Update on sleep disorders in advanced Parkinson's disease: a narrative review.

Multiple types of sleep disorders are encountered in patients with Parkinson's disease (PD) and are often underreported and underdiagnosed. They include circadian disorders, insomnia, excessive daytime sleepiness, rapid-eye-movement-sleep behavioral disorder, restless legs syndrome, and obstructive sleep apnea. The prevalence of sleep problems increases early in the disease course, and sleep quality deteriorates overall as patients age and the disease progresses. At advanced stages of PD, there is a reciprocal link between sleep problems and PD manifestations: sleep problems tend to exacerbate motor and non-motor symptoms, while worsening of motor and non-motor conditions have a detrimental effect on sleep quality. As the disease advances, sleep disorders have a growing negative influence on the quality of life of both patients and family caregivers. The causes of sleep disorders in this setting are neurodegeneration of key brain structures involved in sleep, motor and non-motor manifestations interfering with sleep, and drugs interfering with sleep. Treatment can include optimisation of antiparkinsonian treatment, reduction or removal of drugs interfering with sleep, treatment of non-motor manifestations interfering with sleep, pharmacological treatment of specific sleep disorders, and non-pharmacological approaches. Efforts should be made to raise awareness among patients, families, students, physicians, charities, funders, and policy makers regarding the prevalence and consequences of sleep disorders in advanced PD.