At the beginning of the 20th century, Kuniomi Ishimori of Japan and Henri Piéron of France independently found that a dog will fall asleep after receiving an intracerebral injection of a brain extract or cerebrospinal fluid from another dog kept without sleep for a long time, and predicted the presence of “sleep substances” that accumulated in the brain while the animal was awake. On 24–27 October 2009, the Japanese Society of Sleep Research (JSSR) celebrated the centennial anniversary of Kuniomi Ishimori's landmark paper, “Sleep-inducing substance(s) demonstrated in the brain parenchyma of sleep-deprived animals – a true cause of sleep”,1 at a joint congress of the 6th Congress of the Asian Sleep Research Society (ASRS), the 34th Annual Meeting of the JSSR, and the 16th Annual Meeting of the Japanese Society for Chronobiology (JSC) in the City of Osaka. Sleep professionals from around the world participated in the joint congress, and have kindly contributed their summaries of recent developments in sleep science to this special issue of Sleep and Biological Rhythms.
In recent years, the discipline of sleep science has evolved greatly with basic research on animal sleep, clinical sleep medicine, and sleep sociology. The humoral theory of sleep regulation proposed by Ishimori and Pieron postulates that the homeostatic sleep drive leads to the accumulation of somnogens during wakefulness, and that this homeostatic need is discharged during sleep. Prostaglandin D2, adenosine, and cytokines have been proposed as effective sleep substances. Osamu Hayaishi and myself, Tarja Porkka-Heiskanenn and Bertil Fredholm, and Parijat Sengupta, Sandip Roy, and James Krueger provide overviews ranging from historical notes to recent topics in the study of prostaglandin D2, adenosine, and cytokines, respectively.
Several interactions between sleep- and wake-active neurons have been proposed at the systems level in many models of sleep–wake regulation. In those models, sleep is promoted by cholinergic neurons in the basal forebrain and “sleep-on” neurons in the preoptic area; and wakefulness is induced by various aminergic and orexinergic neurons in the hypothalamus and brainstem. At this joint congress, Zhi-Li Huang, Osamu Hayaishi, and myself discussed the key roles of the histaminergic system in the tuberomammillary nucleus to illustrate the reciprocal interaction between sleep and arousal systems. Dysfunction of the orexin/hypocretin system results in narcolepsy. Takeshi Sakurai, Junko Hara, and Fang Han described the mechanistic and clinical effects of the orexin system. Kunio Kitahama, Pierre H. Luppi, Patrice Fort, Samüel Deuveilher, and Kazue Semba provided current insights into the molecular and anatomical aspects of sleep-regulatory areas of the brain. Dmitry Gerashchenko, Jonathan P. Wisor, and Thomas S. Kilduff explained their new findings implicating sleep-active, nitric oxide–producing neurons in the cerebral cortex in the modulation of slow-wave activity. Michael Lazarus, Clifford B. Saper, and Patrick M. Fuller highlighted the recent advanced molecular biological techniques for investigation of the neural circuitry regulating behavioral states.
After the joint congress in Osaka, we organized and held a satellite symposium, the “1st Summit on Asia–Oceania Sleep Research and Sleep Medicine,” supported by the ASRS and the Japan Society for the Promotion of Science, on the beautiful southern island of Okinawa, Japan. Fortunately, many core members of each individual society in the ASRS and Australasian Sleep Society participated in this satellite symposium. In a round-table discussion, the participants presented current issues of sleep medicine faced by each society to develop new regional strategies for coordinating activities between the member organizations. Yoan Chérasse summarized this “Okinawa Round-Table Discussion”. In the coming years, it will be of utmost importance for the ASRS to foster sleep research and clinical sleep medicine through exchange and coordinated training schemes between Asian countries. In addition, the ASRS must ensure that Asian sleep science is made more prominent by organizing international congresses or other activities to bring together the world's leading and up-and-coming sleep scientists.
All authors are thanked for their outstanding contributions that reflect the state of the art in the sleep field. Our cordial thanks go especially to the organizers of the Joint ASRS/JSSR/JSC Congress and the ASRS Summit on Sleep Research and Medicine: Masako Okawa (President, ASRS), Ken-ichi Honma (Secretary General, ASRS), Hitoshi Okamura (President, JSC), Hitoshi Nakamura (Okinawa Acting Committee) and Naomi Eguchi (Okinawa Acting Committee).