Figure 1 depicts a very archetypal patient with mild OSA, who sleeps 50 % of the total sleeping time on his/her back. In this sleeping position, the AHI is 30, while the average AHI in non-supine position is less than 10. This 50 % of the total sleeping in supine position is not unusual. In one of the studies reported in this book, the average percentage slept in supine position before treatment was exactly 50 %. Positional therapy is nothing more than elimination of the supine position.

Published and ongoing studies show that the new-generation positional therapy is effective and patient friendly, has no side effects, does not change sleep quality or may even improve it and is reversible, with good compliance, and this all with acceptable costs. Positional therapy can be a stand-alone therapy or can be combined with other treatments such as oral device therapy or surgery. It can be used for patients with habitual snoring as well as in patients with OSA. Its role in several other specific patient populations is currently investigated, such as will be shown in this book. Devices such as the sleep position trainer have the potential to become “game changers”.

We have tried to put a book together that can be read as a whole, but that can also be consumed per separate chapter. Such a product implicates that there is some overlap and therefore some basic principles and introductions come back from time to time. Some authors comment on the same problem from a different angle. This is inevitable, and not necessarily negative, while not all is proved yet. The upside is that if one wants to read one specific chapter only, it is not necessary to read all the preceding chapters first.