It reduces productivity, prevents learning, reduces effective IQ, disrupts relationships, undermines creative thinking, and saps self-control. It increases the risk of depression, heart disease, diabetes, obesity, high blood pressure, and ADHD.

What is it? Lack of sleep.

Sleep is essential for learning. We spend around a third of our lives in this state, and yet we take up much less than one third of our time thinking about how to make it better. In Night School, not only can we learn all about how sleep works, but also we can find out how to get better at sleeping.

The "sleep problem" around the world is quite serious. Over 30% of British and American adults and around 80% of American teenagers do not get the sleep they need. 1 in 10 British adults takes some form of medication to help them sleep. Lack of sleep is responsible for $150 billion of lost productivity per year, and about 100,000 road deaths per year, not to mention the increased rates of heart disease and other ailments mentioned above.

But this book is not only for those who have problems sleeping. Just as it is possible to improve your fitness at any level, so it is possible to improve your sleep even if it is already good. You can become a "super-sleeper" - someone who always has a good night's sleep and wakes up refreshed. Super-sleepers have been shown to have better health, greater happiness, and more wealth, on average, than the rest of the population.

Enjoy the episode.