DENVER – Recent changes in the International Classification of Sleep Disorders definition of insomnia reflect a significant evolution in expert opinion regarding the fundamental nature of these disorders, according to speakers at a satellite symposium held in conjunction with the annual meeting of the Associated Professional Sleep Societies.
“One of the major differences that you'll find in the ICSD-2 versus -1 is that we now have insomnia defined as a disorder, and that all of the specific categories of insomnia subtypes have to meet the same basic general definition for insomnia disorder,” explained Daniel J. Buysse, M.D., professor of psychiatry at the University of Pittsburgh.
“The important thing, as we're educating our colleagues in the medical field, is that for many, many years we have been taught–and we've taught others–that insomnia is a symptom, not a disorder. I think that this is really undergoing an evolution. We're starting to think of insomnia as a disorder that's commonly comorbid with other medical and psychiatric conditions and may often warrant treatment in and of itself, not as part of the treatment for the other disorders,” he added.
The ICSD-2 categorization of insomnia released last year by the American Academy of Sleep Medicine was formed on a template provided by an earlier academy working group that published the first formal research diagnostic criteria for insomnia (Sleep 2004;27:1567–96).
The core ICSD-2 criteria for diagnosis of any insomnia disorder are that the patient must experience one or more sleep-related complaints that occur despite adequate opportunity and circumstances for sleep and result in some form of daytime functional impairment. Some of these manifestations of sleep-related daytime impairment are obvious, such as sleepiness, irritability, and difficulty in concentrating. Others are not necessarily so, including GI symptoms, tension headaches, and error-proneness at work.
Jodi A. Mindell, Ph.D., noted that physicians who work with children will find they're encountering some new terminology as a result of the ICSD-2 changes. For example, two of the most common childhood sleep disorders listed in ICSD-1–sleep-onset association disorder and limit-setting sleep disorder–have been combined in ICSD-2 into a single rubric: behavioral insomnia of childhood. Within this new category are three subtypes: sleep-onset association type, limit-setting type, and the combined type that involves both.
The sleep-onset association subtype typically involves children aged 6 months to 3 years who experience repeated nighttime awakenings that require parental intervention because of an inability to self-soothe. The limit-setting subtype, involving bedtime struggles and prolonged sleep-onset latency, is a common problem in 2− to 6-year-olds. These disorders respond extremely well to behavioral measures, including introduction of a sleep schedule, a short and sweet bedtime routine, and parental consistency, said Dr. Mindell, professor of psychology at St. Joseph's University, Philadelphia.
As ICSD-2 makes clear, it's important to check for physiologically based sleep problems in every child with a sleep problem. Among the most common are restless legs syndrome and periodic limb movement disorder, which has a strong family history component. In addition, obstructive sleep apnea has a 1%–3% prevalence in childhood, with a peak during ages 2–7 years; the most common cause is large tonsils, she said at the symposium sponsored by Sepracor Inc.
Parasomnias, including sleepwalking, sleep terrors, and confusional awakening, are common in young children. “For some reason, people think they don't start until the preschool years, but we see them often even in 1-year-olds,” Dr. Mindell said.
Dr. Buysse noted that paradoxical insomnia is a new term introduced in ICSD-2. It replaces sleep-state misperception, the former term for a patient's subjective feelings that a sleep problem is present in the absence of objective findings.
“It's basically a mismatch between what you might record with polysomnography and what the patient says,” he said.