Your sleep habits reveal more about your brain health than you might think. While lack of sleep is widely known to impact mood, cause fatigue, and even lead to long-term brain damage, what about regularly sleeping in? It's not as beneficial as you might assume, and new research suggests it may be an even bigger red flag.
In a recent study, researchers examined the impact of both regular short sleep and sleep-ins on the human brain and found that while consistently getting too little sleep is linked to depression and brain shrinkage in emotional regions, regularly sleeping too much may be an early warning sign of cognitive decline, Alzheimer's, or even schizophrenia.
"This study represents a paradigm shift in how we understand the relationship between sleep and health. Short sleep is often an underlying cause of health issues, whereas long sleep tends to reflect pre-existing conditions. These findings highlight the importance of personalized interventions to address the unique biological pathways of short and long sleepers," said researcher Professor Jianfeng Feng from The University of Warwick who led the study.
To uncover the link, researchers asked nearly half a million adults aged 38 to 73 from the UK Biobank database, a simple question about the number of hours they get to sleep in a day. Based on their responses, participants were divided into two groups: "short sleepers" (those getting fewer than 7 hours) and "long sleepers" (those exceeding 7 hours).
They then analyzed participants' genetic data, brain imaging scans, and overall health outcomes to understand how sleep duration might shape brain function and long-term cognitive health.
Regular short-duration sleep was linked to psychological problems, such as low mood and fatigue, and poorer muscle and skeletal health. Brain scans showed that short sleepers have reduced brain matter in brain areas involved in emotion and raised the risk of conditions such as depression, heart disease, and obesity.
However, sleeping for too long was linked to cognitive decline, higher inflammation, and poorer metabolic health, lowering levels of "good' cholesterol. Brain scans showed brain matter loss in areas associated with memory and known risk areas for degenerative diseases such as Alzheimer's and schizophrenia. Researchers, however, noted that long sleep durations appear to be a symptom rather than a cause of these conditions.
Based on the study, researchers suggest that both long sleep and short sleep are two "biologically distinct" processes, with their own genetic associations.
"Our ultimate goal is to construct a comprehensive sleep health profile across the human lifespan, providing actionable insights for individuals at every stage of life," Professor Feng added.
