People who experience paranoia think that other people are trying to do them harm, even though there is no convincing evidence for that to be the case. Paranoia is the unfounded fear that something bad is going to happen, and that other people are responsible for this.

People who experience the symptoms of psychosis often have paranoid thoughts, which can be a frightening and disturbing experience. They may live in fear of being physically harmed, believe that nasty rumours are being spread about them, or believe that other people or organisations are plotting against them, or trying to control them – by tampering with their thoughts, for example. Sometimes, the person isn’t sure who is trying to harm them.

Back to top

Persecutory delusions

Mental health professionals call the most extreme versions of these paranoid thoughts ‘persecutory delusions’ and they are one of the most common symptoms of schizophrenia, though not everyone with schizophrenia will have them. These sorts of experiences can be accompanied by voices that say things to confirm people’s beliefs and fears.

Persecutory delusions are a symptom of paranoid schizophrenia, which is a 'sub-type' of schizophrenia. Sometimes, people who are given a diagnosis of paranoid schizophrenia may see themselves as being particularly important in some way, and may believe this is the reason why they are being persecuted. They may also experience auditory hallucinations, sometimes sinister whispering or laughter as well as voices that are mocking or threatening.

People may be given the less common diagnosis of 'delusional disorder' if they experience persecutory delusions but do not experience hallucinations.

Anyone who experiences persecutory delusions is likely to withdraw from other people to try to protect themselves, and to avoid situations where they may feel threatened. They will probably spend a lot of time by themselves, worrying about their fears. If someone believes that other people are intent on harming them, they start to interpret actions and events in a way that confirms their beliefs, rather than considering alternative explanations.

Back to top

Paranoia is not just a symptom of psychosis

Many people have ‘suspicious thoughts’ at some time or other. Most people have experienced the feeling that other people are talking about them, or laughing about them behind their back, or have been worried that a group of young people they are passing on a street corner could be dangerous and mean them harm. These feelings can be considered as mild, everyday forms of paranoid thinking.

Researchers think paranoid thoughts might be almost as common as depression or anxiety: they say one in four people have regular paranoid thoughts that influence the way they feel about other people and the safety of the world.

However, paranoid thoughts only become a problem if they stop people getting on with their everyday life because they are frightened of what might happen. They are similar to phobias – a fear of heights, or spiders, for example. Many people have such fears from time to time, but phobias only become problematic for a small number of individuals.

Back to top

Why do people become paranoid?

Researchers say our emotions have a big influence on how we interpret the actions of other people and events that are part of our lives.

When people are anxious, they are more likely to interpret events in a negative or fearful way, and they are more likely to expect bad things to happen to them.

Similarly, when people feel miserable, depressed or bad about themselves, they see themselves as vulnerable and are more likely to misinterpret people’s intentions towards them.

Being angry, or feeling different from other people, can also cause someone to misinterpret what’s going on. If someone believes they are special in some way, they may begin to believe other people are trying to undermine them.

Paranoid thoughts can also be triggered by what mental health professionals call ‘anomalous experiences’. ‘Anomalous’ means strange, unusual, or out of the ordinary – so experiences of this kind include hearing voices, for example, or seeing things that aren’t there. An anomalous experience might be feeling the world is slightly unreal, or that you are observing what is happening around you, as if you are watching a film rather than being part of it. Anomalous experiences can be caused by a traumatic event, by lack of sleep, by a bereavement, by drugs or alcohol, or by a mental illness.

Our minds will naturally try to make sense of these anomalous experiences, to try to work out what is going on – and one explanation is that whatever is happening is caused by other people. Hallucinations, such as hearing threatening voices, can be so real to the person who is experiencing them that it may be difficult to come up with a different explanation.

When people begin to feel unsafe, they become on guard, dwelling on their thoughts and worrying a lot about what might happen. The more people worry, the more likely they are to continue to think the worst. They can begin to jump to negative conclusions about everyday events and look for evidence to reinforce their fears, rather then evidence that can offer an alternative explanation.

Back to top

Sleep problems

Researchers think insomnia, or finding it really difficult to get to sleep, may be linked to feelings of paranoia.

Studies have shown that sleep problems, especially insomnia, are common in people who experience persecutory delusions. A study by researchers at the Institute of Psychiatry indicated that up to 60 per cent of people who experience persecutory delusions have had sleep difficulties. This is compared with around 30 per cent of the general population who experience disturbed sleep.

Lack of sleep can cause anxiety, worry, depression and ‘anomalous experiences’, all factors that can trigger and perpetuate paranoid thoughts.

Researchers think it is likely that improving sleep patterns may help lessen people’s feelings of paranoia.

Most people need seven or eight hours’ sleep a night. Your relative’s GP can advise on ways of improving sleep and there are self-help books available about strategies to combat insomnia. These strategies include taking exercise during the day, cutting out caffeine, alcohol and nicotine in the evenings, having a healthy snack before bedtime, having a relaxing routine in the evening before going to bed and only going to bed when properly tired.

Back to top

Can paranoia be treated?

Antipsychotic medication can help people who are experiencing persecutory delusions as a symptom of psychosis.

Cognitive behaviour therapy (CBT) for psychosis can also help. In CBT, mental health professionals help people try to understand the cause of their paranoid thinking and encourage them to try new ways of dealing with their distressing thoughts. CBT for psychosis can also help people deal with depression and anxiety that help perpetuate paranoid thinking (see Cognitive behaviour therapy for psychosis page).

Psychologists at the University of Oxford are developing and testing specialist forms of cognitive behaviour therapy that try to tackle worry and anxiety, poor sleep and lack of self-esteem, all of which can be instrumental in formulating and feeding paranoid thoughts.

This sort of therapy won't necessarily stop people having paranoid thoughts, but the aim is to help people feel safer and reduce the distress that such thoughts can cause.  

People who do not have a mental illness but who regularly experience suspicious thoughts may want to seek professional help if their thoughts become distressing and disrupt their life. Doctors may prescribe antidepressants to improve their mood, and cognitive behaviour therapy can help people reduce the distress they are feeling.



This page was last updated 20 April 2013 
Links checked 7 July 2016


Overcoming Paranoid and Suspicious Thoughts, A self-help guide using Cognitive Behavioural Techniques
by Daniel Freeman, Jason Freeman and Philippa Garety

Daniel Freeman is a researcher and clinical psychologist who previously worked at the Institute of Psychiatry (now Institute of Psychiatry, Psychology & Neuroscience) and is now based at the University of Oxford. Philippa Garety is a researcher at the Institute of Psychiatry and a clinical psychologist who works in mental health services run by South London and Maudsley NHS Foundation Trust.