Sleep problems are highly prevalent in patients with dementia. As sleep disturbances in patients with dementia may increase caregiver-burden, a standardized treatment for sleep disorders should be established. However, there are limited scientific reports regarding effective treatments for sleep disorders in dementia patients. Considering the multifactorial nature of sleep problems in dementia, non-pharmacological approaches and proper sleep hygiene are considered the initial therapies. Comorbid systemic diseases and medications that affect sleep should also be carefully managed to reduce negative effects on sleep. Most previous research has focused on a limited number of sleep disorders and on patients with Alzheimer's disease (AD) only, but clinical focus on other neurodegenerative dementias has increased as the accuracy of their clinical diagnosis has improved. The current classification of neurodegenerative dementias is based on the major constituent protein of the neuropathology, including amyloid-beta, tau, alpha-synuclein, and TAR DNA-binding protein of 43 kD (TDP-43). As the clinical presentation reflects the particular population of neurons that are targets of the disease process, the frequency, type, and severity of sleep disturbances markedly vary with factors such as duration, severity, and subtype of dementia. Some recent studies support this idea, but there are limited findings on the correlation of these factors. Dementia with Lewy bodies (DLB) is the second most common neurodegenerative disease after AD. The fourth report of the DLB consortium was published in 2017. In the revised clinical criteria, REM sleep behavior disorder (RBD) was defined as one of the core clinical features of DLB. Hypersomnia, usually presenting as excessive daytime sleepiness, was listed in the supportive clinical features. Considering the close relationship between RBD and alpha-synucleinopathy based on many clinicopathological studies, the diagnosis of DLB is expected to improve, especially in terms of its differentiation from AD. As a result, increased diagnostic specificity of AD enables more rigorous clinical trials regarding sleep disorders in patients with AD. Moreover, the differential diagnosis of dementias based on the clinical history of sleep disorders may provide an opportunity to pay closer attention to sleep disturbances in patients with dementia. This review focuses on the current status and issues regarding the management of sleep disorders in patients with dementia.
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