Medical specialty devoted to the diagnosis and therapy of sleep disturbances and disorders
Sleep medicine is a medical specialty or subspecialty devoted to the diagnosis and therapy of sleep disturbances and disorders. From the middle of the 20th century, research has provided increasing knowledge of, and answered many questions about, sleep–wake functioning. The rapidly evolving field has become a recognized medical subspecialty in some countries. Dental sleep medicine also qualifies for board certification in some countries. Properly organized, minimum 12-month, postgraduate training programs are still being defined in the United States. In some countries, the sleep researchers and the physicians who treat patients may be the same people.
The first sleep clinics in the United States were established in the 1970s by interested physicians and technicians; the study, diagnosis and treatment of obstructive sleep apnea were their first tasks. As late as 1999, virtually any American physician, with no specific training in sleep medicine, could open a sleep laboratory.
Disorders and disturbances of sleep are widespread and can have significant consequences for affected individuals as well as economic and other consequences for society. The US National Transportation Safety Board has, according to Charles Czeisler, member of the Institute of Medicine and Director of the Harvard University Medical School Division of Sleep Medicine at Brigham and Women's Hospital, discovered that the leading cause (31%) of fatal-to-the-driver heavy truck crashes is fatigue related (though rarely associated directly with sleep disorders, such as sleep apnea), with drugs and alcohol as the number two cause (29%). Sleep deprivation has also been a significant factor in dramatic accidents, such as the Exxon Valdez oil spill, the nuclear incidents at Chernobyl and Three Mile Island and the explosion of the space shuttle "Challenger".
Scope and classification.
Competence in sleep medicine requires an understanding of a plethora of very diverse disorders, many of which present with similar symptoms such as excessive daytime sleepiness, which, in the absence of volitional sleep deprivation, "is almost inevitably caused by an identifiable and treatable sleep disorder," such as sleep apnea, narcolepsy, idiopathic hypersomnia, Kleine-Levin syndrome, menstrual-related hypersomnia, idiopathic recurrent stupor, or circadian rhythm disturbances. Another common complaint is insomnia, a set of symptoms that can have many causes, physical and mental. Management in the varying situations differs greatly and cannot be undertaken without a correct diagnosis.
ICSD, "The International Classification of Sleep Disorders", was restructured in 1990, in relation to its predecessor, to include only one code for each diagnostic entry and to classify disorders by pathophysiologic mechanism, as far as possible, rather than by primary complaint. Training in sleep medicine is multidisciplinary, and the present structure was chosen to encourage a multidisciplinary approach to diagnosis. Sleep disorders often do not fit neatly into traditional classification; differential diagnoses cross medical systems. Minor revisions and updates to the ICSD were made in 1997 and in following years. The present classification system in fact follows the groupings suggested by Nathaniel Kleitman, the "father of sleep research", in his seminal 1939 book "Sleep and Wakefulness".
The revised ICSD, ICSD-R, placed the primary sleep disorders in the subgroups (1) dyssomnias, which include those that produce complaints of insomnia or excessive sleepiness, and (2) the parasomnias, which do not produce those primary complaints but intrude into or occur during sleep. A further subdivision of the dyssomnias preserves the integrity of circadian rhythm sleep disorders, as was mandated by about 200 doctors and researchers from all over the world who participated in the process between 1985 and 1990. The last two subgroups were (3) the medical or psychiatric sleep disorder section and (4) the proposed new disorders section. The authors found the heading "medical or psychiatric" less than ideal but better than the alternative "organic or non-organic", which seemed more likely to change in the future. Detailed reporting schemes aimed to provide data for further research. A second edition, called ICSD-2, was published in 2005, followed by a third edition (ICSD-3) in 2014 and a text revision (ICSD-3-TR) in 2023.
