Limited activities and distractions along with a more physically active lifestyle allowed more time for sleep in 1905 compared to 2005.

10 hours a night, healing their bodies and getting them ready for the next challenging day.

Today, of course, we sleep much less. As the chart on page 49 shows, seven to nine hours of sleep is considered adequate for adults, and many of us don’t get anywhere near that amount. The same definitely goes for teens. On average, we’re sleeping an hour and a half less a night than we did at the beginning of the 20th century, a truly shocking reduction. Yet at the same time that we’re sleeping much less, we’re asking much more of our bodies and minds.

Today people are making demands on themselves as they never have before. If you think about how humans and animals have evolved, you’ll remember that it takes centuries for new capabilities to develop. But the digital age has pushed us to become more capable more quickly, and with that intense push has come a huge increase in the demand for alertness. We need to stay awake and functioning if we’re