Sleep disturbances and disorders in the memory clinic: self-report, actigraphy, and polysomnography

Background: Sleep disturbances are common in dementia but rarely studied in memory clinics. Objective In a memory clinic setting we aimed to (1) identify rates of obstructive sleep apnea (OSA), abnormal sleep duration, circadian phase shift, insomnia, poor sleep quality, and REM sleep behavior disorder (RBD); (2) assess concordance between self-reported and actigraphy-derived measures; investigate associations between sleep disturbances; and (3) neuropsychological performance and (4) cognitive status. Methods: Adults over 50 at a memory clinic between 2009-2024 were included. OSA was assessed via polysomnography and prior history. Sleep duration and circadian phase were measured by self-report and actigraphy. Self-report questionnaires evaluated insomnia, sleep quality, and RBD. Global cognition, processing speed, memory, and executive function were assessed. Analysis of Covariance and multinomial logistic regression examined the impact of OSA, sleep duration, insomnia, and sleep quality on cognition and cognitive status. Results: 1234 participants (Mage 67.2, 46%M) were included. 75.3% had OSA, while 12.7% were previously diagnosed. Insomnia affected 12.0%, 54.3% had poor sleep quality, and 14.2% endorsed RBD symptoms. Self-reported short (30.5%) and long (10.2%) sleep exceeded actigraphy rates (8.5% and 5.1%) with poor concordance between measures. OSA was linked to impaired global cognition and memory (p < 0.05). Prolonged sleep predicted deficits in global cognition, processing speed, memory, and executive function and a higher risk of aMCI (all p < 0.05). Poor sleep quality was linked to better memory (p < 0.05). Conclusions: Despite discrepancies between self-reported and objective prevalence rates, sleep disturbances are highly prevalent in memory clinics and impact cognition, necessitating further examination.