Asclepius (Fig. 8.2), according to myth, was the son of the god Apollo and the mortal woman Coronos. He was initially revered as a hero and physician of great skill and by the end of the sixth century BC would be elevated to the status of the God of Medicine. His descendents, who carried on the medical arts that he perfected, were known as Asclepiads, a term that would come to refer to all physicians [17]. The Rod of Asclepius, represented by a staff entwined by a single snake, continues to be used as a symbol of medicine to this day¹ [18], appearing most notably in the logos of the American Academy of Sleep Medicine (http://​www.​aasmnet.​org/​) and the American Board of Sleep Medicine (http://​www.​absm.​org/​).

The cult of Asclepius would prove to be one of the most widespread and enduring in the Greco-Roman world. From its origins in Epidaurus, the cult disseminated widely from the fifth century BCE onward, with Asclepieion sanctuaries, or Ascelpieia, being established in an embassy-like fashion throughout the Greco-Roman world [17]. The total number of such sanctuaries has been estimated at up to 513 [18], and it is likely that an Ascleipieoion was a standard institution in any Greco-Roman city or large town. These sanctuaries functioned well into the sixth century AD [17].

The sanctuaries of Asclepius functioned as modern-day spas, if not the precursors to modern-day hospitals. In general, attempts were made to locate Asclepieia in scenic locations, or on sites of religious significance, and almost all of them were built on the site of springs. The Asclepieion of Epidaurus, the center of the cult, boasted an extensive collection of buildings and facilities, including temples to Asclepius, Artemis, Apollo, and Aphrodite; as well as a gymnasium, library, guesthouse, stadium, baths, and a theater. An enigmatic circular building known as the Thalos contained an underground labyrinth and snake pit (an animal considered to be sacred to Asclepius) [17, 18].

The core principle of treatment in the Asclepieion was the practice of dream incubation . Fragments from various literary sources allow us to work out what the process of dream incubation entailed. Prior to undergoing dream incubation, various animal sacrifices were made, the cock being a customary sacrificial animal for Asclepius, with further food offerings of honey cakes, cheese cakes, bakemeats, and figs placed upon a “holy table.” Preparatory rituals included prayers in the temple, washings in the sacred well, and the adornment of white robes. Supplicants were then led to the abaton where they lay on pallets placed on the floor throughout the sacred room. With the extinguishing of the light, they attempted to fall asleep with the hope of receiving a dream visitation from the god Asclepius [17, 18, 19].

Asclepius, in such dreams, would appear in forms similar to that presented in statues of his likeness, either as a beautiful young man or as an older, bearded man of experience, with a gentle and calm demeanor. He could be accompanied by a retinue of assistants, including his daughters, such as Iaso and Panacea, as well as serpents and dogs. Inscriptions in the Asclepieion of Epidaurus, which date from the fourth century BCE, detail some of the cures carried out by Asclepius:

Ambrosia of Athens, blind of one eye. She came as a supplicant to the god. As she walked about in the Temple she laughed at some of the cures as incredible and impossible, that the lame and the blind should be healed by merely seeing a dream. In her sleep she had a vision. It seemed to her that the god stood by her and said that he would cure her, but that in payment he would ask her to dedicate to the Temple a silver pig as a memorial of her ignorance. After saying this, he cut the diseased eyeball and poured in some drug. When day came, she walked out sound. ( InscriptionesGraecae, IV, 1 nos. 121–22, in [17] T. 423)

As alluded to in this passage and others, the early belief was that the dream figure of Asclepius carried out his treatments directly in a miraculous fashion, using both medicinal and surgical means (thus giving the term “sleep medicine” a much more different connotation in the ancient world than we know it today). As suggested by Aristophanes (456–386 BCE) in his play Platus [20], the process of dream incubation in the abaton may have involved a certain amount of deceptive theatrics, with temple staff dressing up in the roles of Asclepius and his minions, and appearing at the expected time. Supplicants may even have been given soporific or narcotic substances which may have impaired their judgment and even allowed surgical procedures to be conducted on them [21].

Such miraculous cures, however, are not evident in later accounts of Asclepieion dream incubation. The Greek orator Aelius Aristides (118–180 AD) in his Sacred Orations [19] documented the course of an unspecified illness he was suffering from for nearly 17 years, and which brought him into contact with several Asclepieia-seeking treatment. Many of the 130 dreams he described in the work exhibit the discontinuity and bizarreness of content that are reflective of actual dreams. When Asclepius does appear to Aristides in a dream, he acts as more of a consultant, not performing cures directly, but recommending to Aristides various treatments or courses of action. More symbolic dreams seem to have been interpreted by Aristides himself, after discussion with priests, doctors, and friends. Moreover, the medical treatments recommended to Aristides were not out of keeping with rational- or secular-based medicine of the time (Galen noted that such conservative treatments were more likely to be followed by patients when they were recommended by the god Asclepius) [17], T 401). There is evidence to suggest that physicians were at least tangentially associated with the cult of Asclepius [17, 19, 22].

The cult of Asclepius lasted over a millennium, declining only with the decline of paganism itself. Dream incubation would come to be practiced in some early Christian churches, a practice which continued into the Middle Ages . According to Hamilton (1906) [15], remnants of dream-incubation practice could be found in the early twentieth century.

While the ancient Greeks and Romans took their belief in the divine nature of dreams to new heights, it is also in this time period that this prevailing view was challenged by philosophers and natural scientists. It is in this time period that we begin to see the first rationalistic accounts of sleep and dreaming in history [23] .

Alcmaeon of Croton (early fifth century BCE) provides us with perhaps the first theory of sleep, stating that sleep results from the withdrawal of blood to the “blood-carrying veins,” while awakening results from the reverse process [24]. Empedocles (c. 490–430 BCE) described sleep as occurring from a moderate cooling of the blood, with death being the result of total cooling [25]. A similar “cooling” hypothesis was ascribed to Parmenides (early fifth century BCE) [26]. Leucippus (early fifth century BCE) described sleep as something that happened to the body, not the soul, and occurred when “the excretion of fine-textured atoms exceeds the accretion of psychic warmth” (Plutarch Epitome V.25.3) [27]. Diogenes of Apollonia (fifth century BCE) believed that sleep resulted from blood filling all the veins and forcing air into the back and belly which warms the breast [28] (Pseudo Plutarch, PlacitaPhilosophorum, 5.23).

With respect to dreaming , both Heraclitus (c. 535–475 BCE) and Empedocles alluded to the subjective nature of dreams. Heraclitus further described dreams as the kindling of an “inner light” that occurs when vision is extinguished [29, 30] (Fragment 26 and Fragment 89). However it is Democritus of Abdera (460–370 BCE) who provides us with the first systemic theory of dreams. Democritus, in keeping with the theory of “atomism” he promulgated, described dreams as the result of fast-moving films of atoms or “effluences” ( eidōla), which are emitted by all objects (including people), penetrating the body during sleep, and impacting directly on the soul [27] (pp. 132–134). This theory, which still sees dreams as a largely externally generated phenomena, would continue to have a long-standing influence [23].