Sleep is a prerequisite for a healthy life. It plays a major role in the quality of our waking hours: it affects memory, attention, intellectual performance, brain development and general physical equilibrium.

In France, six million people say they suffer from insomnia and three million from abnormal somnolence. Attention and concentration disorders, lack of motivation, nervous tension and depressive moods may all be signs of insomnia. Abnormal somnolence results in greater accident risk, diminished performance, and social and family problems.

In this book we learn what to do to sleep well, so as to keep healthy and fit.

Most of us spend a third of our lives sleeping. By improving the quality of sleep we will improve the quality of our waking lives.

In accessible language, this book explains everything we should know about sleep. What purpose does it serve? Why do we sleep during certain hours and not during others? What happens to the body when it is asleep? What role do dreams play?

The author offers advice and replies to the most frequently asked questions about sleep. What type of sleeper are you? How long is your optimal sleeping time? Are afternoon naps beneficial? What should you do if you cannot fall asleep — or if you start nodding off at the wrong moment? Can you learn what to do to fall asleep? How can you improve the quality of your waking life? Is medication necessary, or is it harmful?

All types of sleep disorders are examined here: occasional or chronic insomnia, abnormal somnolence, sleep apnoea, as well as those caused by job-related problems, fear of flying and physical or psychiatric diseases. For each type of disorder, the author gives recommendations and suggests treatment.

Michel Billiard is an honorary professor of neurology at the University of Montpellier and a former president of the European Sleep Research Society.