It's never comforting to hear a story about a drunken night out that you don't remember. Not only is it super freaky to feel like you have a doppelgänger out there who's a little (or a lot) more adventurous than you are, blackouts can also feel unpredictable.
Why is it that they seem to happen randomly on some nights, but not others, no matter how much you drink? How is it possible that you seemed normal, yet you were drunk enough to not remember how you made it home? Luckily, researchers are learning a lot about the answers to these questions — and the best ways to prevent blackouts from happening in the first place (without skipping the party).
"When you black out, [you've drunk] to a point that you’re still able to interact with your environment — you’re still having conversations — but your brain isn't able to make the memories for what’s going on," explains Reagen Wetherill, PhD, who co-authored a review of the research on blackouts in April.
This happens because of the way alcohol interferes with your brain. To create a memory, you first have to take in information from your environment. That information then hangs out in your short-term memory, which keeps track of what's happening in the moment. Then, for something to stick in your long-term memory, that specific connection between your neurons needs to physically change and get stronger. That happens with the help of chemical messengers (neurotransmitters) in your brain, such as GABA, glutamate, and acetylcholine.
But alcohol affects the release of nearly every neurotransmitter in your brain — and it does so in the hippocampus in particular, an area that we know is extremely important for making long-term memories. (The hippocampus is one of the areas in the brain that Alzheimer's disease damages.) "These [neurotransmitters] are kind of the bread-and-butter that makes the brain work the way it does," Dr. Wetherill says. "But alcohol interferes with the neurons in this part of the brain such that the processes that go into making a memory are interrupted."
The processes that go into making a memory are interrupted.
Dr. Reagan Wetherill
Specifically, alcohol takes away your ability to transfer something from your short-term memory into long-term memory. And even more specifically, it affects your ability to create "episodic" memories. "That's the memory for what's really going on in one's life, such as what happened on Friday of last week," as opposed to straight facts, explains Dr. Wetherill.
However, your short-term memory isn't affected. This is why you'll seem totally normal (or, you know, normally drunk) while you're partying. It's only when your memory is tested later that you'll realise something was up.
Blackouts are definitely not an experience you want to be having very often. Aside from the general creepiness of not knowing what you were doing for a chunk of time, blackouts aren't great for your memory overall. For one thing, Dr. Wetherill's research has shown that having one blackout makes another one much more likely. And those who report blacking out show differences in their brain activity while performing memory tasks compared to those who don't black out when given the same amount of alcohol.
The more alcohol you consume, the more likely it is that you’re going to have memory problems.
Dr. Reagan Wetherill
Older participants who have been chronic heavy drinkers show even more significant memory deficits, and their brains can actually atrophy — similar to the effects of a severe vitamin deficiency. But if you're regularly drinking to the point of blacking out at a younger age, you're already incurring damage that isn't going to be repaired. "It's a 'You'll never be who you once were' kind of thing," Dr. Wetherill says.
So how can you stop it? First of all, the obvious: "The more alcohol you consume, the more likely it is that you’re going to have memory problems," Dr. Wetherill says. But researchers have uncovered a few other specific factors that make blackouts more likely. Drinking a lot at once quickly, like you might do during "pre-gaming" or drinking games, and drinking sugary, liquor-masking cocktails can up your risk for a blackout. So, the old rules apply here: If you're drinking alcohol, avoid multiple shots or chugging, eat before you go out, and drink water (ideally alternating one glass of water for every alcoholic beverage you imbibe).
You can also have a genetic predisposition to blacking out, which is, of course, hard to control. This means that if you have a family history of alcohol problems or you simply feel like you seem to experience blackouts more than your friends, it's especially important to stick to responsible drinking behaviours to keep your brain sharp (and to remember all your excellent party times).