Comedians have personality types linked with psychosis, like many other creative types, which might explain why they can entertain, researchers claim.
They score highly on characteristics that in extreme cases are associated with mental illness, a study by Oxford University researchers suggests.
Unusually, they have high levels of both introversion and extroversion.
The team says the creative elements needed for humour are similar to traits seen in people with psychosis.
The idea that creativity in art and science is connected with mental health problems has long captured the public imagination.
However, there has been little research on whether comedians have some of the traits - in a healthy form - associated with psychosis (delusions or hallucinations that can be present in schizophrenia and bipolar disorder).