Such a limit exists within the EU already. The working-time directive[1] limits people to 48 hours work per week. High unemployment is unfortunately still about despite this. As to reducing this to a lower number, the UK already has 1 in 10 people 'underemployed'[2]. Fewer hours would of course be preferable, but housing and a disposable income does come first.

[1]http://en.wikipedia.org/wiki/Working_Time_Directive [2]http://www.bbc.co.uk/news/business-20526259