Blackouts: Causes, Side Effects, and Prevention

Alcohol impairs your ability to walk, speak, react, and remember events. It also lowers inhibition, hinders impulse control, and affects decision-making. A person can experience alcohol use abuse and depression a blackout at any BAC level, but it is most common when their BAC reaches 0.15% or higher. However, they are still as susceptible to blackouts if they keep on drinking.

During the blackout, the drinker tends to behave in ways that those around them read as merely being drunk. Their behaviors may be bolder or more out of character than seen when drinking in general, but often not to the point that those around them suspect that anything is wrong. Blackouts are not necessarily a sign of alcohol use disorder, but experiencing even one is a reason for concern and should prompt people to consider their relationship with alcohol and talk to their health care provider about their drinking. Complete amnesia, often spanning hours, is known as an “en bloc” blackout.

They explored the prevalence and correlates of this type of drinking behavior in 307 incoming freshman who reported consuming alcohol over the past 30 days. Nearly 77% of the incoming freshmen reported drinking alcohol in a pre-meditated, intentional manner with the goal of becoming intoxicated. Compared to those who did not drink to get drunk, individuals who reported drinking to get drunk were more likely to experience an alcohol-induced blackout. Further, consistent compare sober houses with the prepartying and drinking games studies described previously (LaBrie et al., 2011; Ray et al., 2014; Wahl et al., 2013), individuals who reported drinking to get drunk were also more likely to have prepartied and participated in drinking games. Although alcohol-induced blackouts were previously thought to occur only in individuals who were alcohol dependent (Jellinek, 1946), we now know that blackouts are quite common among healthy young adults.

Study Characteristics

This may be due to the physiological differences that affect alcohol distribution and metabolism. When drinking gets out of control, and as a person moves closer to addiction, certain behavioral signs may point to an alcohol use disorder. A person may hide alcohol and lie about their drinking habits during this time or become defensive when asked about their drinking. First, drinking to the point of blacking out means drinking heavily, which in itself has consequences. The drinker may experience headaches, vomiting, and even bloodshot eyes after alcohol.

1. Using data from a longitudinal study of college students, Marino and Fromme (2015) explored whether maternal or paternal family history of problematic alcohol use were better predictors than a general measure of overall family history on the likelihood of experiencing an alcohol-induced blackout.
2. Alcohol is dehydrating by nature, so making sure you’re drinking plenty of water and staying hydrated is important.
3. Although alcohol-induced blackouts were previously thought to occur only in individuals who were alcohol dependent (Jellinek, 1946), we now know that blackouts are quite common among healthy young adults.
4. Blackouts are caused by high levels of alcohol consumption, which can impair the brain’s ability to function properly.
5. Blackouts are not necessarily a sign of alcohol use disorder, but experiencing even one is a reason for concern and should prompt people to consider their relationship with alcohol and talk to their health care provider about their drinking.
6. It may also be referred to as “alcohol-induced amnesia.” Want to know what causes a drunk blackout?

So-called blackouts and brownouts can lead to temporary and even permanent memory loss. Not to mention, they can put you in danger of serious harm in the moment when alcohol and weed you’re not quite sure of your surroundings or what’s happening. A blackout ends when your body finally absorbs the alcohol and your brain can make memories again.

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A blackout ends when your body has absorbed the alcohol you consumed and your brain is able to make memories again. How much alcohol or substance use is needed to cause a blackout varies based on a person’s height, weight, sensitivity and assigned sex at birth. “Anything that causes damage to the brain, whether temporary or permanent, can cause memory loss if the damage is in the right spot,” states Dr. Streem. According to the National Institute on Alcohol Abuse and Alcoholism, alcohol delays signals in the brain that control the gag reflex and other autonomic responses. A person who has blacked out or overdosed on alcohol could throw up while sleeping due to the loss of reflex control.

