What is insomnia disorder?

Updated: Oct 09, 2018
  • Author: Sufen Chiu, MD, PhD; Chief Editor: Caroly Pataki, MD  more...
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Insomnia disorder, classified in DSM-5, which in DSM-IV was described as primary hypersomnia, includes normal sleep efficiency, sleep-wake cycles, and sleep architecture. Patients present with a normal variant sleep pattern except for dissatisfaction with sleep quantity or quality. This may be a lifelong pattern. The problems with sleep are often associated with the following:

  • Difficulty initiating sleep: In children, this includes difficult initiating sleep without a caregiver

  • Difficulty maintaining sleep: In children, this includes difficulty returning to sleep without caregiver

  • Early morning awakening with difficulty returning to sleep

Other criteria for insomnia disorder require significant distress or impairment, occurring 3 nights per week, present for at least 3 months, and occurring despite sufficient time for sleep. The insomnia is not better explained or occurs exclusively in conjunction with another sleep-wake disorder. The insomnia is not due to the physiological effects of a substance, and coexisting mental/medical conditions do not fully explain the insomnia. If an individual reports feeling unrested (nonrestorative sleep) despite adequate duration and no difficulty initiating or maintaining sleep, then a diagnosis of unspecified insomnia disorder is given.

Difficulty initiating sleep means that the subjective sleep latency is greater than 20-30 minutes. Difficulty maintaining sleep is the subjective time awake after sleep onset is longer than 20-30 minutes. There is no standard definition of early morning awakening, but it usually requires awakening 30 minutes before the scheduled time or before total sleep time reaches 6.5 hours. When considering the final awakening time, it is also important to consider when bedtime occurs. For example, a child who initiates sleep at 7 pm versus 9 pm and awakens at 5 am may need to go to bed later.

The pathogenesis of insomnia disorder is poorly defined. First episode often occurs in young adulthood. However, it can also begin in childhood or adolescence. It can be associated with life changes and resolve when the precipitating event subsides. For some, the insomnia can persist because of conditioned arousal from the precipitating event. In children, the conditioned factors include needing a parent to be present to initiate sleep, but they can also include absence of a consistent sleep schedule. In adolescents, insomnia is more often triggered by irregular sleep schedules. Polysomnography (PSG) is of limited value in evaluating insomnia disorder in children. [4]

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