MeSH, "Medical Subject Headings", a service of the US National Library of Medicine and the National Institutes of Health, uses similar broad categories: (1) dyssomnias, including narcolepsy, apnea, and the circadian rhythm sleep disorders, (2) parasomnias, which include, among others, bruxism (tooth-grinding), sleepwalking and bedwetting, and (3) sleep disorders caused by medical or psychiatric conditions. The system used produces "trees," approaching each diagnosis from up to several angles such that each disorder may be known by several codes.
DSM-IV-TR, the "Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision", using the same diagnostic codes as the "International Statistical Classification of Diseases and Related Health Problems" (ICD), divides sleep disorders into three groups: (1) primary sleep disorders, both the dyssomnias and the parasomnias, presumed to result from an endogenous disturbance in sleep–wake generating or timing mechanisms, (2) those secondary to mental disorders and (3) those related to a general medical condition or substance abuse.
Recent thinking opens for a common cause for mood and sleep disorders occurring in the same patient; a 2010 review states that, in humans, "single nucleotide polymorphisms in "Clock" and other clock genes have been associated with depression" and that the "evidence that mood disorders are associated with disrupted or at least inappropriately timed circadian rhythms suggests that treatment strategies or drugs aimed at restoring 'normal' circadian rhythmicity may be clinically useful."
History.
A 16th-century physician wrote that many laborers dozed off exhausted at the start of each night; sexual intercourse with their wives typically occurring in the "watching period", after a recuperative first sleep. Anthropologists find that isolated societies without electric light sleep in a variety of patterns; seldom do they resemble our modern habit of sleeping in one single eight-hour bout. Much has been written about dream interpretation, from biblical times to Freud, but sleep itself was historically seen as a passive state of not-awake.
The concept of sleep medicine belongs to the second half of the 20th century. Due to the rapidly increasing knowledge about sleep, including the growth of the research field chronobiology from about 1960 and the discoveries of REM sleep (1952–53) and sleep apnea (first described in the medical literature in 1965), the medical importance of sleep was recognized. The medical community began paying more attention than previously to primary sleep disorders, such as sleep apnea, as well as the role and quality of sleep in other conditions. By the 1970s in the US, and in many western nations within the two following decades, clinics and laboratories devoted to the study of sleep and the treatment of its disorders had been founded. Most sleep doctors were primarily concerned with apnea; some were experts in narcolepsy. There was as yet nothing to restrict the use of the title "sleep doctor", and a need for standards arose.
Basic medical training has paid little attention to sleep problems; according to Benca in her review "Diagnosis and Treatment of Chronic Insomnia" (2005), most doctors are "not well trained with respect to sleep and sleep disorders," and a survey in 1990–91 of 37 American medical schools showed that sleep and sleep disorders were "covered" in less than two hours of total teaching time, on average. Benca's review cites a 2002 survey by Papp et al. of more than 500 primary care physicians who self-reported their knowledge of sleep disorders as follows: Excellent – 0%; Good – 10%, Fair – 60%; and Poor – 30%. The review of more than 50 studies indicates that both doctors and patients appear reluctant to discuss sleep complaints, in part because of perceptions that treatments for insomnia are ineffective or associated with risks, and:
Also, an editorial in the American College of Chest Physicians' (pulmonologists') journal "CHEST" in 1999 was quite concerned about the "Conundrums in Sleep Medicine". The author, then chair of her organization's Sleep Section, asked "What is required to set up a sleep laboratory? Money and a building! Anyone can open a sleep laboratory, and it seems that just about everyone is." On the accreditation process for sleep laboratories, she continues: "This accreditation, however, is currently not required by most states, or more importantly, by most insurance carriers for reimbursements... There is also an American Board of Sleep Medicine (ABSM) that certifies individuals as sleep specialists. This certification presumably makes those individuals more qualified to run a sleep laboratory; however, the certification is not required to run a laboratory or to read sleep studies." Her concern at the turn of the century was:
In the UK, knowledge of sleep medicine and possibilities for diagnosis and treatment seem to lag. Guardian.co.uk quotes the director of the Imperial College Healthcare Sleep Centre: "One problem is that there has been relatively little training in sleep medicine in this country – certainly there is no structured training for sleep physicians." The Imperial College Healthcare site shows attention to obstructive sleep apnea syndrome (OSA) and very few other disorders, specifically not including insomnia.
