Alcohol Blackouts: What Happens in the Brain

An alcohol-induced blackout is a troubling type of memory loss that occurs when your blood alcohol level spikes and impairs how the brain works.

What You’ll Learn:

• Why blackouts happen from drinking alcohol.

• How much alcohol causes a blackout.

• Who is most likely to experience alcohol-induced blackouts.

• The effects on the brain during a blackout.

• The dangers related to alcohol blackouts.

• Why blackouts can increase openness to intervention.

Have you ever experienced an alcohol-induced blackout? Getting blackout drunk doesn’t mean you pass out from drinking. In fact, you can be active for hours in an alcohol blackout state.

Alcohol blackouts are actually about memory loss. You wake up the next day after heavily drinking and can’t remember much of anything after a certain point. While it doesn’t happen to everyone and can happen to varying degrees, alcohol blackouts are fairly common.

And they can be very dangerous.

What Causes Alcohol Blackouts

For some time, it was believed that blackout drunkenness wasn’t a common physical effect of alcohol consumption. After years of research, medical experts now have a better understanding of why alcohol blackouts happen and who is most susceptible.

It was a series of experiments in the 1960s that started the scientific exploration into alcohol blackouts. And these were experiments that couldn’t be done today because study participants were given large quantities of alcohol to induce a blackout state.

While those experiments were somewhat dangerous, they did reveal some key information about what happens during blackouts and what causes them. Researcher Donald Goodwin determined at the time that roughly 60% of the participants experienced blackouts.

Another noteworthy factor is that there can be total blackouts and fragmentary blackouts where you still remember bits and pieces of a drinking episode. The initial research from the 1960s showed that short-term memory can work to a certain degree during blackouts, but long-term memory is seriously impaired.

The cause for the blackouts is heavy drinking. Later research using mice rather than human test subjects revealed that in smaller doses brain cells can continue functioning. But significant alcohol intake can shut brain cells down completely.

While it can vary, alcohol-induced blackouts are more likely when blood alcohol level reaches .16%. That’s twice the legal limit. And if you reach .20% blood alcohol level you’re in the total blackout zone.

But there are other factors that play a role in blackouts. The quicker you drink, the quicker your blood alcohol level will spike and a blackout is more likely. Sleep deprivation and drinking on an empty stomach also increase the likelihood of an alcohol blackout.

It wasn’t until 2016 that researchers found out why some people didn’t experience a blackout even if they consumed large quantities of alcohol. How often a person binge drinks also plays a role.

Alcohol can break down the blood brain barrier over time. This allows more alcohol to get through to brain cells, which makes blackouts happen more frequently.

There’s also a difference between the sexes. Women are notably more likely to experience blackouts. This is because they have a lower body weight and higher percentage of body fat compared to men. There’s less water to dilute the alcohol so women’s blood alcohol concentration can spike quicker.

There’s also a possible genetic link to who experiences alcohol blackouts. A variety of different studies have analyzed this point from multiple angles. One study looked at the drinking habits of mothers and their offspring’s blackout experiences. Another studied 1,000+ sets of twins. Yet another study examined impulse control in 12-21 year olds before and after they started drinking alcohol.

In all these studies there was a connection between genetics and blackouts. So it appears some people are genetically predisposed to having alcohol blackouts.

What Happens to the Brain During Blackouts

One of the most bizarre things about alcohol blackouts is that the person can seem coherent or even sober during it. They might not remember a thing the next day, but they could have done a lot during that time and may even remember things for a short period while drinking. However, minutes later what just happened is forgotten and by the next morning it’s all a blur at best.

It’s well known that alcohol suppresses neural activity. During blackouts the brain temporarily can’t form new memories. The brain can’t encode information properly so there are gaps in a person’s memory.

It’s now believed that blackouts impair the hippocampus, a part of the brain that is vital for forming new memories. When the hippocampus is shut down it’s impossible to make episodic memories. These are memories connected to a specific time and place.

The bad news is the memories of what happened are gone forever and won’t be remembered later. Because short-term memory is impaired, the memories don’t ever make it to long-term storage in the brain.

Also affected are the frontal lobe and amygdala. This is particularly problematic given that the frontal lobe controls reasoning and the amygdala alerts us to danger. During a blackout episode you can do very risky things and not even remember it.

The Dangers of Getting Blackout Drunk

As you can imagine, alcohol-induced blackouts can be extremely dangerous in many ways, even compared to non-blackout binge drinking episodes. During blackout drinking bouts a person is more likely to:

• Engage in risky sexual behavior

• Be victimized

• Drive while inebriated

• Sustain an alcohol-related injury

• Overdose on illegal substances

• Get into physical altercations

Repeated blackouts have additional risks, such as:

• Structural changes to the brain

• Smaller hippocampus

• Impaired cognitive function

• Reduced memory formation

Even worse is that because memory is impaired, someone who has blacked out isn’t considered a reliable source. So if you are victimized in any way, any complaints may not be taken seriously.

The One Upside to Alcohol-Induced Blackouts is Being More Open to Intervention

Having a blackout episode can be very troubling and unsettling to some. So much so, many people are more open to the idea of reducing alcohol after it happens. Addiction psychologists have found that blackouts are a sort of wakeup call that makes people more receptive to intervention.

Doctors also use questions about blackouts on screening surveys to identify people who have alcohol use disorder and need treatment. Blackouts are an indicator of binge drinking and more significant problems related to alcohol use.

If you’ve experienced blackouts from alcohol and want to reduce your risk of having another, naltrexone medication can be of benefit. Naltrexone’s effect on the brain’s reward system when alcohol is consumed helps to reduce the urge to binge drink, which lowers the chance of a blackout.

To find out if prescription naltrexone could be a solution and get professional guidance based on your drinking habits, take the Alcohol Use assessment. It’s the first step in making a positive change that will protect your brain health by reducing alcohol use.