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Key Points

  • An alcohol-induced blackout refers to a state where an intoxicated person loses the ability to create new memories, despite remaining awake and appearing to function normally.
  • A blackout is not the same as passing out; passing out results in a loss of consciousness, while a blackout affects memory only.
  • Blackouts are caused by a rapid rise in blood alcohol concentration, which disrupts the hippocampus’s ability to store short-term memories as long-term ones.
  • Blackouts can vary greatly in severity from fragmentary blackouts resulting in only partial memory loss to en bloc blackouts resulting in complete memory loss with no recall of that certain period of time.
  • Frequent blackouts can be indicative of alcohol use disorder. It would be beneficial to discuss these incidents openly with a healthcare professional.

Most people have heard the term “blackout drunk,” and many have personally experienced it or have seen it happen to a friend.

However, being “blackout drunk” isn’t just a hazy memory or merely a funny story. Rather, it signifies that alcohol has disrupted the brain’s capacity to form memories, and understanding how this happens can provide insight into the larger issue of excessive alcohol consumption.

Every day at Ikon Recovery, we interact with people who express concern regarding their relationship with alcohol. Many of these people reference blacking out as one of the initial warning signs. Read on for more information about blackouts, what creates this phenomenon, and what it might be telling you about your drinking habits.

What Is a Blackout?

An alcohol-induced blackout refers to a state where someone consumes enough alcohol that their brain temporarily loses the ability to create new memories, yet remains conscious and appears to be functioning normally.[1]

A common misperception is that a blackout involves the loss of consciousness. This is not true. During a blackout, a person can hold conversations, walk around, operate vehicles, and make decisions. To the people around them, they may not even seem that intoxicated at all. The difference is that none of the events occurring throughout the blackout are retained in that person’s memory.

While everyone experiences blackouts differently, researchers identify three primary types depending upon how much memory is lost:

  • Fragmentary blackout (also called grayout or brownout): Partial memory loss with islands of clear memory in between that can be recalled with prompting.
  • En bloc blackout: A total memory loss for a specific length of time; the person will not be able to remember anything, even with prompting, because the memory was never formed to begin with.

What Causes Blackouts When Drinking Alcohol?

Alcohol-induced blackouts occur due to how alcohol impacts the hippocampus — the area of the brain involved in creating memory. When blood alcohol content (BAC) rises rapidly, it blocks NMDA receptors in the brain and enhances GABA activity in the hippocampus, both of which interfere with long-term memory storage.[2] Without that process functioning properly, the hippocampus is unable to turn short-term memories into long-term storage. A person will experience the activity or behavior during the moment, but those events are not captured and cannot be recalled later, no matter how hard they try.

Several factors contribute to an increased likelihood of an alcohol-induced blackout:

  • Binge drinking, or drinking a large amount of alcohol in a short period of time
  • Drinking without eating first, which accelerates how quickly alcohol is absorbed into the bloodstream
  • A rapid increase in blood alcohol concentration (BAC) rather than a slow, steady one
  • Weight, sex, and tolerance all factor into how efficiently a person’s body processes alcohol
  • Combining alcohol with certain prescription medications which intensify its impact on the brain

When blood alcohol content rises quickly, this disruption of memory storage becomes more severe, which is why blackouts are so closely tied to how fast BAC climbs rather than the total amount consumed.[3] This makes it possible to develop a blackout after consuming what may seem like a small amount of alcohol — and the person may not feel intoxicated at the time.

Waking up with no memory of part or all of the previous evening

Symptoms of a Blackout

Unfortunately, the signs that you’ve had a blackout episode are only clear once it’s over, not during. Common symptoms include

  • Waking up with no memory of part or all of the previous evening or period of time that heavy drinking occurred.
  • Realizing you cannot remember important details after binge drinking, including things like how you got home, what you said, or how a night ended
  • Friends describing events or conversations you have no memory of at all
  • Finding messages, purchases, destruction, or other evidence of things you don’t remember doing
  • Feeling a sense of dread or anxiety because you are not sure of what happened during the time you can’t recall

A person having a blackout has no way of knowing it’s happening to them in real time, which is why these signs are usually easier for someone else to catch than for the person experiencing them. It is worth noting if your friends or family are often describing events or behavior that you have no recollection of.

Blackouts vs. Passing Out

Passing out and blacking out are not the same thing, though both can occur due to overconsumption of alcohol and often happen back-to-back as BAC levels rise.

Passing out happens when alcohol depresses brain function to the point that a person loses consciousness, a sign of severe alcohol intoxication that can become life-threatening.[4] A blackout is distinctively different. A person experiencing a blackout can be completely awake and functioning normally, only failing to transfer short-term memory into long-term memory.

