The secret of happiness could be as simple as having a quick snooze in the daytime, research suggests.
A study found that taking naps of less than 30 minutes improves our sense of well-being, as well as boosting performance, according to Daily Mail.
The researchers have suggested a new word to describe the contented feeling after a brief doze: "nappiness".
Professor Richard Wiseman, of the University of Hertfordshire, said: "Previous research has shown that naps of under 30 minutes make you more focused, productive and creative, and these new findings suggest ... that you can also become happier by just taking a short nap."
However the study found that those who took longer naps were less happy than those who did not nap at all.
More than 1,000 people took part in the study, conducted for the Edinburgh International Science Festival.
Among the participants, 66 per cent of "short nappers" who slept for less than half an hour reported feeling happy, compared with 56 per cent of 'long nappers' and 60 per cent of those who never napped.
Short nappers had an average happiness score of 3.67 on a five-point scale, no-nappers 3.52 and long-nappers 3.44.
The research also showed that 43 per cent of participants aged 18 to 30 were taking long naps during the day, compared with just 30 per cent of those over 50.
Only 11 per cent said they were allowed to take naps at work.
Prof Wiseman said: "A large body of research shows that short naps boost performance. Many highly successful companies, such as Ben & Jerry's and Google, have installed dedicated nap spaces, and employees need to wake up to the upside of napping at work."
Napping for just 20 to 30 minutes is said to improve creativity, focus and performance.
One study carried out by the American space agency Nasa on sleepy military pilots found that taking a 26-minute nap while the co-pilot was in control boosted alertness by 54 per cent.
On the other hand, frequent hour-long naps are associated with an 82 per cent increase in the risk of heart disease.
Former prime ministers Sir Winston Churchill and Margaret Thatcher both claimed to have slept just four hours a night, but took regular daytime naps.