Hangovers, Why

The cause of hangovers isn't what you think—and other insights from a new group that researches a very old problem.

If you have one too many tonight, among the things you might be wondering tomorrow morning–along with “Where is the Advil?” and “Can everyone please just shhh?”—are a number of existential queries that hangovers, in all their guilt-inducing agony, tend to stir. Like, “Is that ‘hair of the dog’ thing true?” or “Why is it that hangovers always make me swear off drinking forever, yet I don’t?”

AHRG logo

This weekend in Seattle, an unusual group of scientists will gather to mull these and other questions at the meeting of the Alcohol Hangover Research Group. Their logo, fittingly, is a pint of beer next to a spilled glass of red wine.

Hangover research is a bit of a neglected field, not the highest priority in terms of health-research funding. But there’s a lot hangovers can tell us about our brains, our guts, and the epidemiology of alcoholism. In other words, tell me how you feel the morning after getting blitzed, and I’ll tell you what you are.

Ahead of the meeting, I’ve interviewed Richard Stephens, a member of the group and a professor of psychology at Keele University in the U.K., about some of the most surprising things scientists have learned recently about the “gallon distemper.” Stephens has published several papers about hangovers, including whether their severity declines with age. (Answer: Yes. Hang in there, 21-year-olds.)

I also asked him for some scientific hangover-cure recommendations, for a friend.

What are you presenting at the conference today?

We’ve got a quite good research grant from the EU for a two-year project on alcohol hangover, particularly looking at the cognitive effects of hangover. In other words, if you have a hangover, does your memory function normally? And also looking at the link between alcohol hangover and alcohol use disorder. I’m going to be presenting some of the preliminary data from the study on that latter question about hangover and alcohol use disorder. The interest there is that everyone tends to think that hangover is a good thing because it stops you from drinking too much, it’s like the natural brake on drinking. And we all drink too much and that’s a big problem so anything that stops people from drinking too much is a good thing. That’s the kind of folk knowledge.

And yet, a number of studies have actually shown the opposite. If hangover is a natural brake on drinking, then alcoholics should get the least hangovers of anyone—that the reason they are alcoholic is that they don’t have that natural brake on drinking. But actually a number of studies in the U.S. have actually shown the opposite, that alcoholics get the most severe hangovers, even when you control for the amount of alcohol consumed. And so it seems like it’s a more complex relationship between being at risk of alcoholism and hangovers.

Do you have any insights so far in how it affects cognitive functioning?

Yes, we do. The preliminary data are much clearer on the cognitive functioning side. We used a range of cognitive tests, and several of them showed deficits. Which is kind of in-keeping with the wider literature, there’s been probably 20 or 30 studies now looking at the links between hangover and cognitive function.

One of the things that makes our study interesting is just a methodological detail. There are two ways of doing hangover research—one is to do very carefully controlled studies in a lab where you give people measured amounts of alcohol and look at the effects. But the problem with that approach is, apart from the fact that it’s very expensive and resource intensive, that you can only give people fairly mild amounts of alcohol, ethically.

The other way of doing it is a naturalistic study—you get people into the lab the morning after a night when they’ve been out drinking anyway, and look for the natural symptoms of hangover following that episode. The good thing about the naturalistic approach is it’s real drinking and it’s much more ecologically valid, it’s much more mimicking what happens in real life, and that you can get a greater range of alcohol consumption, with some people at the top end drinking much more significant amounts of alcohol than would be allowed in a carefully controlled lab study.

The problem with that approach though, is that people know they’re in a hangover study, because they know that’s why they’ve contacted you, so they probably feel a bit rough and know they don’t have to try very hard because it’s a hangover study anyway. So there are expectancy effects there. So what we’ve done in this study, which is completely novel, is we’ve recruited some people to come into the lab on a morning when they’re likely to have been drinking the night before, but there’s nothing in the information to suggest we’re doing a study on hangover. But where, incidentally, they have been drinking, which in most cases they have, because we timed it that way, we can look at the effects without that expectancy element. Obviously people know they’ve been drinking but they don’t know that we’re interested in that, so in that sense they’re going to be like anybody who turns up to work having been drinking. They’re going to do the best they can with the hangover.

Do we know what causes hangovers?

Not completely, but there’s definitely some fairly good evidence. One component is the way that alcohol is metabolized. When you drink alcohol, there’s an enzyme in the body that breaks down the ethanol in alcohol into metabolites—after you’ve had a drink of alcohol and felt drunk, once you start to feel sober again, that’s because your body has metabolized the ethanol. But once the ethanol has been metabolized, there are usually other alcohols in smaller quantities in alcoholic beverages. One such compound is methanol, and when the body metabolizes methanol, it metabolizes it into toxins—formaldehyde and formic acid. And those make you feel ill, sort of poison you a little bit.

So one part of a hangover is the production of formaldehyde and formic acid, which comes online about 10 or so hours after you’ve been drinking. And the interesting thing about that is that the enzymes in your body that break down alcohols would prefer to break down ethanol first and methanol second. And it means that when you’re in a hangover phase, if you drink more alcohol you’ll actually stop your body from breaking down methanol and the things that are making you feel ill, and instead go back to working on the ethanol and leave the methanol intact. So there is a biological basis for the hair of the dog. And that’s one of the possible risk factors for why hangover might be a risk factor for alcoholism rather than a natural block for it.

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Olga Khazan is a staff writer at The Atlantic, where she covers health.

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