Maybe you’ve heard stories of people blacking out after drinking alcohol, or perhaps you’ve blacked out yourself in the past. But what causes people to black out? If you drink or know someone who does, this is an important question to ask. Understanding the actual physiological event that occurs when someone blacks out can help you understand the dangers involved.
Blacking out after drinking is more than just getting very intoxicated and passing out. Passing out occurs when you lose consciousness or fall asleep after consuming too much beer, liquor or other spirits. Conversely, the drinker is awake during a blackout, but the drinker’s brain is not creating memories of their actions or what’s going on around them.
The National Institute on Alcohol Abuse and Alcoholism (NIAAA) characterizes alcohol-related blackouts as leaving gaps in the drinker’s memory regarding events that occurred during the time the drinker was intoxicated. These gaps occur due to an effect on the brain’s hippocampus, which is responsible for memory consolidation. Drinking to excess blocks the brain from transferring memories from short-term to long-term storage.
Blacking Out: What Your Body Is Saying
People who drink often wake up the next day with vague memories of what occurred the night before. Looking back at the night’s events, things may seem foggy or unclear. If this has happened to you, you’re not alone. Drinking enough to cause a blackout is practically a rite of passage in popular culture. In fact, up to 40 percent of college students report having blacked out while drinking. Still, blacking out is scary from a physiological point of view.
Researchers say blood alcohol concentrations (BACs) of 0.16 or more are closely associated with blacking out. This BAC level comes with significant impairment of a person’s cognitive abilities, including decision-making, judgment, attention and impulse control. Blackouts are even more pronounced and occur at lower BACs for drinkers who take antianxiety or sleep medicines.
Blackouts are also more likely to happen when someone drinks a lot of alcohol fast or drinks on an empty stomach, which results in a rapid rise in BACs. The less the drinker weighs, the faster the rise in BACs in the body, which helps explain why females are more prone to blacking out after/while drinking than male drinkers.
Two Types of Blackouts
The NIAAA reports two types of blackouts caused by alcohol consumption. The first of these is the fragmentary blackout. The drinker has spotty memories of events that occurred while they were inebriated, with time missing in between vague remembrances. Some people refer to this type of blackout as a brownout or grayout.
An “en bloc” blackout is the second type. This blackout is the most severe of the two and involves complete loss of memory for hours while drinking. During this type of blackout, no memories are formed, so none can be recovered. In the drinker’s mind, it’s as if the events never existed.
Negative Consequences Associated with Blackouts
Research among young adults underscores the fact that blackouts, while not necessarily a surefire sign of disordered drinking, are cause for concern. Blackouts among study subjects were closely associated with missing classes or work, sustaining injuries, getting bad grades and being arrested. Moreover, the NIAAA warns that heavy alcohol use and binge drinking can heighten a person’s risk of alcohol use disorder.
Levels of Drunkenness
BACs are used to determine to measure a person’s level of drunkenness. These levels exist on a predictable path based on the number of drinks consumed. The Centers for Disease Control (CDC) notes that a standard drink is a 12-ounce beer, an 8-ounce serving of malt liquor, 5 ounces of wine or 1.5 ounces of 80-proof liquor such as whiskey or vodka. A breakdown of levels of drunkenness by BAC follows.
- 0.01 to 0.05 BAC. Generally, one or fewer drinks in an hour lead to a BAC of less than 0.05. Most drinkers feel pretty much normal at this point.
- 0.03 to 0.12 BAC. This second stage of drunkenness is characterized by the drinker’s euphoria. People at this level are usually deemed “tipsy.” For women, one to two drinks in an hour and for men, two to three drinks is common. Drinkers feel chatty and self-assured. Reaction times are lessened, and inhibitions follow suit. Notably, the legal BAC limit is just 0.08, which falls in this tipsy stage.
- 0.09 to 0.25 BAC. After women drink two to four drinks within an hour or men drink three to five, they are officially drunk. It’s at this stage that folks may have trouble remembering things and using good judgment. Loss of balance, blurry vision, tiredness, drowsiness and emotional instability are common.
- 0.18 to 0.30 BAC. Once a woman drinks four drinks or a man drinks five drinks in an hour, BACs may surge as high as 0.30. Blackouts may occur without the loss of consciousness. Drinkers may also fade in and out of a conscious state. Standing and walking is difficult, and drinkers may be impervious to pain, which increases their risk of becoming injured. Emotional outbursts are commonplace.
- 0.25 to 0.40 BAC. Stupor characterizes this stage of drunkenness. The drinker doesn’t respond to anything around them. They can’t walk or even stand. They may lose control of their bowels or even seize. Breathing is abnormal. Because the gag reflex stops working correctly, the drinker may vomit and choke on it, which can be deadly.
- 0.35 to 0.45 BAC. People whose BACs reach this level may go into a coma since their bodily functions have slowed significantly.
- 0.45 or greater BAC. Death is likely once BACs reach this level.
Do You Need Help?
According to the NIAAA, moderate consumption of alcohol means limiting intake to one drink or less a day for women and two drinks a day or less for men. The organization defines binge drinking as a drinking pattern that raises BAC to 0.08 or more regularly. It goes on to say that heavy drinking is defined as women having seven or more drinks per week and men having 14 or more drinks per week. Another definition is drinking on five or more days each month.
If you or someone you love struggles with binge drinking or has a drinking problem, there’s hope. Reaching out for help is not a sign of weakness—it’s a sign of strength. Call our compassionate, nonjudgmental team of counselors to get started on your journey toward recovery, health and happiness. Contact us at (833) 596-3502.