Alcohol blackouts are often depicted in pop culture as strange but comedic experiences where characters have to retrace their steps to solve a mystery. However, amnesia, even when it’s alcohol-induced, is rarely a pleasant experience. Waking up with little to no memory of the night before can be unnerving. How did you get home or wherever you spent the night? What happened to you during your memory lapse? Alcohol blackouts can be scary, and they also mean that you drank enough to have a severe impact on your brain. 

What does an alcohol blackout do to your brain, and what are the long-term effects of frequent binge drinking. Learn more about alcohol’s effects on your brain. 

What Causes a Blackout?

A blackout is a period of memory lapse caused by the effects of alcohol on the brain and nervous system. An alcohol blackout is sometimes called alcohol-induced amnesia. It’s usually experienced as a failure to recall the events that you experienced after a certain point while drinking excessively. Blackouts are usually temporary, though excessive alcohol use can lead to a disorder that causes frequent memory impairment. fetal alcohol syndrome in adults

A blackout doesn’t necessarily mean you passed out or lost consciousness at some point. While losing consciousness can happen while binge drinking, you can remain awake and aware throughout a blackout period. 

Not everyone who drinks or gets drunk will experience an alcohol blackout. It’s most common among binge drinkers, and your risk of a blackout will increase with your blood alcohol level (BAC). BAC is the concentration of alcohol in your blood. It’s used to measure intoxication severity because it indicates the amount of alcohol that could reach your brain. Your liver filters alcohol out of your blood, but it can only handle so much. If you drink more than two to three drinks in an hour, alcohol can start to affect your brain.

But What Does Alcohol Do to Affect Your Memory? 

A blackout has to do with short- and long-term memory, a function of your brain when new information is stored in your prefrontal cortex. These short-term memories are small bits of information that are stored as they occur. Another part of the brain called the hippocampus transfers short-term memory into long-term memory as a whole connected experience rather than brief snippets of information. 

When your BAC reaches a certain level, alcohol prevents certain chemical messengers in the brain from working normally. This prevents you from storing information properly, which prevents you from forming a complete picture of an event in long-term memory. 

Signs and Symptoms of a Blackout


Blackouts can be difficult to notice when they’re occurring. You may realize it only when there are gaps in your memory the next day. While they’re occurring, you may be fully aware with no obvious memory issues. During a blackout, new information may fail to make its way into long-term memory, but old memories aren’t affected. Your friends may have conversations with you that seem normal, with no apparent memory impairment. 

However, blackouts occur with high BACs, so you’re likely to experience other symptoms of alcohol intoxication. Your risk of a blackout begins at a BAC of 0.16%. This is well past the legal driving limit and the beginning of severe alcohol-impairment. At this BAC, you may experience impaired judgment, slower reaction time, slurred speech, lowered motor skills, and drowsiness. Physical symptoms like nausea and vomiting are common.

If you continue to drink, your risk of a total blackout will increase. At a 0.3% BAC and higher, blackouts are likely, and you will probably also experience a severe loss in motor function. You may not be able to complete thoughts or carry on conversations. You may also pass out. You may have alcohol poisoning at this point. 

Types of Blackout


There are two types of blackouts that depend on your BAC. At a BAC of 0.16%, you will likely experience some memory impairment, but it may not be a complete memory gap. For instance, you may have some disconnected memories that are difficult to put together as a whole event. This is called a fragmentary blackout, but it’s also called a gray out or a brownout. For example, you may remember talking to a person without remembering what you talked about or when you stopped talking to them. 

At a BAC of 0.3%, you may experience total memory loss between a certain moment when you were binge drinking to when the effects wear off. This is called an en bloc blackout or a total blackout. This involves total memory loss during a certain time. You may experience this by waking up without knowing how you got to your location.

Can Alcohol Blackouts Lead to Overdose?


A blackout itself doesn’t cause overdose symptoms, but if you’ve experienced a blackout, it means you risked alcohol poisoning. An alcohol overdose may cause unconsciousness, coma, slowed breathing, and slowed heart rate. In cases where alcohol intoxication becomes fatal, respiratory depression leads to oxygen deprivation and death. 

Alcohol is a central nervous system depressant, which means it works to slow down activity in your brain and body. Moderate alcohol can make you feel relaxed and maybe a little sleepy. But too much alcohol can start to slow down important brain and nervous system functions.

A blackout probably means you’ve experienced a nonfatal overdose with symptoms like vomiting, loss of consciousness, next-day drowsiness, headache, dehydration, seizures, and hypothermia. If you’ve experienced a blackout, it means you’ve really taxed your brain and body, risking serious overdose symptoms. 

Are Alcohol Blackouts Signs of an Alcohol Use Disorder?


Blackouts are usually caused by binge drinking, which is a sign of alcohol misuse. It’s possible to experience a blackout without developing alcohol use disorder. However, frequent blackouts likely mean you have a problem with alcohol. 

Alcohol use disorders are diagnosed based on severity. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) lists several factors that could point to a substance use problem, like trying and failing to quit or experiencing growing tolerance. 

There are 11 signs and symptoms in total, and experiencing two or three of them indicates a mild disorder. Four or five points to a moderate disorder. If you experience six or more, you may have a severe substance use disorder. 

What Are the Long-Term Health Effects of a Blackout?

A blackout is a sure sign of alcohol misuse. You drink to the point of significantly impairing brain and nervous system functions. Alcoholism is linked to many long-term health problems, including various types of cancer, liver disease, and kidney disease. However, long-term heavy alcohol use can also affect your brain. Research indicates that chronic alcoholism can actually shrink your brain. It may also cause early cognitive decline as you age. That means you might experience memory problems earlier in life than you would normally.

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