5 hours isn't necessarily short. I read somewhere that in general people work best on between 5 and 7 hours although obviously everyone is different. If you only get 4 hours and you might want to dismantle the welfare state

. Apparantly it used to be more common to get 8-9 hours and was detrimental to overall health. Clearly diet etc also played a part but then we also used to be healthier as a nation due to the amount of everyday exercise we got, like walking to the shops rather than drive that mile to get the paper.