Members of the Laughter Yoga club practise laughing to see whether it really is the best medicine during morning exercise at a public park in Hanoi.
For the past two years, several hundred people have been gathering each morning at a public park in central Hanoi to practise laughing under the instruction of yoga master Le Anh Son in the belief that this will help them to be happier, fight disease and relief the stresses of daily life.
Members of the Laughter Yoga group chuckle and chortle for 45 minutes. They wave their arms, clap and march around, making funny faces at each other in an effort to get each other to laugh even harder
Laughter yoga was launched in 1995 by Dr Madan Kataria, a physician, in India and there are now more than 6,000 clubs in 60 countries.
The combination of unconditional laughter and yogic breathing is said to stretch muscles and trigger endorphins – the chemical in the brain known for its feel-good effect.