Our in-house Know-It-Alls answer questions about your interactions with
technology and science.
Q: What Causes Hangovers, and How Can I Avoid Them?
A: The winter holidays require much of usmindfulness of tradition (both religious and familial), emotional forbearance (both general and familial), financial judgment, good cheer (real or pretend), and, for some, a higher-than-usual intake of alcohol. For people who indulge, the seasons parties, vacation time, and family gatherings invite over indulgence. That, in turn, invites some pretty miserable mornings after.
If youve ever had a hangover, you know what Im talking about. Or maybe you dont, because symptoms vary when people let their blood alcohol levels climb up past tipsyspace and then crash back down to zero-point-zero. Some people report never getting hangovers at all. (There might be some genetic variation here in terms of susceptibility and speed of ethanol metabolism, but one study of Dutch students who said they never get hangovers showed that it was because they simply hadnt drunkdrinked? drank?enough). Some people wear them in their guts and others wear them in their heads. But you probably know the general drill: headache, diarrhea, loss of appetite, dehydration, nausea, tiredness, decreased coordination, cognitive impairment, and a general sense of feeling like crap.
Scientists do not know much more than that about the condition of hangover. Theyre not sure what causes it, and they definitely dont know how to fix it. Its poorly studied. And the world is full of untested, self-styled hangover remedies. The outlook aint great.
Still, the rough outlines of a hangover arent complicated. If you dont consume alcohol, you wont get one. If you drink enough to get to 0.1 percent blood alcohol contenta somewhat arbitrary number, but lets stick with ityou get a snowballing set of physiological consequences. Ethanol, the specific alcohol in booze, is a teeny-tiny molecule that slips between and into cells; it acts as a depressant in the gut, slowing down motility. From the GI tract the ethanol heads for the liver, where an enzyme called alcohol dehydrogenase begins the process of breaking it down.
If you drink enough alcohol to outpace the livers processing capacity, the ethanol makes its way via the bloodstream to other organs. It suppresses the production of vasopressin, also known as Antidiuretic Hormone, which is why drinking makes you pee and why it dehydrates you. In the brain, it migrates from the frontal cortex (where you do your thinking and being) to regions of the brain responsible for self-governing and reward processing, and then at higher concentrations to the parts responsible for for memory, and then motor coordination. Nobody really knows how. Thats drunkenness, and it seems to operate via the same neural architecture that benzodiazepines like Valium do. You feel good, then you feel sleepy, then you feel bad.
Just as no one really knows how drunkenness works, no ones really sure about the specifics of the hangover, either. Once your body has finished processing all that ethanol, maybe a dozen hours later, that whole other set of unpleasant symptoms show up. Researchers have advanced various hypotheses about the mechanism over about the last century or so. (It looks like alcohol withdrawal! It could be electrolyte imbalance! Its some other non-alcohol ingredient in the booze, a congener! Maybe its the acetaldehyde that comes from metabolizing the alcohol!) Some studies show hints of oxidative stress. Ethanol might contribute to a leaky gut; in a (very, very preliminary) study, three months of probiotic treatment seemed to reduce inflammation, reduce injury to the liver, and reduce overall alcohol consumption which also cut down hangovers.