SAEDNEWS: When we think of sleep, we usually associate it with health, restoration, and a clear mind. But can too much of a good thing become harmful? According to a recent study conducted by UT Health San Antonio, excessive sleep may actually impair brain function—especially in individuals showing signs of depression.
According to SAEDNEWS, This new research adds a nuanced layer to our understanding of sleep and its impact on cognitive health. While sleep deprivation is already known to have negative consequences for the brain, this study reveals that sleeping too much may be just as harmful.
The study was led by Dr. Sudha Seshadri, a senior researcher and director of the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases. Her team sought to explore the relationship between sleep duration and cognitive performance, particularly investigating how depression might influence this dynamic.
According to Dr. Seshadri, “Long sleep duration was associated with an overall decline in cognitive function, including weakened memory, visuospatial skills, and executive functioning. The connection was especially stronger among individuals exhibiting symptoms of depression, regardless of whether or not they were taking antidepressant medication.”
To gather data, the researchers analyzed the responses of 1,853 participants from the Framingham Heart Study—an ongoing, long-term cardiovascular research project based in the United States. Participants, with an average age of around 50, reported their typical nightly sleep duration and underwent standardized cognitive assessments. Importantly, none of them had been diagnosed with dementia or had suffered from a stroke.
Based on their self-reported sleep patterns, participants were divided into three groups:
Short sleepers: less than 6 hours per night
Moderate sleepers: between 6 and 9 hours per night
Long sleepers: more than 9 hours per night
Additionally, the study categorized participants into four subgroups based on their depression status and medication use:
No depression symptoms and no antidepressant use (control group)
Antidepressant use without depression symptoms
Depression symptoms without antidepressant use
Depression symptoms with antidepressant use
The most significant finding? Long sleep was strongly linked to reduced cognitive function—but predominantly in those with signs of depression.
Vanessa Young, another lead author of the paper, noted: “People who sleep excessively tend to show more depressive symptoms. Therefore, sleep could be a modifiable risk factor for cognitive decline in individuals with depression.”
While short sleep has long been known to contribute to mental fatigue and cognitive problems, this study highlights a less frequently discussed risk: sleeping too much, particularly for individuals already dealing with mental health issues like depression.
Although the study opens new discussions about the importance of balanced sleep, the researchers are careful to point out that no direct cause-and-effect relationship was established. The findings rely on self-reported sleep durations, which may be affected by memory inaccuracies. Furthermore, because the participant pool mainly consisted of white individuals, the findings might not be generalizable to more ethnically diverse populations.
Nonetheless, the results serve as an important reminder: more sleep doesn’t necessarily mean better brain health, especially if it coexists with untreated or poorly managed mental health conditions.
The full findings of this study have been published in the Alzheimer’s Association Journal.
Experts generally recommend 7–9 hours of sleep per night for adults, depending on individual needs. While occasional oversleeping isn’t typically harmful, chronic long-duration sleep—especially over 9 hours—shouldn’t be ignored, particularly if it’s accompanied by mood changes, fatigue, or cognitive fog.
For individuals experiencing depression, managing sleep may become a crucial part of a larger strategy to preserve cognitive health and overall well-being.
If you or someone you know is sleeping excessively and experiencing depressive symptoms, consider consulting a healthcare professional. Sometimes, what we think is “just sleep” could be a signal from the brain that something deeper needs attention.
