A paranoid thought is a type of anxious thought. Anxiety can cause paranoia, affecting what you're paranoid about and how long the feeling lasts. But paranoid thoughts can also make you anxious.

A paranoid thought is a type of anxious thought. Anxiety can cause paranoia, affecting what you’re paranoid about and how long the feeling lasts. But paranoid thoughts can also make you anxious.

A single restless night probably won’t cause paranoid thoughts. But if you often go without sleep, it can start to take a toll. You might not think as clearly, and you’re more likely to clash with others or have misunderstandings with them. It may start to look like people are working against you when they’re just acting like they always do. If you go without sleep for long enough, you could even start to see and hear things that aren’t there (your doctor will call them hallucinations).

Adults should shoot for 7 to 9 hours of sleep a night to stay alert and mentally healthy.

One condition, paranoid personality disorder, can make it hard to trust others. It can cause negative thoughts about people that just aren’t true, like “They don’t like me,” “They’re making fun of me,” or even “They’re plotting against me.” In some cases, no amount of evidence will convince you otherwise. This can lead to true clinical paranoia. Though you might not believe every unrealistic thought that enters your head, you believe some of them.

Schizophrenia, another serious disorder, can make it hard to tell what’s real and what’s imagined. Most of the time, you simply don’t know when your thoughts have become paranoid. Friends, loved ones, or medical professionals often have to point it out and try to help you get treatment.

Borderline personality disorder, in which you have fast emotional swings where you can worship someone one moment and hate them the next, can also cause paranoid thoughts and even clinical paranoia in some people.

Just because you feel paranoid or worry about what others think about you from time to time doesn’t mean you have a psychiatric disorder. The fact that you know your thoughts don’t make sense could be a sign of good mental health. But if these paranoid feelings happen all the time or start to get in the way of your home or work life, you might want to talk to your doctor or a mental health care provider.

Drugs like marijuana, hallucinogens (LSD, psychotropic mushrooms), and stimulants (cocaine, methamphetamine) have chemicals that make some people paranoid for short periods. Once the chemicals leave your system, the paranoia goes away, too. Days or weeks of intense alcohol abuse also can cause short-term paranoia, and over the long term, it can lead to ongoing paranoia and even hallucinations.