[toomuchtodo]

> Has there been any scientific evidence suggesting this is the case?

Yes. http://www.telegraph.co.uk/news/science/science-news/1185131...

Before the age of 55, the circadian rhythms of adults are completely out of sync with normal 9-to-5 working hours, which poses a "serious threat" to performance, mood and mental health.

Dr Paul Kelley, of Oxford University, said there was a need for a huge societal change to move work and school starting times to fit with the natural body clock of humans.

Experiments studying circadian rhythms have shown that the average 10-year-old will not start focussing properly for academic work before 8.30am. Similarly, a 16-year-old should start at 10am for best results and university students should start at 11am.