Human sleep: should 8 hours be the norm or two 4 hour sessions interspersed by a few hours of wakefulness - research suggests

An interesting article, showing the powerful effect urbanisation and victory of artificial light over darkness may have profoundly changed human behaviour patterns.

http://www.bbc.co.uk/programmes/p00ngb4r

Perhaps someone might like to experiment with closing pubs and restaurants at sunset and opening them again four hours.