So I stopped drinking coffee about a week ago as an experiment to measure my sleeping time without it. Nothing changed much. It's weird how I tend to stay up later when I'm alone at home versus when I'm out. I caught myself yawning around 11pm the other night, but I can still go home and be up until 3am afterward. So we yawn because we're tired or bored but not that the body is sleepy. It could also be because you're low in oxygen or that you have too much carbon dioxide. Did you know that the fetus can also yawn inside the womb?
"Beautiful Science: Ideas that Changed the World"
The Huntington Library
