&lt;i&gt;Background/Aims:&lt;/i&gt; Sleep disturbances are common in the elderly and in persons with cognitive decline. The aim of this study was to describe frequency and characteristics of insomnia, excessive daytime sleepiness, sleep-disordered breathing, REM behavior disorder and restless legs syndrome in a large cohort of persons with mild cognitive impairment or dementia. &lt;i&gt;Methods:&lt;/i&gt; 431 consecutive patients were enrolled in 10 Italian neurological centers: 204 had Alzheimer’s disease, 138 mild cognitive impairment, 43 vascular dementia, 25 frontotemporal dementia and 21 Lewy body dementia or Parkinson’s disease dementia. Sleep disorders were investigated with a battery of standardized questions and questionnaires. &lt;i&gt;Results:&lt;/i&gt; Over 60% of persons had one or more sleep disturbances almost invariably associated one to another without any evident and specific pattern of co-occurrence. Persons with Alzheimer’s disease and those with mild cognitive impairment had the same frequency of any sleep disorder. Sleep-disordered breathing was more frequent in vascular dementia. REM behavior disorder was more represented in Lewy body or Parkinson’s disease dementia. &lt;i&gt;Conclusion:&lt;/i&gt; A careful clinical evaluation of sleep disorders should be performed routinely in the clinical setting of persons with cognitive decline. Instrumental supports should be used only in selected patients.

Prevalence of Sleep Disturbances in Mild Cognitive Impairment and Dementing Disorders: A Multicenter Italian Clinical Cross-Sectional Study on 431 Patients