As you’ll know if you’ve ever experienced it, blacking out is a strange experience. You are, by all accounts, fully functioning, but you have no awareness of what you’re actually doing. Stuff happens—you walk around, you talk to people, you dance on top of a pool table naked—but only with the help of friends/eyewitnesses do you later learn of these things.
The next morning, between wincing in embarrassment and moaning in pain, you scratch your head in disbelief, incredulous that you could even stand upright with so much alcohol coursing through your veins, let alone carry on a conversation.
So how the heck does this work?
To find out, we looked at the incredibly detailed work of Aaron M. White, a prominent doctor of psychiatry who’s been studying alcohol-related blackouts for years, both as a professor at Duke and now as a senior scientific advisor at the National Institute on Alcohol Abuse and Alcoholism, a division of the National Institutes of Health.
There are two categories of blackouts, according to White’s research: en bloc blackouts, where people remember literally nothing past a certain point, and fragmentary blackouts, where they can recall moments or vignettes of a severely drunken episode.
While several studies show that fragmentary blackouts are far more common, both work pretty much the same way: High amounts of alcohol essentially disrupt your brain’s ability to form new long-term memories. This means in the middle of a blackout, you may be able to recall what happened a few seconds ago, but your brain can’t store this information. Or put another way, you’re still technically functional, it’s just that your brain isn’t automatically saving and backing up the data as the night goes on.
You won’t be surprised to learn that the research shows it takes a lot of alcohol to enter blackout mode: Between 0.24 percent and 0.30 percent blood-alcohol content (or roughly the equivalent of a skinny dude chugging 10 drinks in an hour). This is a dangerously large amount of booze to have in your bloodstream. For comparison’s sake, the legal driving limit is 0.08. Surveys have shown that men and women experience them roughly equally, despite the fact that it takes a lot more alcohol for men to blackout, owing to body mass and the physiological differences between the sexes.
The big question, then, is how to prevent them. Drinking quickly and copiously doesn’t help. Nor does drinking on an empty stomach. As for the type of alcohol, liquor is a major contributor (in studies, people rarely reported blacking out by sticking only to beer). Other drugs—pot, Valium, Xanax, Rohypnol etc—can bring on blackouts far more easily, too. Studies also show that people who regularly binge drink are more likely to suffer blackouts. (It’s basically a positive feedback loop where the more often you get them, the more prone you are to getting them in the future.) Genetics are a big factor as well. White’s research even shows that prenatal alcohol exposure can make people more prone to blacking out.
So if you don’t want Wednesday 18 March 2020 to be full of dread and wonder, ruined by a surprise vomiting fit, the whole experience is best avoided.