Training and certification.
Worldwide.
The World Federation of Sleep Research &amp; Sleep Medicine Societies (WFSRSMS) was founded in 1987. As its name implies, members are concerned with basic and clinical research as well as medicine. Member societies in the Americas are the American Academy of Sleep Medicine (AASM), publisher of the "Journal of Clinical Sleep Medicine"; the Sleep Research Society (SRS), publisher of "SLEEP"; the Canadian Sleep Society (CSS) and the Federation of Latin American Sleep Societies (FLASS). WFSRSMS promotes both sleep research and physician training and education.
Africa.
The Colleges of Medicine of South Africa (CMSA) provide the well-defined specialty Diploma in Sleep Medicine of the College of Neurologists of South Africa: DSM(SA), which was first promulgated by the Health Professions Council in 2007. The newly formed South African Society of Sleep Medicine (SASSM) was launched at its inaugural congress in February 2010. The society's membership is diverse; it includes general practitioners, ENT surgeons, pulmonologists, cardiologists, endocrinologists and psychiatrists.
Asia.
WFSRSMS members in Asia include the Australasian Sleep Association (ASA) of New Zealand and Australia and the Asian Sleep Research Society (ASRS), an umbrella organization for the societies of several Asian nations.
Europe.
The European Sleep Research Society (ESRS) is a member of the WFSRSMS. The Assembly of National Sleep Societies (ANSS), which includes both medical and scientific organizations from 26 countries as of 2007, is a formal body of the ESRS. The ESRS has published "European Accreditation Guidelines for SMCs" (Sleep Medicine Centres), the first of several proposed guidelines to coordinate and promote sleep science and medicine in Europe.
United States.
The American Academy of Sleep Medicine (AASM), founded in 1978, administered the certification process and sleep medicine examination for doctors until 1990. Its independent daughter entity the American Board of Sleep Medicine (ABSM) was incorporated in 1991 and took over the aforementioned responsibilities. As of 2007, the ABSM ceased administering its examination, as it conceded that an examination process recognized by the American Board of Medical Specialties (ABMS) was advantageous to the field. Candidates who passed the ABSM exam in 1978–2006 retain lifetime certification as Diplomates of that organization.
The American Board of Psychiatry and Neurology (ABPN), and the corresponding boards of Internal Medicine, of Pediatrics, and of Otolaryngology (ear, nose and throat, ENT) now administer collectively the Sleep Medicine Certification exam for their members. Each board supervises the required 12 months of formal training for its candidates, while the exam is administered to all of them at the same time in the same place. For the first five years, 2007–2011, during "grandfathering", there was a "practice pathway" for ABSM certified specialists while additional, coordinated requirements were to be added after 2011. The ABPN provides information about the pathways, requirements and the exam on its website. Additionally, there are currently four boards of the American Osteopathic Association Bureau of Osteopathic Specialists that administer Sleep Medicine Certification exams. The American Osteopathic boards of Family Medicine, Internal Medicine, Neurology &amp; Psychiatry, and Ophthalmology &amp; Otolaryngology grant certificates of added qualification to qualified candidate physicians.
Sleep medicine is now a recognized subspecialty within anesthesiology, internal medicine, family medicine, pediatrics, otolaryngology, psychiatry and neurology in the US. Certification in Sleep Medicine by the several "Member Boards" of the ABMS shows that the specialist:
Pulmonologists, already subspecialists within internal medicine, may be accepted to sit for the board and be certified in Sleep Medicine after just a six-month fellowship, building on their knowledge of sleep-related breathing problems, rather than the usual twelve-month fellowship required of other specialists.
Sleep dentistry (bruxism, snoring and sleep apnea), while not