The Science of Sleep in Medieval Arabic Medicine

Modern sleep specialists are taught that, before the twentieth century, sleep was universally classified as a passive phenomenon with minimal to no brain activity. However, these assertions are made on the basis of particular readings and reconstructions of the history of sleep, using Western European medical works and ignoring works composed in other parts of the world. In this first of two articles on Arabic medical discussions on sleep, I shall show that sleep was not understood to be a purely passive phenomenon, at least from the time of Ibn Sina (lat. Avicenna, d. 1037) onward. Building on the earlier Greek medical tradition, Ibn Sina provided a new pneumatic understanding of sleep that allowed him to explain previously recorded phenomena associated with sleep, while providing a way to capture how certain parts of the brain (and body) can even increase their activities during sleep.