Alcohol use and memory loss — blackouts?

Originally Published: April 26, 1996 - Last Updated / Reviewed On: August 28, 2014
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Dear Alice,

What exactly does "blacking out" from alcohol mean? Can people get so drunk that it is physiologically impossible for them to remember what happened the next day? Also, is it possible for someone to walk around, talk to people, etc., and then have no way of remembering those actions?

Dear Reader,

Let’s go ahead and clear the fog around the nature of blackouts. Blackouts due to alcohol use occur when large amounts are consumed quickly, creating a rapid rise in blood alcohol content (BAC). You asked whether people can get so drunk that it’s physiologically impossible to remember what happened the next day, and the answer is yes. Alcohol-induced blackouts affect the functioning of the hippocampus, a part of brain that plays a significant role in the formation, storage, and creation of meaning in memories. More specifically, alcohol impedes the ability for information to transfer from short-term memory to long-term storage, which results in the impairment of memory creation. Also, the exact ability to recall memories after a blackout can vary. Two types of alcohol-induced blackouts have been identified: en bloc (total) or fragmented (partial) memory lapses. Someone who experiences an en bloc blackout is unable to recall any information from a specific period of time. Total blackouts typically occur when a person has a higher BAC. Fragmented blackouts are more common, occur at lower BACs, and may allow for some amount of memory recall.

Intoxicated people will likely experience cognitive and memory impairments before physical functioning is visibly affected. Blackouts are also different from passing out, which is marked by a visible change in consciousness – basically a person stops functioning and may appear to be asleep. Unlike passing out, a person experiencing a blackout may appear to “function normally.” Because they are able to use working and short-term memory to carry on conversations and engage in complex behaviors, it can be difficult to identify who might be experiencing a black out. The information gathered during black out activities, however, is not stored in long-term memory and retrieval of memories can be limited or lost. For example, you and your friends could go to a bar tonight, have some drinks, and talk about politics. But tomorrow, when your friends recall in detail the previous evening's discourse, you may not recall the actual conversation even though you appeared, at the time, to be a full and competent participant.

The risk of blacking out due to alcohol use varies from person to person. While common among those who misuse and abuse alcohol, blackouts are also experienced by social drinkers. Blacking out can be a warning sign to drinkers and their friends that alcohol-related problems exist. Due to physiological differences, women are more vulnerable to blackouts than men, even if they are consuming alcohol at lower rates. Additionally, women don’t recover from memory impairments as quickly as men. When serious and typically unforgettable occurrences are impossible to remember, for high-risk and social drinkers alike, blackouts are often troubling or traumatic.

It’s no secret that judgment, decision-making, and interpretation of social signals are often impaired when using alcohol. This is the case even if an intoxicated person seems to be fully aware and competent, because, as previously mentioned, it can be difficult to distinguish who might be experiencing a blackout. Now, while you didn’t mention this in your question, it’s worth discussing here: The majority of college students involved in acquaintance rape had been drinking alcohol or using drugs. Even more alarming is this: there’s evidence suggesting that perpetrators of rape will use alcohol purposefully as either a rationale for raping (saying things like: “I was drunk, I didn’t know what I was doing,”) or as a tool for incapacitating their victims. At Columbia, this is expressly prohibited in the Gender-Based Misconduct Policy. All of this to say, watch out for your friends, especially while drinking. If you see a friend, acquaintance, or even someone you don’t know who is getting drunk and it seems like someone is trying to become intimate with them, you can step up and intervene in the situation. This could be as simple as asking the person if they are okay or helping them find a safe way home, especially if they seem uncomfortable with the situation. Also, if you are ever in a situation where you are with someone who has been drinking, it is best to wait until everyone is sober to ask for or give consent.

What can be done do to prevent blackouts? Cutting back or setting drinking limits for your drinking is one option. For low-risk drinking tips, check out Hangover helper and tips for healthy drinking. If you’re concerned that blacking out has become a common occurrence or that your drinking has become a concern, consider talking with someone about your drinking behavior. If you’re a student at Columbia, you can take the online anonymous alcohol self-assessment to learn more about your own drinking behaviors. Columbia students can also make an appointment at Counseling and Psychological Services (Morningside) or the Mental Health Service (CUMC) to speak with a counselor about her/his alcohol use in a non-judgmental environment. The National Institute on Alcohol Abuse and Alcoholism’s Rethinking Drinking website also offers information and resources to explore your drinking and ways to cut back or quit.

Remember, if you decide to drink, drinking safely and responsibly will increase your chances of having a great night you won't forget.