A History Of Sleep Medicine

The discipline of sleep medicine has grown dramatically over the past 30 years with diagnostic sleep laboratories now established in most countries. An understanding of sleep physiology and sleep disorders developed through the twentieth century. This review highlights some of the key developments and milestones in the establishment of this relatively new field of sleep medicine. EARLY CONCEPTS REGARDING SLEEP There has been an interest in the nature of sleep and dreams throughout recorded history. Insomnia was reported in ancient Egyptian texts and opium was used as possibly the first hypnotic medication. Our knowledge of ancient Egyptian medicine comes from the Edwin Smith papyrus, the Ebers papyrus and Kahun papyrus [1]. These medical papyri make reference to many Egyptian treatments including poppy seeds (opium) to relieve insomnia as well as an anaesthetic. Hippocrates in his texts refers to disordered sleep and dreams. Although the Hippocratic corpus is multiauthored, there are numerous references to sleep in its volumes. The text, De Victo IV, also known as, On Dreams, elaborates on sleep and dreams as a diagnostic tool for somatic complaints [2]. Dreams also played an important role in the writings of Galen. His treatise, On Diagnosis from Dreams (De Dignotione ex Insomnis Libellis) describes dreams, which may mirror the conditions of the body [3]. Dreams and interpretation of dreams are also prominent in sacred texts including the Old and New Testaments of the Bible. Despite these early references, the scientific interest in sleep has emerged over the past 100 years and the field of sleep medicine itself has only existed since the 1970's. The monograph, The Philosophy of Sleep was written by the Scottish physician, Robert MacNish in 1830 with the first American edition in 1834 [4]. MacNish regarded sleep as a passive process during which the brain had a recuperative function associated with reduced sensory input. Wakefulness on the other hand, represented the activated state of the brain. This dichotomy in which sleep was seen as a passive process and wakefulness as an active state was the prevailing view until scientific discoveries of the mid twentieth century. MacNish's text approached sleep from a philosophical rather than experimental position. The first text to analysis sleep from a physiological perspective was Henri Pieron's text entitled, Le Probleme Physiologique Du Sommeil [5]. Peiron was a French scientist who published his text in 1913 and the volume is regarded as the beginning of the modern approach to sleep research. A variety of theories were advanced in the late nineteenth and early twentieth century with regard to the nature of sleep. A vascular theory was popular and proposed that during sleep the blood flow to the brain was reduced and accumulated in the digestive tract. Around the end of the nineteenth century, a chemical process gained popularity with the theory that toxins developed during wakefulness and were gradually eliminated during sleep. The French physiologists Legendre and Pieron did experiments on sleep deprived dogs [6]. When they injected serum from these dogs into awake dogs they became fatigued. They coined the term ‘hynotoxin' to explain this endogenous sleep factor, which