Why do we get insomnia?

Around 10% of the global population suffers from insomnia. Contrary to popular belief, it is not more prevalent in bustling, noisy cities nor in workaholics. While we might think of insomnia as a modern malaise, people have always had trouble sleeping but are some of us more susceptible to it than others? If so, why? Where did the idea that we all need seven or eight hours sleep come from? Is it true? Can insomnia really affect our genes and shorten our lives? What really works to cure it? The experts tell us what they think works and why. And we hear from insomniacs around the world about their search for a good night’s sleep.