For years we thought that a nightcap would give us a wonderful night's sleep.
However, experts say this logic is flawed.
In fact, they claim that pouring yourself a drink before hitting the bag will only leave you dizzy, dehydrated and possibly with a pounding headache.
Drinking interrupts the REM (Rapid Eye Movement) phase of sleep. This stage – the deepest of four that we all go through every night – is vital for memory, learning and creativity.
Ian Hamilton, who specializes in addiction at the University of York, said this part “provides rest and recovery for the brain.”
Although alcohol decreases consciousness and helps you fall asleep right away, it disrupts REM sleep, causing you to wake up feeling restless.
This is why you can wake up at night after drinking, making you feel less fresh.
Dr. Melissa Oldham, from the Tobacco and Alcohol Research Group at University College London (UCL), explains that this is because the body metabolizes alcohol later in the evening.
After consuming a drink, people may fall asleep more quickly due to the sedative effect of alcohol, which can increase relaxation and drowsiness.
But after alcohol is absorbed from the stomach and small intestine into the bloodstream, it is slowly metabolized overnight.
“This can lead to people waking up more often and feeling more tired the next morning,” she said.
However, it's not just the lack of REM sleep that makes you feel restless; alcohol's dehydrating effects also make you feel tired the next day, experts say.
It can cause drinkers to wake up during the night because they need water and to go to the toilet.
Alcohol can also disrupt sleep by making drinkers sweat more. said Richard Piper of Alcohol Change UK.
He said this worsens dehydration, fatigue and headaches.
Karen Tyrell, CEO of the charity Drinkaware, said: 'It is a diuretic, so if you drink alcohol you may have to get up to go to the toilet during the night, and it has also been found that you can continue to snore. .
'If you drink, try to avoid it close to bedtime and give your body time to process the alcohol you've consumed before going to sleep.'
Regular drinking can cause bouts of insomnia, experts say. In fact, according to the NHS, it is one of the most common causes of the condition, which affects millions of people.
It can take an hour to metabolize one unit of alcohol, meaning alcohol can remain in the blood for a while after someone stops drinking, leading to disturbed sleep
Mr Hamilton said: 'Some people will experience insomnia as a result of regular drinking. Although they may initially fall asleep, they will experience frequent sleep disruptions, leaving them feeling lethargic during the day.”
Eventually, though, the brain gets used to falling asleep with the help of alcohol and starts to expect it, making your sleep even worse, says Mr Piper.
He said: 'If you drink regularly, your brain will have adapted to expect the alcohol before bed and depend on it to get you to sleep.
'But without alcohol in your blood, you sleep more deeply and get that fresh feeling when you wake up in the morning.'
Although it may take a few days to get back to normal sleep as your 'brain unlearns old habits', not drinking will lead to 'deeper, restful sleep', says Mr Piper.
Alcohol Change UK said 70 percent of Dry January participants sleep better.
According to the charity, they also experience increased energy levels, sharper concentration and happier drinking all year round.
It can take about an hour for your body to process just one unit of alcohol.
So the more you consume, the longer it takes for the body to process it.
So if you drank a pint of beer or a large glass of wine with three units, it could take up to three hours to sleep it off.
However, this can vary depending on the size of the person.
'There are many factors that can influence how long it takes to sober up or sleep off alcohol, including how much someone drinks and whether they have eaten, in addition to their age, gender and body composition,' says Dr Oldham.