The naked truth of how to be happy may have been uncovered by south London scientists.
Research into the psychological effects of nudism suggests casting off clothes as well as cares may be the key to contentment and well-being.
It was found people taking part in naturist activities felt better about themselves, their bodies and their lives overall.
The more time they spent completely or partially naked, the happier they were.
Lead researcher Dr Keon West, from Goldsmiths, University of London in New Cross, said: "The naturists have been saying this for some time.
"However, despite a lot of positive claims, little to no empirical research has investigated whether naturist activity (rather than attitude or beliefs) actually makes us happier or, just as importantly, why it makes us happier."
An online survey followed by psychological assessments of people attending two naturist events found "immediate and significant improvements in body-image, self-esteem and life satisfaction" when clothes were shed.
Analysis of the data suggested seeing other people naked was more important than being naked yourself.
Dr West pointed out that for a long time many people, including health experts, assumed public nudity was a sign of psychological dysfunction.
He thought more research was needed involving a wider range of participants. Most of those taking part in the survey were white, heterosexual and middle-aged.
Naturism may offer a low-cost and simple solution to body dissatisfaction, Dr West added.
"At the very least, this is worth investigating," he said.
The findings appear in the Journal of Happiness Studies.