&gt; Has there been any scientific evidence suggesting this is the case?<p>Yes. <a href="http:&#x2F;&#x2F;www.telegraph.co.uk&#x2F;news&#x2F;science&#x2F;science-news&#x2F;11851311&#x2F;Staff-should-start-work-at-10am-to-avoid-torture-of-sleep-deprivation.html" rel="nofollow">http:&#x2F;&#x2F;www.telegraph.co.uk&#x2F;news&#x2F;science&#x2F;science-news&#x2F;1185131...</a><p>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 &quot;serious threat&quot; to performance, mood and mental health.<p>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.<p>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.