There is a very famous study done by a man named thomas ware at the national institutes of health in th 19 nineties. Thomas ware was the guy who discovered seasonal effective disorder, basically riht. He came up wit this question: Did human beings always sleep the way they do now? So he decided to take people off the street as ordinary people, and take them off of all forms of artificial illumination for one month to see what would happen. For like the firs three weeks, what happened was that they slept a little longer than usual, repaying what were called the national sleep debt rit. At week three, every single subject in the study began waking up after