Kilde på det? Var dette noe han gjorde hele livet eller bare i perioder?

Some sources claim that the legendary artist Leonardo Da Vinci was able to stay awake and alert almost 22 hours of every day, all the while working on brilliant artworks and inventions. He slept only 1.5 - 2 hours a day taking a nap 15 - 20 minutes for every four hours that he was awake.