Hangover Science

According to the NHS, it takes roughly one hour for the human body to process one unit of alcohol which, for anyone who is intent on having more than one glass of wine in a night (i.e. most of us, a lot of the time) can be a problem. Units are the building blocks of inebriation, and once that wall’s been built, it’s only a matter of time before it has to come down again, and it does so in the brain-aching rockslide that we all know and love – the hangover.

Lots of drinking causes a hangover, we all know this. But which part (or parts) of the drinking is it that actually instigates the misery? The answer is that there doesn’t seem to be a single, primary culprit, but rather a whole plethora of factors and variables that can influence one or several of the symptoms we group under the umbrella term, a ‘hangover.’ A sore head, nausea, dizziness and dehydration all have subtly different root causes that, when combined in significant quantities, can prove a rather nasty cocktail. The sore head, for instance, can be traced to a variety of different things, but one of the primary causes is a chemical known as acetaldehyde.

Acetaldehyde is a product of the fermentation reaction (but can also be produced through oxidation) and contributes to fruity flavour characteristics redolent of green apples and hay when present in a wine and low quantities. It is however, a poison, and although the human liver naturally produces acetaldehyde to process the by-products of alcohol, a substantial ingress into the body can prove too much to cope with, and prompt reactions such as headaches and accompanying evacuative procedures like vomiting. Can you avoid it? No, in short – it’s a necessary product of all fermentation reactions. Red wines typically contain less acetaldehyde than white wines, but they often tend to have a higher overall alcohol content (ABV)...so damned if you do, damned if you don’t.

Acetaldehyde is one of the larger chemical culprits, but another group of chemicals known as congeners also have a significant role to play. Once again, congeners are a by-product of fermentation, and are the impurities responsible for many of the desirable flavour compounds found in alcoholic drinks. Their prevalence tends to be greater in darker coloured drinks; bourbon, rum, brandy, dark fruit liqueurs and, you guessed it, red wine. The congeners aggravate the irritant effects of the ethanol, and are increasingly considered responsible for some of the more potent morning-after headaches.

Another big hangover cause is dehydration. Ethanol is a diuretic – and a powerful one at that. Basically, it makes you urinate more. One drink is commonly followed by several trips to the toilet, and all this ejection drains our bodies of fluid extremely quickly. The subsequent dehydration – felt particularly keenly early next morning – can lead to severe dizziness, acute headaches, and (one of the least severe side-effects, but one of the most embarrassing on a night out) halitosis, a.k.a., bad breath. Dry eyes are another result of dehydration, and sustained dryness can combine with the blood vessel-relaxant qualities of alcohol consumption to make the eyes appear sore, strained and bloodshot the next day.

Naturally therefore, the logical thing to do would be to ensure a steady and regular intake of water between drinks, but experiments have cast doubt on whether rehydration in this form actually counters any of the light-headedness at all. Yes, it will quench your thirst, but no, it won’t make you walk any straighter.

Then of course, there are the harder to define (and often harder to deal with) factors that contribute to the hangover – genetics for a start. Variances with alleles associated with the processing of aldehyde dehydrogenase (alcohol, essentially) and turning it into the afore-mentioned acetaldehyde are common in people of Asian ethnicity. Acetaldehyde therefore, builds up far more quickly, leading to both a faster and more sustained intoxication and, as you’d expect, a much harder comedown. Studies have also suggested that there may be a correlation between hangovers and age, with adolescents less prone and those over the age of 40 more so – largely, once again, because of the body’s decreasing ability to process alcohol dehydrogenase.

The received wisdom that women get drunk faster than men seems to be true (a result of the lower-average bodyweight) although the science is currently out as to whether speed of intoxication will evolve into potency of hangover. Unavoidables aside, a more manageable hangover cause has been shown to be cigarette smoking. Smoking whilst drinking increases the absorption rate of our friend acetaldehyde, and the subsequent pain-rate of tomorrow’s hangover.

So, what about the cure? Is there an art to drinking lots of wine with no side-effects? No. Alcohol will get you drunk and drunkenness can cause hangovers. All the above factors are influences in their own right, but the irritancy of ethanol on the body is the overarching factor linking and aggravating all of them. Steadier drinking seems to be the most sure-fire solution, spacing out your glasses and allowing the body time to process some of the toxins.

Drinking water will help keep you hydrated and stave off the headaches (though not, as we’ve seen, the light-headedness) while avoiding other substances like cigarettes is clearly a good idea. Red wine unfortunately is, as we’ve seen, high in congeners and ABV (compared to beers and cider) so drink it slowly and steadily. Drinking wine is about pleasure after all – a sensual, gustatory experience. If your motives are other, best drink that crate of lager. Save the Bordeaux for a quieter time.