Reviews for Primary Care - Fall 2007 - (Page 50) Insomnia and Neurological Disorders continued is fragmented into 3 or more periods during the 24-hour day, with the longest sleep period occurring between 2 AM and 6 AM. Patients with AD have a high prevalence of this disorder in which the etiology may be related to changes in the hypothalamus and the SCN.113 Other patients with associated neurological disorders, mental retardation, and brain injury are also commonly affected.113,114 Important factors that may contribute to ISWR may include weak external entraining stimuli such as reduced exposure to environmental light and diminished daytime activity, which are especially prevalent in institutionalized patients. Patients with ISWR may present with insomnia, hypersomnia, or the need for frequent naps throughout the day. The disorder also affects the sleep quality of the caregiver. The diagnosis of ISWR is made by reviewing the patient’s sleep log or actigraphy confirming the lack of periodic circadian rhythmicity. A history of isolation or reclusion can often aid in diagnosis. Another sleep or psychiatric disorder that can cause fragmented sleep must also be excluded. The differential diagnosis of ISWR includes factors related to poor sleep hygiene or voluntary maintenance of irregular sleep schedules. Treatment for CRDs Treatments for CRDs, including the irregular sleep-wake type, are aimed at consolidating the sleep-wake cycle with the potential use of melatonin and phototherapy. Melatonin is a natural neurohormone which is produced by the pineal gland. It plays a key role in the control of circadian rhythms. Melatonin is not regulated by the US Food and Drug Administration. Preparations vary in strength, making comparisons across studies difficult.115 Although melatonin may appear to be an effective treatment for circadian rhythm disorders (eg, jet lag), little evidence exists for efficacy in the treatment of insomnia or its appropriate dosage, especially in the elderly patient population with neurodegenerative disorders. In shortterm use, melatonin is thought to be safe, but there is no information about the safety of long-term use.115 For institutionalized patients, increased daytime social interactions and light exposure have been shown to help consolidate and improve nighttime sleep.116,117 Other strategies aimed at consolidating sleep include scheduled physical activity and minimizing nighttime light and noise.118,119 Combination therapy of vitamin B12, bright light, chronotherapy, and hypnotics produced a 45% success rate in one cohort of patients suffering from AD.120 Treatment with melatonin failed to improve sleep in one large multicenter study in AD based on actigraphy-derived measurement of sleep time.121 A recent multicenter, randomized, double-blind, placebo-controlled clinical trial funded by the National Institutes of Health at 31 AD centers in the United States demonstrated no beneficial effects of melatonin 2.5 or 10.0 mg on sleep disturbance in a well-characterized, large AD population (n 157).121,122 The data relied on actigraphically derived measures of sleep and are considered the definitive test of this hormone at this time. Light therapy or phototherapy has proven efficacy in the management of CRDs in patients with dementia. However, the optimal timing and duration of phototherapy and illumination intensity have not yet been determined.123,124 A practical approach to the management of ISWR is to begin with behavioral and environmental strategies, including bright light exposure, structured social and physical activities, and avoidance of naps during the day. During the sleep period, the environment should be conducive to sleep and consist of minimal noise, a darkened room, and a comfortable room temperature. Hypnotic or sedating psychoactive medications should be used with caution in elderly patients with dementia. Timed exposure to bright light in the morning may be helpful in some patients. Evening bright light pulses may ameliorate sleep-wake cycle disturbances in some patients with AD.124 AncoliIsrael and colleagues125 reported that when light exposure was increased throughout the day and evening, it produced a beneficial effect on sleep and on circadian rhythms in patients with dementia. It would behoove nursing homes, therefore, to consider increasing ambient light in multipurpose rooms where patients often spend much of their days, to help improve sleep quality. Another observation from the same group, evaluating the effect of bright light therapy on agitated behavior in a large sample of patients with severe AD revealed that light was associated with improved caregivers’ ratings but had little effect on observational ratings of agitation.126 The authors hypothesized that although the SCN of patients with severe AD is more likely to be degenerated, and the circadian activity rhythms deteriorate as AD progresses, it is still possible that patients with more intact SCNs—that is, patients with mild to moderate AD—might benefit from light treatment even more than those with severe AD.126 Conclusion Patients with insomnia and comorbid neurological disorders suffer from poor-quality sleep. In neurological practice, when encountering an older patient with disturbed sleep and insomnia, it is crucial to first review the patient’s medical history, psychiatric history, medications, underlying 50 VOL. 1 NO. 1 2007 REVIEWS FOR PRIMARY CARE
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