The device titled, "nap alarm", is fixed to an ear, buzzes the moment the wearer’s head nods forward. The buzzing causes a ticklish sensation, thereby casting out the alpha waves which cause sleepiness.

Few Japanese sleep more than six hours a night and it is common to see whole rows of office workers fast asleep on commuter trains.

Japanese politicians are notorious for sleeping in parliament, while "salary men" frequently doze during interminable meetings in offices where long hours are the norm.

Samizo invented the device worth 9 pound, after he dozed off while driving and crashed into a stationary car.

"It is highly effective but the sensation makes you giggle as well," the Telegraph quoted him as saying. The device was initially used by taxi and truck drivers, but it has proved an unexpected hit with the wider population. Sales of the vibrating alarm, which resembles a hearing aid, now outstrip production.

The device has even been ordered for trainee Zen monks who are required to sit for hours in meditation. Traditionally the trainees were woken with a whack from a stick wielded by a priest.