Alcohol makes people more likely to cheat primarily because it impairs the part of the brain responsible for judgment, self-control, and long-term thinking. Roughly 1 in 10 people in one large survey admitted to cheating on a partner while drinking. But the explanation isn’t as simple as “drunk people can’t help themselves.” The real answer involves a combination of brain chemistry, narrowed attention, pre-existing beliefs about alcohol, and personality traits that were there long before the first drink.
What Alcohol Does to Your Brain’s Braking System
The prefrontal cortex is the region of your brain that weighs consequences, controls impulses, and keeps your behavior aligned with your goals and values. It’s essentially your internal braking system. Alcohol suppresses activity in this region in a dose-dependent way, meaning the more you drink, the worse it functions.
The impairment starts earlier than most people realize. At a blood alcohol concentration (BAC) of just .02, roughly one standard drink for many people, judgment begins to slip. By .05, inhibitions start to loosen. At .08, the legal driving limit in most states, self-control, reasoning, and memory are all measurably impaired. So by the time someone feels “buzzed,” their ability to pump the brakes on a bad decision is already degraded. The prefrontal cortex doesn’t shut off like a light switch. It dims gradually, and each drink turns it down a little further.
How Alcohol Narrows Your Focus
One of the most well-supported explanations in psychology is called Alcohol Myopia Theory. The idea is straightforward: alcohol shrinks your attentional spotlight. When you’re sober, you can hold multiple things in mind at once. You notice the attractive person flirting with you, but you also think about your partner at home, the consequences of getting caught, and your own values. Alcohol collapses that wide-angle view into a narrow beam pointed at whatever is right in front of you.
This means the most immediate, salient cue in your environment dominates your thinking. If that cue is physical attraction or the excitement of someone’s attention, those feelings flood the foreground while thoughts about your relationship, your commitments, and tomorrow’s guilt fade into the background. It’s not that intoxicated people don’t care about their partners. It’s that their brains temporarily lose the capacity to hold those distant, abstract concerns alongside the vivid, present ones.
There’s an important nuance here. The theory specifies that alcohol only changes behavior in high-conflict situations, where the pull toward doing something and the reasons not to are both strong. If someone has zero attraction to another person, alcohol won’t create it. And if someone has no real commitment holding them back, they might cheat sober just as easily. Alcohol tips the scales specifically when someone is genuinely torn, pushing them toward whichever impulse is most immediate.
The Role of What You Believe Alcohol Does
People don’t just respond to alcohol’s chemical effects. They also respond to what they expect alcohol to do. Psychologists call these alcohol outcome expectancies, and they form through years of watching how people around you behave when they drink, how movies and TV portray drunkenness, and your own past experiences.
If you grew up absorbing the message that alcohol “makes people lose control” or “brings out hidden desires,” you’re more likely to behave in ways that match those beliefs when you drink. In a sense, the cultural script gives people a framework, and sometimes an excuse, for acting on impulses they might otherwise suppress. Research in naturalistic bar settings has found that people’s intoxicated behavior generally mirrors the expectations they held before drinking. What you believe the alcohol will do to you shapes what it actually does, at least behaviorally.
This also explains why some people use alcohol as a convenient shield after the fact. Saying “I was drunk” can feel like a ready-made explanation that shifts responsibility away from personal choice. The belief that alcohol removes agency becomes self-reinforcing: people expect to lose control, behave as though they’ve lost control, and then point to the alcohol as the cause.
Personality Traits That Raise the Risk
Not everyone who gets drunk cheats, which means alcohol alone isn’t the full story. Research comparing people who have cheated with those who haven’t has found consistent personality differences. People who report infidelity tend to score higher on extraversion and openness to new experiences, and lower on conscientiousness and agreeableness. They also tend to score higher on neuroticism.
Think about what that looks like in practice. Someone who is naturally more impulsive, more drawn to novelty, more socially outgoing, and less inclined toward rule-following is already closer to the line before they pick up a drink. Alcohol doesn’t create a new personality. It amplifies the one that’s already there by stripping away the self-regulation that normally keeps those traits in check. A highly conscientious person who gets drunk might send a regrettable text to an ex. A person low in conscientiousness and agreeableness who gets drunk faces a steeper slope toward crossing a serious boundary.
Blackouts Complicate Everything
At higher levels of intoxication, alcohol doesn’t just impair judgment. It stops the brain from forming memories entirely. Alcohol-induced blackouts are gaps in memory that occur because the hippocampus, the brain’s memory-recording center, gets temporarily shut down. During a blackout, a person is still awake, still talking, still making choices. But their brain isn’t storing any of it.
The most common type is a fragmentary blackout, where someone remembers scattered pieces of the night with missing stretches in between. The more severe form, called an en bloc blackout, can erase hours completely. Those memories don’t come back because they were never created in the first place.
This creates a painful situation for both partners. The person who cheated may genuinely not remember doing it, which can look like denial or dishonesty. The lack of memory doesn’t undo the act, but it does mean the person was operating at a level of impairment where even basic cognitive functions like memory formation had failed. It also makes it harder for the person to understand their own behavior, process what happened, or identify the triggers that led to it.
Who It Happens to Most
Survey data reveals some patterns that might surprise you. Women reported being only slightly more likely than men to cheat while drinking. People who were separated or divorced were roughly twice as likely as those in committed relationships to report alcohol-related infidelity, with more than 1 in 5 in that group saying it had happened. Geography played a role too: people in the upper Midwest were most likely to report it, while those on the West Coast and in the South were least likely.
Perhaps the most unexpected finding: people aged 60 and older were the most likely age group to report cheating on a partner while drinking. This may reflect a lifetime of accumulated drinking experiences, different social norms, or simply a greater willingness to be honest in surveys. Whatever the cause, it challenges the assumption that alcohol-fueled infidelity is mainly a young person’s problem.
Why “I Was Drunk” Isn’t the Whole Answer
Alcohol creates conditions that make cheating more likely. It weakens impulse control, narrows attention to what feels good right now, and in extreme cases erases the memory of what happened. But it works on a foundation that was already there: the personality traits, the relationship dissatisfaction, the attraction, the expectations about what drinking “does” to people.
The most accurate way to understand it is that alcohol lowers the threshold for acting on desires that already exist. It doesn’t implant new ones. Someone with strong boundaries and high relationship satisfaction can get very drunk and still not cheat, because even a diminished prefrontal cortex has enough to work with. Someone who is already unhappy, already attracted to someone else, and already prone to impulsive decisions faces a much thinner line, and alcohol erases what little of that line remains.