According to tradition, Japanese schoolchildren preparing for entrance exams are encouraged to live by the exhausting credo of yontougoraku -- "sleep four hours, pass; sleep five hours, fail."

In other words, at an early stage in people's lives, Japanese society transmits the message that sleep has intrinsically less worth than wakefulness and is a commodity that can -- and should -- be traded for something more valuable.

"Sleep debt" has become a national focus, but it remains unclear whether managers see this as anything more sinister than just the cost of business.

However, a small company in Tokyo called Crazy, an upmarket wedding-planning boutique, has taken an unexpectedly bold stand and decided to reward sleep. It will pay its staff a bonus if they prove they sleep longer each night. If they are able to keep up a steady pace of extended slumber and manage to get at least six hours on all weekday nights, workers can accumulate the equivalent of 64,000 yen ($562) a year.