Ever since comedy became a career option for funny people, society has held an idea that mental illness is somehow linked to the lifestyle of a comic.
Many of the greats - Kenneth Williams, Stephen Fry, Jim Carrey, Robin Williams, Ellen Degeneres, Paul Merton, Lee Evans, Sarah Silverman - have spoken openly about their inner struggles.
Since then, the number of major comedians who have spoken out about mental health has led to a widespread belief that humour and psychological issues are linked.
The belief is so widespread that some big names in the industry have grown tired of being asked about it.
Russell Kane, who doesn't suffer from any mental health issues, said: "There is no intrinsic link.
"I think it’s a dangerous proposition to put forward that somehow you need to be mentally ill to make something wonderful. It’s just not true."
Carl Donnelly shares the same ideas: “There is that assumption that to be a comedian that you’ve gotta have something wrong with you, that’s sort of a weird thing that you regularly hear. I don't think that's true.
"I meet a lot of comics who are absolutely the most grounded, balanced people. I know famous comedians who I wouldn’t say have got any noticeable mental health problems but i do think if they’re in there, it would draw it out because you do spend so much time on your own, ruminating on whether a gig was good enough.”
Other performers, however, thought there may be some truth to the longstanding concept.
Many, including Mark Dolan, Juliette Burton, Fern Brady, John Ryan and Harriet Dyer, shared the sentiment of "we're all mad here".
"I think it would be more difficult to find one person that wasn’t mentally ill in one way or another that was a comedian," Dyer told The Huffington Post UK. "I did my dissertation about it years ago, everyone’s off their rocker in comedy.”
Comedian Doug Segal said his cyclothymia and recurrent depressive syndrome had actually helped him develop material.
"For me, creatively, particularly in the past, more than now, I’ve been kind of driven by these bursts of madness," he said. "Of being animated, thinking really fast, a bazillion ideas a moment, having difficulty staying on thread.
"Within the comedy industry it seems to me to be so endemic within performers, some sort of mental illness, be it anxiety, there’s a lot people with borderline personality disorders, an awful lot of people on the bipolar spectrum and any number of people that have depression, and I think they’ve all utilised those as engines to fire themselves.”
The common examples we hear so often of comedians suffering from anxiety, depression, bipolar disorders or substance addictions do ring out in our minds - perhaps making us think, wrongly, that there is a higher proportion of people in the industry who suffer from such illnesses.
Taylor Glenn, who touches on her experiences with postnatal depression in her shows, says the persevering notion of most comedians being mentally ill is caused by the openness within the industry, giving the public a disproportionate view.
"I think the fact is we're more open about it. I think comedy's always been a forum to address the taboo, and we still have a ways to go with taking away the stigma of mental issues.
"What I see is a higher proportion of comedians talking about mental health issues openly."
Felicity Ward, whose 2014 show 'What If There's No Toilet?' touched on the link between her anxiety and Irritable Bowel Syndrome, echoed Glenn's explanation.
"We're on stage and we're just telling our thoughts all the time, so people are very exposed to the depravity that's going on in our heads.
"I think there's just less of a private life when you're a stand-up."
With even people entrenched in the industry unable to reach a consensus on the issue, there's still one place to turn for answers: science. Psychologists have been greatly interested in the supposed link between comedy and mental health for years.
A 2014 Oxford study looked intensively at psychotic traits in comedians, and used an online survey to compare comics to actors.
The study found that respondents from the comedy industry displayed unusually diverse levels of both introversion and extroversion, and reported more psychotic traits than the control group of actors.
Joint-authory Gordon Claridge said: "The creative elements needed to produce humour are strikingly similar to those characterising the cognitive style of people with psychosis - both schizophrenia and bipolar disorder."
“I certainly wouldn't call myself a happy human being. All the comedians I've known have been deeply depressive people, manic depressive... They kept it at bay with this facade.”
The trio of scientists concluded that experiencing psychosis enabled people to process information in unusual ways and think outside the box - which could be conducive to coming up with jokes.
It was, however, not a perfect study. Self-reported online surveys can be unrepresentative, and even the researchers who conducted the study admitted "it did not enable us to assess the response rate of those surveyed, or to judge the representativeness of the samples".
Others within the psychiatric community also panned the research, with Dr James MacCabe of the Institute of Psychiatry at King's College London saying "this study tells us some interesting things about the differences between comedians and actors but not about the link with psychosis".
The results of the study should simply be taken with a pinch of salt - they did not of course prove that all comedians are mentally ill. They simply found that, of the small group of people they surveyed, those identifying as comedians shared some similar aspects of the cognitive process with people experiencing psychosis.
“It is impossible to answer a question as broad as ‘is creativity related to mental illness'.”
Senior lecturer in clinical psychology at the University of Southampton, Dr Nick Maguire, acknowledges that there may be a connection between depression and comedy but said "it's certainly not a very strong one".
On the comedy circuit, performers are unable to agree and even science is unable to provide us with an answer. What isn't in doubt is the importance of listening to comedians who fight stigma by speaking out about mental health in an accessible way.
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