The graph represents published articles and reviews published in English and includes both animal and human studies with the terms “blackout” and “alcohol” in the title, abstract, and/or keyword. One study estimated that the odds of experiencing a blackout is about 50% when blood alcohol content reaches 0.22 percent. You may not have any memory of the time that’s passed when your blood alcohol content is above that threshold. Psychologically, blackouts can result in feelings of depression or anxiety regarding alcohol use and lost memories. As long as excessive drinking continues, these immediate symptoms may extend into chronic mental health conditions.

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Given the potential impact of these findings on prevention and intervention programs, additional research examining genetic and environmental factors contributing to alcohol-induced blackouts is needed. A total of 26 publications met the criteria to be included in the review (see Table 1 for study details). Fifteen studies examined prevalence and/or predictors of alcohol-induced blackouts. Six publications described consequences of alcohol-induced blackouts, and five studies explored potential cognitive and neurobiological mechanisms underlying alcohol-induced blackouts.

Behavioral genetic research suggests that there is a heritable component to experiencing alcohol-induced blackouts (Luczak et al., 2006; Nelson et al., 2004; Slutske et al., 1999). Two recent studies explored genetic influences by examining the potential effects of family history of alcohol problems on blackout occurrence (LaBrie et al., 2011; Marino and Fromme, 2015). In a study of 2,546 college students, LaBrie and colleagues (2011) found that a family history of alcohol problems increased the likelihood of blacking out.

Blackouts and Your Brain: How To Avoid Memory Loss

This means that even after a blackout occurs, you can continue to experience memory loss and other difficulties recalling memories. Many people believe it just takes the right type of cajoling to coax back memories lost when blackout drunk. The hippocampus, responsible for forming long-term memories, shuts down entirely due to the chemical disruption from alcohol. Studies have shown that young adults under the age of 25 are particularly vulnerable to experiencing blackouts.

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To better understand alcohol-induced memory loss, here are the alcohol blackout facts to know. There are two types of blackouts; they are defined by the severity of the memory impairment. The most common type is called a “fragmentary blackout” and is characterized by spotty memories for events, with “islands” of memories separated by missing periods of time in between. If you’re experiencing a blackout or brownout, you’re at higher risk for falling, injury and unwanted or unsafe sexual experiences. A person who is blacked out may also throw up while sleeping, which could lead to an increased risk of choking or suffocating. Number of published journal articles or reviews that evaluate alcohol-induced blackouts per year (1985 to 2015).

As such, future research should use alternative methodologies to better understand the phenomenology of alcohol-induced blackouts. For example, information might be obtained from a research observer, posing as a confederate, who is not drinking but is present at the drinking event. Also, because short-term memory remains intact, use of ecological momentary assessment with smart phones might also be useful for gathering information about the drinker’s experiences while he or she is in a blackout state. Subsequent interviews could then determine what aspects of those events were remembered and whether they were remembered in the same way that they were reported during the drinking event.

Despite the increase in research on and our understanding of alcohol-induced blackouts, additional rigorous research is still needed. Studies examining potential genetic and environmental influences, as well as their interactions, are clearly warranted given recent research findings of Marino and Fromme (2015). Sex differences in alcohol-induced blackouts are another area in need of study. Although previous research indicates that women are more vulnerable to alcohol-induced blackouts due to the effect of sex differences in pharmacokinetics and body composition on alcohol bioavailability (Rose and Grant, 2010), the influence of biological sex on alcohol-induced blackouts are inconsistent. These inconsistent findings could be due in part to methodological differences across research studies and assessment of alcohol-induced blackouts, and future studies should address this issue.

Gateway Foundation is an alcohol addiction treatment center in Illinois, dedicated to helping people of all backgrounds learn to live life without drinking. We understand that every person arrives at addiction differently, and so we treat each individual according to their unique needs and circumstances. With a personalized treatment, you or someone you care about can take the necessary steps to understand and overcome alcohol addiction through residential, partial hospitalization or outpatient programs, depending on your needs.