Hour-by-hour, what Christmas booze does to your body – and how to reduce your hangover

Tis the season to be hungover.

But, of course, hangovers aren’t exclusive to Christmas – the average Briton spends more than a year of their life nursing one, according to research by cancer charity Macmillan.

A hangover doesn’t just make you feel rubbish physically – new research by the University of Bristol has found that people who drank the night before performed worse in maths and memory tests the next day, and were less able to control their emotions, too.

Dr Craig Gunn, a lecturer in psychological science who led the study, said: “Hangovers appear to impact most aspects of executive functions (key skills such as problem solving). This substantial impact on individuals and wider society should be considered a public health concern.”

Here, we look at how alcohol affects you from the first sip – and how to minimise hangover symptoms.

Two minutes after you start drinking

Alcohol is absorbed though the mucous membrane lining the stomach and intestine, and passes into the bloodstream.

“About a quarter of it is absorbed via the stomach – the rest is absorbed further along your digestive tract,” explains Debbie Shawcross, a professor of hepatology and medical advisor to the British Liver Trust.

“How quickly you absorb the alcohol depends on factors such as its concentration [drinks with a higher alcohol concentration are absorbed faster] or whether your stomach is empty (food slows absorption).”

After five to 10 minutes

Alcohol very quickly crosses the blood brain barrier – the protective barrier around the brain – where it stimulates the release of ‘feel-good’ chemicals dopamine and serotonin.

This alters the balance of these key chemical messengers (which are responsible for regulating mood and rational thought), reducing inhibitions and leading to impulsive behaviour.

After 30 minutes

A single unit of alcohol (roughly a small glass of wine or half a pint of beer) will have been absorbed by the gut and into the bloodstream, which is when you start to feel tipsy.

After one hour

Alcohol is treated as a toxin by the body – something to be removed – which is the job of the liver.

The liver processes alcohol at ‘a consistent rate of 60 minutes per unit’, explains Professor Shawcross.

Most of the alcohol is broken down by an enzyme called alcohol dehydrogenase and turned into acetaldehyde.

“This chemical is what can cause flushing of the skin, nausea and palpitations often associated with drinking,” she says.

“Other enzymes then break the acetaldehyde down into acetate, which is further broken down into carbon dioxide and water, and eliminated from the body” – in urine, for the most part (which is why trips to the loo become more frequent after an hour’s drinking).

“Some acetate is also expelled in your breath and sweat,” says Professor Shawcross (the reason you can smell drink on someone the day after a heavy night).

“The liver can’t speed up this detoxification process, even faced with excess alcohol,” she adds.

“So even after you stop drinking, alcohol can stay in your blood for up to six hours and in breath for 12 to 24 hours.”

After two hours

If you carry on drinking, you’ll start to move more slowly, your balance will be affected and speech becomes slurred as the alcohol reduces the production of a chemical messenger called GABA in the brain.

After four hours

As the liver struggles to process the alcohol still coming into your system (further affecting coordination and thought processes), the alcohol acts as a sedative, so you start to feel drowsy or pass out.

Hangover symptoms are the result of the lingering alcohol and acetaldehyde in your body

Headache

This is mainly the result of dehydration as you urinate more.

“Passing a lot of urine means you’re also losing electrolytes (such as sodium and potassium), which exacerbates headaches,” says Dr Gunn.

Nausea

Acetaldehyde irritates the gut lining, which can trigger diarrhoea and nausea.

Aches and tiredness

Following heavy alcohol consumption, the immune system releases cytokines (the same protein makes you feel rubbish when you have a cold) to counter damage caused by acetaldehyde.

“But this immune response can also promote feelings of fatigue and muscle ache,” say Dr Gunn.

And as the liver is busy breaking down alcohol, it doesn’t produce as much glucose to maintain normal blood sugar levels, making you tired.

Food cravings

Research shows that people tend to make unhealthy food choices the day after drinking, possibly due to low blood sugar and tiredness.

Sleep problems

Alcohol consumption can affect our body clock and cause fragmented sleep, and that has a knock-on effect on mood and tiredness. In 2019, researchers at the Claude Bernard University in France found that after binge drinking, the body can take several days to return to normal sleep patterns.

Anxiety

Alcohol is a relaxant, so the more you drink, the more relaxing brain chemicals – such as dopamine – are released.

This prompts your confused brain to try to restore the balance the next day by releasing chemicals that have a stimulating effect, such as cortisol.

This leads to an increased heart rate and feelings of anxiety.

“Studies show that people view normally pleasant images – cute bunnies, for example – less favourably when hungover,” says Dr Gunn.

“Your normal ability to regulate emotions and how you experience pain appear important – and the more an individual catastrophises pain and emotions generally, the greater severity of hangovers they have.”

Generally, the more you drink the worse you feel the next day.

“But we now think this is different for everyone and may be related to how drunk you believe you are, rather than simply down to the amount of alcohol consumed,” says Dr Gunn.

Alcohol also hits women harder as they have lower levels of alcohol dehydrogenase – the enzyme that breaks it down.

And hangovers get worse with age because “the activity of the enzymes that break down alcohol is reduced, so it is more slowly metabolised and acetaldehyde levels take longer to be dealt with”, says Professor Shawcross.

As for hangover remedies, do any of them work?

“In short, no,” says Dr Gunn.

“The best way to limit a hangover is to consume alcohol in moderation.”

But the following may help:

• Don’t drink on an empty stomach;
• Sip water or non-fizzy drinks between alcoholic ones to reduce the burden on your liver;
• Drink lots of water before bed.