Shakespeare was often right but not always.
It’s hard to escape the conclusion that Shakespeare’s slumbering Falstaff, described in Henry IV Part 1 as a ‘bed-presser’ and a ‘huge hill of flesh’ suffers from sleep apnoea, aggravated by grog. When Peto finds him ‘fast asleep behind the arras and snorting like a horse,’ Prince Hal remarks, ‘hark how hard he fetches breath.’ Shakespeare describes him with text book accuracy.
On the other hand, Julius Caesar asks to be surrounded by men ‘that are fat’ and ‘such as sleep at nights’. In this case, Shakespeare was mistaken if he thought fat people are better, as opposed to longer, sleepers. They only look that way, as anyone with sleep apnoea will tell you. But if he was saying that better sleepers make better leaders, he may well have had a point. Brutus, one of the traitors, does not sleep on the night before he joins the assassination.