Healthy sleep is required for restoring functioning and vitality, promoting memory consolidation, and maintaining immune function. However, many individuals are affected with sleep disorders. There are about 60 million Americans who have problems with sleep, with associated costs of about $16 billion each year in medical care. Insomnia affects about 10% to 15% of the population, sleep apnea affects about 10%, followed by other sleep disorders, such as restless legs syndrome and circadian rhythm disorders. Untreated sleep disorders can increase the risk of heart disease, motor vehicle accidents, memory problems, depression, and impaired functioning.1-3
The DSM-5 Sleep-Wake Disorders Work Group worked closely with other nosology systems (eg, International Classification of Sleep Disorders, third edition [ICSD-3]) to incorporate changes in diagnoses. DSM-5 sleep-wake disorders are now more in sync with other medical disorders and sleep disorders classificatory systems. In DSM-5, the pathological and etiological factors associated with sleep-wake disorders are taken into consideration, as is the increase in awareness and knowledge gained from sleep studies. The aim is to increase uniformity and consistency among health care professionals when they are assessing and treating patients with various sleep disorders. Sleep-wake disorders comprise 11 diagnostic groups:
• Insomnia disorder
• Hypersomnolence disorder
• Obstructive sleep apnea hypopnea
• Central sleep apnea
• Sleep-related hypoventilation
• Circadian rhythm sleep-wake disorders
• Non–rapid eye movement (NREM) sleep arousal disorders
• Nightmare disorder
• Rapid eye movement (REM) sleep behavior disorder
• Restless legs syndrome and substance-/medication-induced sleep disorder
Growing evidence has shown that sleep disorders coexist with other medical and psychiatric disorders and may not be mutually exacerbating. DSM-5 underscores the need for independent clinical attention of a sleep disorder regardless of mental or other medical problems that may be present. DSM-5 also recognizes that coexisting medical conditions, mental disorders, and sleep disorders are interactive and bidirectional. Two previous diagnoses have been eliminated: sleep disorder related to another mental disorder and sleep disorder related to another medical condition.
The most significant change in sleep-wake diagnostic criteria is in the insomnia classification (Table). The DSM-IV distinction into primary and secondary insomnia is removed in DSM-5. This stresses the comorbid nature of insomnia and calls for treatment of both insomnia and the medical disorder. This change in insomnia diagnostic criteria in ICSD-3 and DSM-5 implies a paradigm shift.
Insomnia is insomnia is insomnia, according to Michael Sateia,4editor of ICSD-3. Insomnia is a disorder in itself that needs independent clinical attention. The diagnostic criteria have been made more specific by putting in frequency criteria; in addition, the duration has been changed to 3 months. DSM-5 and ICSD-3 insomnia diagnostic criteria are similar because of collaborative efforts between the American Psychiatric Association and the American Association of Sleep Medicine classification task forces. The changes in insomnia diagnostic criteria give it more specificity and ensure greater uniformity. According to Charles Reynolds III, MD, chair of the DSM-5 Sleep-Wake Disorders Work Group, “To achieve optimal treatment outcomes in people with both a psychiatric disorder and insomnia, the clinician needs to target both disorders.”5
Mr S, a 53-year-old man, is referred to a sleep disorders clinic for evaluation of insomnia and daytime somnolence. He has been struggling with depression and anxiety, for which he is being treated.
Mr S reports that he has had insomnia for many years and that it had gotten worse in the past 10 years. He has trouble with sleep initiation—it often takes him more than an hour to get to sleep. Once he is asleep, he wakes up multiple times then struggles to get back to sleep. He tosses and turns in bed until morning and gets up feeling tired and exhausted.
His primary care physician prescribed zolpidem, but this caused sleepwalking episodes, so Mr S discontinued it. Mirtazapine was tried, but it caused weight gain and was also discontinued. He takes trazodone for insomnia and fluoxetine for depression. This combination has been helpful, but he still has persistent symptoms of insomnia and depression. His wife reports that he snores and there have been occasions when he stopped breathing while sleeping. He has comorbid type 2 diabetes mellitus, hypertension, and gastroesophageal reflux disease.
The primary diagnosis is DSM-5 insomnia disorder. Given the comorbid symptoms of depression and obstructive sleep apnea, it would be difficult to evaluate whether Mr S has DSM-IV primary insomnia; DSM-5 allows the clinician to make a causal attribution between insomnia and comorbid depression and obstructive sleep disorder.
Comorbid obstructive sleep apnea is diagnosed on the basis of clinical and polysomnographic evaluations. Mr S is treated with continuous positive airway pressure. He reports improvement in his energy level during daytime, but he continues to struggle with insomnia. His nighttime awakenings decreased to 2 or 3 times and nocturia is diminished as well. Despite these improvements, he still struggles with insomnia. An increase in the dose of trazodone by 75 mg and initiation of cognitive-behavioral therapy for insomnia (CBT-I) helped him significantly. Mr S is sleeping bet- ter and continues CBT-I; treatment with trazodone continues, with a slow and gradual taper.
Dr Khurshid is Clinical Associate Professor and Chief of the Neuromodulation and Sleep Disorders Program in the department of psychiatry at the University of Florida College of Medicine in Gainesville. He reports no conflicts of interest concerning the subject matter of this article.
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