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The National Institute on Alcohol Abuse and Alcoholism defines alcohol blackouts as: gaps in a person's memory for events that occurred while intoxicated.
These gaps happen when enough alcohol is consumed to block the transfer of memories from short-term to long-term storage. The transfer of memories, called memory consolidation, occurs in a part of the brain called the hippocampus.
A person experiencing an alcoholic blackout may appear to be functioning fairly normally, but may have no subsequent recollection of several hours to days worth of events during the blackout. They may not even appear to have been very intoxicated at the time.
In addition to impacting memory, getting blackout drunk can impair balance, motor coordination, decision making, and many other body functions.
Heavy alcohol use can damage the hippocampus and the ends of neurons, called dendrites. Frequent blackouts can impact short- and long-term memory and lead to memory loss.
There are two different types of blackouts:
For young adults, getting to the point of 'blackout' while drinking alcohol is common. In a study of over 1,000 college students, more than two-thirds – 66.4% – reported experiencing at least one blackout.
Blackouts are almost always associated with binge drinking, a pattern of drinking that increases a person's BAC to 0.08 percent or higher. Blackouts usually begin at blood alcohol concentrations (BACs) of about 0.16 percent and higher.
This increased blood alcohol level typically occurs after four drinks for women and five drinks for men — in about 2 hours. This level of blood alcohol content causes a significant cognitive ability impairment that makes blackouts especially dangerous.
Blackouts can also occur at much lower blood alcohol levels in people who drink alcohol and take sleep and anti-anxiety medications.
Women have a much greater risk of experiencing blackouts than men while participating in heavy drinking.
It can be hard to recognize when you or a friend are in danger of blacking out. However, there are some signs that people may be reaching a dangerous level of intoxication.
Keep in mind that many factors affect your body's response to alcohol. Body size, alcohol tolerance, and whether you ate earlier are a few of the most significant factors. This will affect the number of drinks it takes to reach these stages.
Here are some symptoms of progressing drunkenness, sourced from the NHS:
(These numbers are based on a male of average size and average tolerance.)
1 to 2 drinks
4 to 6 drinks
8 to 9 drinks
10 to 12 drinks
12 or more drinks
During a blackout, a person is awake but their brain is not creating new memories.
It isn't always apparent if someone is in a blackout. Anything someone can do while drunk, they can do while blacked out – they just won't remember it the next day.
During a blackout, a person will remember events that happened before their BAC reached very high levels. People who were blacked out can carry on conversations and recall stories from earlier in the evening while intoxicated.
In addition, depending on how much the person drank, they can quickly transition from a blackout to losing consciousness or alcohol overdose.
Someone who is blacked out may have the following symptoms of alcohol intoxication:
Blackouts happen when alcohol enters the bloodstream quickly, causing the BAC to rise rapidly. A blackout is more likely someone drinks on an empty stomach or consumes excessive amounts of alcohol in a short amount of time.
Women are at an increased risk of blacking out. On average, women weigh less than males and, pound for pound, have less water in their bodies. They tend to reach higher peak BAC levels than males with each drink and do so more quickly.
Young adults and college students tend to binge drink more often than adults. They also drink more when they do binge drink. One study surveyed 772 college students to learn about their drinking habits. It found that 51 percent had blacked out at some point in their life.
Students that blacked out often experienced adverse effects including:
Blacking out while drinking usually happens accidentally. If you've experienced blacking out, here are some tips to consider the next time you're drinking:
If you think someone is passed out, check-in by trying to wake them up by lightly shaking them or calling their name. You should ensure they're not in a dangerous place where someone could harm or take advantage of them.
Check if they've lost consciousness from the alcohol or if they're merely sleeping. If the person is unresponsive, or if their breathing is very shallow, they're throwing up, or they're cold and blue, they may have alcohol poisoning, in which case you should call 911.
If the person is acting aggressively, or has had a fall or significant injury, you should call 911 immediately. Any time you are worried, take that person to an ER. Seek immediate medical care if you believe a person may have alcohol poisoning or is suffering from a drug overdose.
Blacking out while drinking alcohol can cause many immediate consequences. Blackouts directly increase your chances of risky behavior.
This can lead to any of the following short-term effects:
Experiencing a single blackout does not necessarily indicate that a person has a drinking problem. However, blacking out often increases the risk of developing an alcohol use disorder (AUD) or other health problems. If you experience blackouts regularly, you may have a drinking problem.
Long-term effects of alcohol use disorder can be severe and life-threatening, including:
If you or someone you know is addicted to alcohol, you should seek help. There are many types of addiction treatment available for those suffering from an alcohol use disorder.
Inpatient treatment takes place at a licensed residential treatment center.
These programs provide 24/7 comprehensive, structured care. You'll live in safe, substance-free housing and have access to medical monitoring. The first step of an inpatient program is detoxification. Then behavioral therapy and other services are introduced. These programs typically last 30, 60, or 90 days, sometimes longer.
Most programs help set up your aftercare once you complete the inpatient portion of your treatment.
Partial hospitalization programs (PHP) provide similar services to intensive outpatient programs (IOPs). These include medical services, behavioral therapy, and support groups, along with other customized therapies. However, in a PHP you return home to sleep.
Some services provide food and transportation, but services vary by program. PHPs accept new patients as well as people who have completed an inpatient program and still need intensive treatment.
Outpatient treatment is less intensive than inpatient or partial hospitalization programs.
These programs organize your treatment session based on your schedule. The goal of outpatient treatment is to provide therapy, education, and support in a flexible environment. They are best for people who have a high motivation to recover and cannot leave their responsibilities at home, work, or school. Outpatient programs are often part of aftercare programs once you complete an inpatient or PHP program.
Sometimes, medications may be used in alcohol addiction treatment.
Some medicines can help reduce the negative side effects of detoxification and withdrawal. Others can help you reduce cravings and normalize body functions.
Disulfiram (Antabuse), acamprosate (Campral), and naltrexone are the most common medications used to treat AUD. When combined with other evidence-based therapies (such as cognitive behavioral therapy), MAT can help prevent relapse and increase your chance of recovery.
Support groups such as Alcoholics Anonymous and SMART Recovery are open to anyone with a substance abuse problem.
They are peer-led organizations dedicated to helping each other remain sober. They can be the first step towards recovery or part of a long-term aftercare plan.
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