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Alcohol Blackouts | Types, Causes, & Dangers

Published on August 18, 2021
Alcohol Blackouts | Types, Causes, & Dangers

Have you ever forgotten some or all of what happened while you were drunk? You likely experienced a type of memory loss called an alcohol-induced blackout.

Like other forms of memory loss, alcohol blackouts pose serious risks, including physical injuries, legal problems, and damaged relationships. If you frequently experience blackouts or loss of memory from alcohol abuse, you may be struggling with addiction. 

Types Of Alcohol Blackouts

Researchers have identified two main types of blackouts: fragmentary blackouts and complete blackouts.

Fragmentary Blackouts

A fragmentary blackout is the most common type of blackout. It’s sometimes called a “brownout” or “gray out.” That’s because it only causes partial memory loss. 

In other words, you’ll forget some things that happened while you were drunk, but not everything. You may also be able to recover lost memories via reminders or cues. 

Complete Blackout

A complete blackout (also called an en bloc blackout) makes you forget everything that happened while you were blackout drunk. In most cases, you won’t be able to recover lost memories, even with reminders or cues. 

Whether fragmentary or complete, blacking out does not make you lose consciousness. Instead, you remain awake and aware, but your brain loses the ability to store new memories. 

What Causes Alcohol Blackouts?

A blackout occurs when alcohol disrupts the process of memory formation. Specifically, it prevents short-term memories from moving to long-term storage in a part of the brain called the hippocampus. 

You’re more likely to experience a blackout when you have a high blood alcohol concentration (BAC). BAC refers to the amount of alcohol in a person’s bloodstream (also called blood alcohol level). 

Most blackouts occur in people who have a BAC of at least 0.16% (which is almost twice the legal driving limit), especially if it rises quickly. 

BAC & Binge Drinking

Your BAC tends to rise quickly when you binge drink. According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), binge drinking means:

  • having 5 or more drinks in about 2 hours for men
  • having 4 or more drinks in about 2 hours for women

Your BAC may also rise quickly and cause a blackout if you drink alcohol on an empty stomach. When you don’t have food in your stomach, your bloodstream absorbs alcohol more rapidly.

Who’s At Risk Of Alcohol Blackouts?

Anyone can experience an alcohol blackout, regardless of age or gender. However, women generally face a greater risk of alcohol blackouts than men. That’s because women typically have less water in their bodies, which makes their BAC levels rise more quickly. 

You also face a higher risk of blackouts if you have a brain injury or a history of alcohol addiction (also called alcohol use disorder).

Finally, even if you don’t have a high BAC, you may experience a blackout if you drink large amounts of alcohol while taking benzodiazepines or barbiturates. That’s because these drugs act similarly to alcohol. 

Dangers Of Alcohol Blackouts

Blackouts occur when you drink too much alcohol. Thus, they pose the same short-term and long-term risks as unhealthy drinking habits and excessive alcohol consumption. 

Short-Term Risks

During an alcohol-related blackout, your decision-making skills will likely suffer. You might engage in risky behaviors you normally avoid, such as:

  • driving while drunk, which can cause serious injuries and death
  • fighting, which can cause serious injuries, legal problems, and damaged relationships
  • having unprotected sex, which can cause sexually transmitted diseases and unwanted pregnancy
  • spending too much money, which can cause financial problems
  • stealing or other illegal activities, which can cause legal problems

You may also trust people you usually wouldn’t and end up in dangerous situations. 

In addition, because excessive alcohol use impairs your coordination, you may slip, fall, or have similar accidents. 

Long-Term Risks

With frequent alcoholic blackouts, you likely face a high risk of alcohol addiction. This disease makes you feel unable to control your alcohol consumption despite negative consequences. Addiction and long-term heavy drinking can lead to various health problems, including:

  • alcohol poisoning (also called alcohol overdose)
  • depression
  • liver disease
  • high blood pressure, heart disease, and/or stroke
  • certain cancers, including cancer of the liver, colon, breast, esophagus, mouth, and throat
  • brain shrinkage
  • chronic memory problems
  • fetal alcohol syndrome (FAS) and/or sudden infant death syndrome (SIDS) if you drink alcohol while pregnant

Dependence & Withdrawal

Alcohol addiction also causes alcohol dependence. That means your body starts relying on the drug to function. If you stop drinking, you may experience alcohol withdrawal symptoms

Some people only have mild symptoms, such as anxiety, irritability, and trouble sleeping. Others experience more serious symptoms like confusion, hallucinations, and seizures. 

Blackouts don’t always indicate alcohol abuse or addiction. However, if you’ve been experiencing them, you should talk to your health care provider. They can help you determine whether you have a drinking problem and need treatment. 

To learn about treatment options for alcohol abuse or addiction, please contact an Ark Behavioral Health specialist. We provide a variety of substance abuse and addiction treatment services, including medical detox, mental health counseling, and aftercare planning. 

Written by Ark Behavioral Health Editorial Team
This page does not provide medical advice.

National Institute on Alcohol Abuse and Alcoholism - Drinking Levels Defined
National Institute on Alcohol Abuse and Alcoholism - Interrupted Memories: Alcohol-Induced Blackouts
U.S. National Library of Medicine - Alcohol-Induced Blackout

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