A recent study conducted by researchers at The University of Texas Health Science Center at San Antonio (UT Health San Antonio) revealed that sleeping nine or more hours per night is linked to reduced cognitive performance. This effect is most pronounced among individuals experiencing symptoms of depression, indicating a potential interaction between sleep duration and mental health that may accelerate cognitive decline. The research underscores the increasingly recognised importance of sleep as a modifiable factor influencing brain function and overall neurological health.
The study analysed data from 1,853 individuals participating in the Framingham Heart Study, an ongoing, community-based cohort study supported by the U.S. National Heart, Lung, and Blood Institute. Participants were aged between 27 and 85, with an average age of 49.8 years, and were free from both dementia and a history of stroke. The Framingham study is renowned for its longitudinal cardiovascular and neurological health insights. It offers a robust platform for exploring the complex interplay between sleep, cognition, and psychiatric conditions such as depression.
Vanessa Young, MS, the study’s lead author and a clinical research project manager at UT Health San Antonio’s Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, highlighted a key observation: individuals who regularly slept for nine or more hours were more likely to report symptoms of depression. Young, who is also pursuing a PhD in Translational Science, suggested that sleep might represent a modifiable risk factor for cognitive decline, particularly in people grappling with depression. This insight could pave the way for more targeted interventions to preserve mental health through improved sleep regulation.
Published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association on 21 April, the study included collaborators from several international institutions, including Arizona State University, the University of Montreal, Hôpital du Sacré-Coeur de Montréal, Boston University, Monash University in Australia, and the Framingham Heart Study. The wide-ranging collaboration lends further credence to the study’s implications, suggesting a consensus across disciplines regarding the significant impact of sleep habits on cognitive outcomes.
Senior author Dr Sudha Seshadri, founding director of the Biggs Institute, noted that extended sleep durations were explicitly associated with poorer performance in various cognitive domains, including global cognition, memory, visuospatial abilities, and executive function. Importantly, these associations were strongest among those experiencing depressive symptoms, regardless of whether they were taking antidepressants. The findings add depth to existing literature, showing mixed results regarding the effects of long versus short sleep on mental performance. This study offers a more nuanced picture by integrating mental health status into the analysis.
Sleep has long been acknowledged as essential for brain health, yet the mechanisms by which its duration and quality influence cognitive ageing remain under active investigation. The current study adds to a body of research suggesting that deviations from the recommended 7 to 8 hours of nightly sleep may be detrimental, especially when accompanied by psychological stressors like depression. Sleep disturbances and depression frequently co-occur, with nearly 90% of those diagnosed with depression also reporting sleep-related difficulties. These co-morbidities may compound cognitive vulnerability, particularly during middle age and later life.
The researchers concluded that the relationship between prolonged sleep and cognitive deficits is amplified in individuals showing signs of depression, regardless of whether they are on antidepressant treatment. In contrast, those without depressive symptoms exhibited weaker associations, and no significant cognitive effects of sleep duration were found in participants using antidepressants but not experiencing depressive symptoms. The authors suggest that further large-scale, longitudinal studies are needed to untangle the directionality and causality of these associations. Nonetheless, their findings make a strong case for considering sleep habits — particularly in individuals with mood disorders — as a key component of strategies to preserve cognitive function and prevent age-related decline.
More information: Vanessa Young et al, Long sleep duration, cognitive performance, and the moderating role of depression: A cross-sectional analysis in the Framingham Heart Study, Alzheimer’s & Dementia. DOI: 10.1002/alz.70160
Journal information: Alzheimer’s & Dementia Provided by University of Texas Health Science Center at San Antonio