This is often why blackouts are so disturbing in hindsight. People around the person may recount numerous events from an evening, yet the person who was blackout drunk cannot recall any of it despite appearing attentive at the time.

The Risks Beyond Memory Loss

Although memory loss is a significant part of a blackout episode, it is not the only risk.

Because you are still functioning during a blackout, you can still engage in risky behavior that you never would while sober, all without the opportunity to reflect on those choices in order to learn from them. People can drive under the influence of alcohol while in a blackout state, walk into hazardous environments, or make decisions that place themselves at risk.

Blackout episodes can also serve as early warnings of excessive alcohol consumption. Drinking heavily enough to experience blackouts is associated with an increased risk of acute alcohol intoxication and alcohol overdose (or alcohol poisoning).[5] Studies have shown that repeated episodes of alcohol-induced blackouts are associated with impairment to brain functions and cognitive processes, leading many binge drinkers and their families to question the long-term implications on memory and brain health.[6]

Are Blackouts a Sign of Alcohol Use Disorder?

While not every person who experiences a single blackout episode is dependent on alcohol, multiple instances of frequent blackout episodes should raise concern. If a person consistently finds themselves drinking enough to result in blackouts, or is drinking specifically to reach that point, this could indicate an ongoing addiction to alcohol.

To help assess a potential problem related to drinking, ask yourself:

  • Do you usually drink until you black out on a consistent basis?
  • Have you experienced two or more alcohol-related blackout episodes within the last year?
  • Do you find yourself unable to stop drinking once you start?
  • Have family members or friends expressed concern regarding your drinking habits or your memory after you drink?

If you answer “yes” to several of these questions, it may be time for an open discussion with a medical professional concerning your history of alcohol consumption and what forms of support may be available to you.

Rethinking Your Relationship With Alcohol

Alcohol is a part of many people’s lives, but for some, the social aspect of drinking becomes a serious dependency issue.

If your own binge drinking or blackout episodes have developed into a larger problem related to alcohol use, now might be the right time to get real support. Support groups, therapy, and structured addiction treatment are all available in New Jersey and can be the right choice depending on where you are in your relationship with alcohol.

Ikon Recovery provides treatment for those struggling with alcohol addiction by offering several different levels of care to fit the unique needs of each person who comes through our doors. A blackout is usually one of the most obvious indicators that a person has lost control over their alcohol use and that alcohol is now in charge.

If you or someone you love is experiencing alcohol-induced blackouts, memory loss, or other signs of a growing dependence on alcohol, we’re here to help. Contact Ikon Recovery today to schedule a free, confidential consultation and take the first step toward getting real support.

Frequently Asked Questions About Being Blackout Drunk & Alcohol Induced Blackouts

What is a blackout?

A blackout is a period of memory loss caused by alcohol’s impact on the hippocampus. Unlike passing out, a blackout does not involve losing consciousness; it involves the inability to retain memories created during that window of time.

What causes blackouts when drinking alcohol?

Blackouts are primarily caused by a rapid increase in blood alcohol levels that interferes with the brain’s ability to transition short-term memories into long-term storage. Individual factors such as binge drinking, consuming alcohol on an empty stomach, and personal tolerance contribute significantly to the likelihood of experiencing a blackout.

What are common symptoms of a drunk blackout?

Commonly observed signs include repeating questions or stories, participation in risky behaviors without memory of it later, and waking up with gaps in memory for part or all of the period where alcohol was consumed. Typically, friends and family members notice the lack of memory before the person themselves recognizes it.

Can blackouts be prevented?

While prevention is not entirely possible, even moderate consumption can occasionally cause blackouts; limiting the quantity consumed and slowing the rate of consumption will lower the chances of having a blackout.

Sources

[1] [3] National Institute on Alcohol Abuse and Alcoholism. (2025). Interrupted memories: Alcohol-induced blackouts. https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/interrupted-memories-alcohol-induced-blackouts

[2] White, A. M. (2003). What happened? Alcohol, memory blackouts, and the brain. Alcohol Research & Health, 27(2), 186–196. https://pmc.ncbi.nlm.nih.gov/articles/PMC6668891/

[4] [5] National Institute on Alcohol Abuse and Alcoholism. (2025). Understanding the dangers of alcohol overdose. https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/understanding-dangers-of-alcohol-overdose 

[6] Wetherill, R. R., & Fromme, K. (2016). Alcohol-induced blackouts: A review of recent clinical research with practical implications and recommendations for future studies. Alcoholism: Clinical and Experimental Research, 40(5), 922–935. https://pmc.ncbi.nlm.nih.gov/articles/PMC4844761/