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Fade to black: why we black out when we drink.

Author: The Simple Bit

Category: Science

If you’ve ever woken up the morning after drinking with no memory of how you got there, then you know what a blackout is. But do you know why they happen? And that there are two kinds?

The simple bits:


  • Blackouts happen when alcohol prevents neurotransmitters from imprinting memories
  • There are two kinds of blackouts – En bloc and fragmentary 
  • With fragmentary blackouts, you can have your memory jogged
  • Other factors – like the pace of drinking – can be a factor in blackouts
  • Drink safe, friends



We’ve already talked about what alcohol can do to your brain (to save you a click, it affects your reaction times, concentration, balance, coordination and even your speech). But you might not even remember one of the freakiest effects of drinking: blacking out. 

What are blackouts?

Blackouts are when you drink to forget – literally. They’re basically periods of amnesia when alcohol prevents neurotransmitters from imprinting memories from short-term memory to long-term memory. It means the drinker can have conversations, meet new people, and later have no memory of it happening. 

If there’s any good news to be had, these periods of amnesia are mostly “anterograde,” meaning that alcohol impairs forming new memories while you’re drunk, but it doesn’t typically erase memories from before you got drunk. (Which is good, I guess). 

The drinker can have conversations, meet new people, and later have no memory of it happening. 

The two kinds of blackout

There are two types of blackouts – ‘En bloc’ (or complete) and ‘fragmentary’ (or partial) blackouts. With ‘En bloc’ blackouts, you can’t for the life of you remember what happened, regardless of what kind of hints and clues you’re given. With ‘fragmentary’ blackouts, you can usually piece things together when people give you prompts. 

While drinking to excess brings blackouts on, the way you drink can be a contributing factor. Gulping drinks quickly, drinking on an empty stomach and mixing booze with illicit substances can all contribute to blackouts. The rapid rise in Blood Alcohol Content (BAC) is thought to be a factor here. One study found that mixing alcohol and illicit substances led to complete blackouts more often. 

How can I avoid them?

Avoid drinking to excess, basically. It sounds obvious, but Drinkwise are pretty good at laying it out for you. Eat a meal before you drink, slow things down, alternate between alcohol and water and switch in a low alcohol drink every now and then. It’s probably worth noting that there is a school of thought that if you’ve had a blackout in the past, you might be more susceptible to them in the future. If this sounds like you, take it particularly easy. Drink safe, friends. You’re more likely to remember the good times.

Blackouts are serious business and not to be taken lightly. If you think you, or someone you know might have a problem with alcohol, talk to your doctor, visit DrinkWise, or call your state/territory alcohol and drug helpline.