"Sometimes people ask me about night owls and early birds. And in fact, this is a real biological phenomenon. 80% of us adults like to go to bed somewhere around 10 o'clock and wake up somewhere around 6:00 AM. That's 80% of adults. And in fact, that's kind of the way our society is structured, but there are 10% of the population who would like to go to bed early and wake up early. They've always been like this and it becomes more as they get older. On the other hand, there are night owls. People like to go to bed late and wake up late. Typically we make fun of early birds and we think of the early bird special at the restaurant. And in fact, there's something called advanced phase disorder. And for a certain percentage of older people, this is a change that occurs on the other hand, teenagers like to go to bed late and wake up late. But again, most of the time they outgrow that. By the time they had their adult sleep cycle in their early twenties, but some people are like this and it has an evolutionary reason. The reason may be that while the village was sleeping, there's a small group who needed to circle and survey the outside dangers. So those night owls took the first shift. And by the time they started getting sleepy, the early birds were waking up and they took the next shift. So most of the village could sleep. So there is actually a biology behind it. It's real. And while we might be able to shift our cycle a little bit an hour here, an hour there, who we are as an early bird or a night owl is biologically set. It does tend to run in families. And sometimes it's difficult to negotiate and romantic relationships work with regards to compatibility, but these things can be done and we can shift it a little bit, but it's real and it's not made up."