"There's no correct amount of sleep, says Prof Kevin Morgan, of Loughborough University's sleep research centre. The only rule is to sleep long enough to feel r

"There's no correct amount of sleep, says Prof Kevin Morgan, of Loughborough University's sleep research centre. The only rule is to sleep long enough to feel refreshed when you wake up." ^That answers the question quite well I believe. Yes, people CAN, but it is uncommon. And anything that is uncommon usually takes a considerable amount of practice. Ms. Thatcher most likely made it a concerted goal to train her self to be fully functional on just 4 hours of sleep over the weekdays. It is stated that she most likely slept longer on weekends, indicating that she was aware of her sleep schedule on weekdays vs. weekends. Things like sleep are studied so much that it is a subject overly-saturated with studies, and that too, conflicting ones. This, more than anything, shows that one's need for sleep can be controlled by him/her. I had a friend in college, he was a junior when I was a freshman. He slept through most of his morning classes and would always tweet that he was napping in the evening. He had amazing grades, though, and good enough interview skills to land him a job as an investment banker at Goldman Sachs, and he would be working in their most demanding team. In fact, his boss to-be even emailed him saying something like "Make sleep an option, not a requirement". Mike (my friend) took it literally. From the day he got that email in March, he chose to sleep 7 minutes less every 3 days with no naps. By the end of April, he was sleeping about 5.5 hours a night. For the next month, he got even crazier and took off minutes from his sleep on a daily basis. He succeeded and by the time he was at GS, he needed 2hrs 52minutes of sleep per night and was productive the rest. How do I know he was productive? Because after his internship, he was given a personalized offer letter...from the CEO. He had worked on more deals than not only all interns across the world, but more than 98% of current employees. Training our body is something we can do and just like anything, if you work hard at it, you'll more than likely be successful at some point.