Why you need more than 4 hours' sleep to rule the world
One of the things we learnt from Donald Trump's doctor this week was that he only has four to five hours sleep a night. His doctor wasn't worried though, saying that he's "just one of those people who doesn't need a lot of sleep". Do such people exist? Margaret Thatcher famously operated on little sleep. As did Barack Obama - so were there repercussions for them? (Image: Sleeping baby, credit: BBC)