Increased curiosity was reflected in a greater interest in people, in one's self, in ideas in general and in the world around, he said. It included "exploring my environment, rather than charging through it". Dr Robinson cited the case of TV comedy producer John Lloyd, whose work includes Blackadder and Not The Nine O'Clock News.
In his early 40s, Lloyd began weeping under his desk during recordings, unable to see the purpose of life, Dr Robinson said. Rather than get "pumped full of antidepressants", he read voraciously and treated what was wrong with him as an "engineering problem".
As a result he had the idea for the hit quiz show QI. Lloyd was a good example of how curiosity is our way of trying to deal with a world that doesn't make sense any longer, Dr Robinson said.
The middle aged are not alone in undergoing crisis, however - 22 per cent of the group aged 20 to 39 said they were in crisis and a further 36 per cent were "maybes". Only 14 per cent of over-60s reported being in a crisis.
Dr Robinson said people undergoing mid-life crisis were more likely to start reading biographies and self-help books. In those over 60, an interest in eating and cookery books was one mark of crisis.