Sleep medicine, though no specific date, person or event can be identified as its beginning, can be traced back to ancient Egyptian times (about 1300 B.C.) when opium was widely used as therapy for insomnia. However, sleep technology cannot be said to truly exist until the development of electroencephalogram, or EEG, which was first applied to human in 1924 by German physiologist and psychiatrist Johannes Berger (Fields, 2009). He demonstrated the difference in brain activity between wakefulness and sleep utilizing EEG, and made EEG a clinical and diagnostic tool for brain dysfunction. The currently and widely accepted five different stages of sleep, stage 1 to 4 and REM, were established by Alfred Loomis, E. Newton Harvey and Garret Hobart in 1937, also by utilizing EEG (Loomis, Harvey, & Hobart, 1937).
Contemporary to EEG was the concept of circadian rhythm. Starting in the early 1900s, in which Karl von Frisch and IngeborgBelingwere inspired by observing bees visiting flowers with a degree of regularity, chronobiology was widely studied and its existence in all organisms were generally accepted by the 1960s. The decisive experiment of human circadian rhythm was carried out by Jules Aschoffand Kurt Weverin March 1962 (Culebras, 2007). Done by isolating human subjects in an underground WWII banker without any environmental cues, Aschoffand Weverestablished that a cycle of human circadian rhythm was slightly longer than 24 hours. The importance of light-dark cycle on the guidance of human circadian rhythm was later demonstrated by Czeislerand colleagues (Czeisleret al., 1999).
In addition to the study of chronobiology and changes of electric potentials generated by cortex during sleep, other parameters influencing sleep were noted and investigated. One such parameter is the movement of the eyes during sleep, something that was firstly reported by William Griesingerin 1868 (Mancia, 2006). This finding along with another sleep parameters, such as muscle twitching, led to the discovery of “rapid eye movement (REM) sleep” by Nathaniel Kleitmanand his student Eugene Aserinskyin 1953 when documenting dreaming sleep ("Kleitman, father of sleep research," 1999). The combination of the physiologic signals from the brain (EEG), eye movement (EOG) and muscle activity (EMG) gave rise to the idea of modern polysomnography(PSG), a multi-parametric test widely used in the study of sleep medicine and in the diagnosis of sleep disorders. Indicators of breathing functions were further added after the indication of obstructive sleep apnea in the 1965 (Gastaut, Tassinari, & Duron, 1965).
In 1986, Allan Rechtschaffenand Anthony Kales developed a standardized method for sleep stage scoring in their text entitled “A Manual of Standardized Terminology, Techniques, and Scoring System for Sleep Subjects of Human Subjects” (Rechtschaffen& Kales, 1968). Many sleep stage scorings carried out in sleep study today are still mainly based on the Rechtschaffenand Kales criteria.
In 1977, multiple sleep latency tests, MLST, were created by Mary Carskadonand William C. Dement. They were developed by repeating a project called the “90-minute day” conducted by Dr. Dement in 1970. Sleep latency was measured in MLST and it was based on the idea that the sleepier the patient, the faster they fall asleep (Carskadon& Dement, 1977; Carskadonet al., 1986).
Besides the diagnostic value described above, traditional sleep technology also has a role in the treatment of sleep disorders. Among them are continuous airway pressure (CPAP) applied to obstructive sleep apnea in 1981 (Sullivan, Berthonjones, Issa, & Eves, 1981); radiofrequency technique for sleep disordered breathing starting from 1997 (Coureyet al., 1999; Loube, 1998; Powell, Riley, & Guilleminault, 1999; Powell, Riley, Troell, Blumen, & Guilleminault, 1997; Powell et al., 1998). Even with the advancements in technology, treatment using primarily traditional sleep technology is still widely utilized in a variety of clinical settings.
The Scope of Modern Sleep Technology
By definition, the sleep technology is the application of technology on sleep medicine. Our definition, “Sleep Technology” is the field of new and improved ways to monitor and assess sleep and circadian rhythms, in addition to any intervention that may be used to promote sleep, to prevent, diagnose or treat sleep disorders or for rehabilitation or the long-term care of sleep condition in some specific groups. This includes the use of pharmaceuticals, devices, procedures and organizational systems. Based on this definition, sleep technology is for:
1. the evaluation and management of sleep disorders
2. the prevention of sleep disorders and reduction of morbidity of sleep disorders
3. improving the quality of sleep, sleep environment, daytime performance and quality of life
According to our definition of sleep technology, the categories of development so far are listed as follows:
o Clinical services: methodology and instrumentation of screening, diagnosis and management of sleep disorders
o Basic/clinical sleep research
o Sleep environment
o Sleep modeling
o Sleep-related transportation & work place safety and solutions
o Sleep technology innovation
o Educational courses and training program on sleep science and technology
Excerpt from: Chiang, Rayleigh Ping-Ying, M.D., M.M.S.(2012). Introduction to Modern Sleep Technology". Springer, Dordrecht, The Netherlands, 1st ed. ISBN 9789400754690.