10 reasons why people act out of character

Prairie dog wearing a blue hat, singing into a microphone

Estimated reading time: 7 minutes

Other people are baffling a lot of the time. Of course, some people are always erratic. You never know what they’re going to do. But even steady people act out of character at times. What makes you or others act out so bizarrely?

Here are some ideas.

1 Lack of assertiveness

Sometimes you hold back from saying what you really think. You go along with others even if you don’t agree with them. Finally after much discomfort, you make a stand.

You do and say what you really believe. But unfortunately you take others by surprise. What you say now doesn’t match what you said before.

John and Michelle

John wants to work in another city. However, his wife Michelle loves her current job and doesn’t want to move. So she hides her true feelings and claims she supports John. Secretly however, she hopes he won’t get the new job.

When he does, she’s agitated and angry, and they argue for hours. John’s completely taken aback by her reaction, the reverse of previous behaviour. She’s acted out of character due not wanting to upset John.

Michelle would benefit from learning how to be more assertive.

2 Previous history

Perhaps you’ve been badly treated in some way in the past. Now you may sometimes react strongly in some situations. And you may not really be aware of what triggers you to act in this way.


When Anna was young, she often saw her father hit her mother. Now she’s highly vigilant for any hint of violence.

Recently she was on a train with a teenage couple who were down the other end of the carriage. They were joking, teasing and scuffling with each other. Then suddenly the girl squealed loudly.

Terrified, Anna was certain the boy was hurting the girl. Normally shy, she was ready to leap up and yell at him to stop.

However, no-one else seemed at all worried. So shaking, she sank back in her seat. After a few moments, she realised the boy was tickling the girl.

Past experiences had led Anna to misinterpret the situation. If possible, she now checks out situations more fully before reacting.

3 Stress

Stress from work, relationship or financial difficulties, and daily hassles can make people temporarily act out of character.

When you’re overwhelmed, empathy for others evaporates. Your world narrows to your own concerns. You just don’t have the energy to care about anything else, even if you did before.


James is usually a kind and considerate manager. He believes in letting staff learn from their mistakes. However, lately he’s been irritable with his workers.

After reprimanding a young man at the weekly meeting, he realises his behaviour is out of line.

Unusually for him, his emotions are all over the place. He’s been overworking, and eating and sleeping badly. He’s also worried about impossible targets his team has to meet. Unless he looks after himself more, he’s in danger of burnout.

4 Alcohol and drugs

Alcohol loosens restraints we put on our behaviour. Under its influence we can act out of character. End result? Major embarrassment.


Heather’s a kind woman who works with Josie, a difficult colleague. Yesterday, Heather hadn’t eaten for hours before going to work’s happy hour. Within a short time, she downed several drinks and was soon unusually merry.

Then she astonished everyone by reeling off a string of Josie’s irritating habits.

The next day, Heather was mortified. Luckily, she and Josie cleared the air with the help of their manager. And Heather vowed never to drink on an empty stomach again.

5 Peer group pressure

Not many of us are able to withstand strong peer group pressure when we’re feeling unsure of ourselves. Children and teens in particular often fear ridicule if they don’t conform to some mysterious code of behaviour set by the “popular” kids. 

Even adults can be swept up by a sort of emotional contagion in the heat of the moment. They may be away from their usual environment, with unfamiliar people. In an effort to feel part of the group, they may do things they’d never normally do. At the same time, they brush away the consequences of their actions. 

6 Worry or mood issues

When you’re feeling low, maintaining emotional balance can be hard. That’s when you may act erratically or out of character.

If you’re worried or down, you may be irritable and avoid others. You lose interest in activities that usually make you feel good.

Lack of confidence stops you taking on challenges. You can misinterpret other’s actions, and feel they’re against you.

Eating and sleeping habits seem to fall in a heap. And exercise is the last thing you feel like doing. In fact, the worse you feel, the less you do.

Ironically, the very things that are most helpful are the things you don’t want to do.

So fight against the urge to drop all those helpful habits. It doesn’t matter if you don’t enjoy them right now. Have faith that you will at some stage soon.

7 Medical conditions

Many people may not wish to tell others they’re not well. They may have a transient illness, back pain, or a chronic condition. In any case, their quality of life may be affected.

Pain can make people irritable, with little interest in others. People on diets can also feel irritable due to low blood sugar and hunger. In addition, restricting food intake makes their thinking fuzzy. Bladder infections can also make some elderly people seem confused.

So be aware that you may not have the full picture about someone. Their behaviour may be affected by factors you don’t know about.

8 Strong emotions

Most people know the craziness that appears when you’re infatuated. The most sensible person can act impulsively in the grip of passion. Their whole being is taken up with this powerful obsession. Normal behaviours are tossed to one side.

Other strong emotions

Other strong emotions such as jealousy, anger, or a desire for revenge can also make people act out of character.

Someone who’s been treated badly for years may suddenly wreak revenge. Or someone may sabotage a friend’s happiness in a fit of jealousy.

Anger at being thwarted

If you interrupt someone engrossed in activity, they may lash out. For instance, gamers are notoriously aggressive if their game is shut down. And how do you feel if someone switches off your favourite show?

Even mild people may lash out if they can’t get what they want. It’s really an adult-sized temper tantrum. People think in that moment they have the right to act any way they please. If this happens too often, they need to learn to combat angry thoughts. It helps if they’re aware of the harm done by that momentary spurt of anger.

Unfortunately others sometimes ignore the warning signs when someone shows intense anger frequently. They hope everything will work out without them intervening. However, consulting a trusted doctor may be a more effective option. That may lead to getting specialised help for the person.

9 Psychosis

Young people often don’t know marijuana can trigger psychosis. This can happen if they have a family history of mental illness, or a personal vulnerability.

Psychosis can cause someone to act out of character. People may sense things or people around them that others can’t. And they can respond as if what they’re hearing or seeing is real. They can wrongly believe others have betrayed or done them harm. They may also flee and hide from imagined persecutors.

Manic people may believe they’re important historical figures or celebrities. Or that they have special powers or abilities.

Any of these behaviours are cause for immediate alarm.

The difficulty is that the person firmly believes these experiences are real. So they often become agitated at any suggestion they need help.

Tread very softly, and let professionals handle the situation if you can. Contact a doctor or mental health services for advice and assistance without delay.

10 Dementia

Dementia may also cause people to act in unexpected ways. The onset can be slow, so warning signs aren’t always picked up.

However, the person may have trouble solving problems or making decisions. Eventually they can’t do tasks they’ve done all their lives, such as cooking a favourite recipe, managing their finances, or finding their way around their neighbourhood. They may also get anxious about little changes in their routines.

Their behaviour can also change in other, disconcerting ways. Normally quiet people may become loud and aggressive, courteous men may act inappropriately towards women, and others may accuse relatives of stealing from them.

Remember, the person doesn’t understand what’s happening. Getting angry with them may make them even more agitated.

So seek guidance from a doctor, and a support group if appropriate.

Behaviour has many causes

The above list of reasons why people act strangely isn’t complete. There are no doubt many other causes.

But it may help the next time someone you know acts out of character. Pause before getting annoyed or assuming they’re a bad person. You don’t know what’s going on in their lives.

They may be coping the best way they can. Perhaps you can give them the benefit of the doubt. And if you’re really worried, seek advice and help from qualified health professionals.

Most people act out of character occasionally. Make sure you’re aware of possible reasons before you jump to conclusions.

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