass or two of wine at bedtime has become her "cocoa", she says, and it never fails.

Rachael, a full-time mother, certainly isn’t alone in her booze-to-snooze tactics. She represents a group of women who go beyond the so-called "wine o’clockers" — those who traditionally uncork a bottle to take the edge off a fraught day once the children are finally in bed.

Indeed, a substantial number of women like Rachael won’t touch a drop until bedtime, when they use it as a calculated sleep strategy. A study by The Sleep Council revealed that 25 percent of us now regularly rely on alcohol as a "sleep remedy", compared with 16 percent in 2013.

According to Professor Kevin Morgan at Loughborough University Sleep Research Centre, the frazzled middle classes are the main culprits.

"Many people turn to alcohol to help them sleep, and certainly it has a direct impact on sleep," he says.

"But we’re not talking about binge- drinking students. This is about the middle classes drinking regularly at home — every night in many cases; and women consuming way above the recommended 14 units per week, specifically to help them unwind enough to fall asleep."

Like millions of mothers, lack of sleep has plagued Rachael since having children: Jacob, who’s five, barely slept until he was three.

"It’s as though not sleeping has become a habit for me — made worse by the normal worries that come with motherhood and keep my mind whirring," she says.

A bottle of red, white or rose contains around four big glasses. Each glass equates to 2.4 units of alcohol, which, even if only one glass is consumed each night, is going to put the drinker over the limit of 14 units a week.

As well as the well-publicised health risks associated with habitually drinking more than recommended levels, too much alcohol will also exacerbate sleeplessness.

"Just like lack of sleep itself, the use of alcohol to get to sleep has been with us since time immemorial," says Professor Horne. "But it’s about moderation. A nightcap, such as a glass of warm milk with a shot of brandy, can help you to settle.

"But drinking too much will have an adverse effect. It might knock you out, but alcohol tends to be metabolised fairly quickly. So after about four hours your blood alcohol levels will have plummeted and this tends to cause you to wake during the night in a state of agitation.

"Also, too much alcohol can lead to snoring, because the muscles at the back of the throat relax, and results in disturbed sleep."

So just how much sleep does the average woman actually need?

Professor Horne says: "The acid test of insufficient sleep is simple. We all have a bit of an early afternoon dip, but if you’re sleepy throughout the day, you’re not getting enough."