Daytime Sleepiness and Doubled Dementia Risk in Older Adults

Daytime Sleepiness Linked to Doubled Dementia Risk in Women Over 80: New Study

San Francisco, CA – Increasing daytime sleepiness over a five-year period is associated with a doubled risk of developing dementia in women in their 80s, according to research published March 19, 2025, in Neurology^®, the medical journal of the American Academy of Neurology. While the study demonstrates a strong association, it does not prove that daytime sleepiness causes dementia.

“Sleep is essential for cognitive health, as it allows the brain to rest and rejuvenate, enhancing our ability to think clearly and remember facts,” explained study author Yue Leng, PhD, of the University of California, San francisco.”Though, little is known about how changes in sleep and cognition are connected over time and how these changes relate to dementia risk in the later decades of life. Our study found that sleep problems may be intertwined with cognitive aging and may serve as an early marker or risk factor for dementia in women in their 80s.”

The research followed 733 women with an average age of 83 who showed no signs of mild cognitive impairment or dementia at the study’s outset. Over the five-year period, 22% (164 participants) developed mild cognitive impairment, and 13% (93 participants) were diagnosed with dementia.

Participants wore wrist devices to continuously monitor their sleep and circadian rhythm patterns at the beginning and end of the study. Researchers analyzed changes in nighttime sleep duration and quality, daytime napping habits, and circadian rhythm stability.

The study revealed important sleep pattern changes in over half of the participants (56%). These changes categorized individuals into three groups:

Stable Sleep/Improvement (44%): Participants experienced consistent sleep patterns or slight improvements.
Declining Nighttime Sleep (35%): This group showed decreases in nighttime sleep quality and duration, coupled with moderate increases in napping and disrupted circadian rhythms.
Increasing Sleepiness (21%): Participants in this group exhibited increases in both daytime and nighttime sleep duration and quality, alongside worsening circadian rhythms.

analysis of dementia risk revealed a striking difference. Only 8% (25 participants) of the stable sleep group developed dementia, compared to 15% (39 participants) in the declining nighttime sleep group. However, the increasing sleepiness group experienced a significantly higher rate, with 19% (29 participants) developing dementia.

Even after accounting for factors like age, education, race, diabetes, and high blood pressure, the researchers found that women in the increasing sleepiness group had double* the risk of dementia compared to those with stable sleep patterns. Notably, no significant association was found within the declining nighttime sleep group.

“We observed that sleeping, napping and circadian rhythms can change dramatically over only five years for women in their 80s,” Leng stated. “This highlights the need for future studies to look at all aspects of daily sleep patterns to better understand how changes in these patterns over time can be linked to dementia risk.”

The study authors acknowledge a limitation: the participant pool was predominantly white, which limits the generalizability of the findings to more diverse populations.

The research was funded by the National Institutes of Health.

What lifestyle modifications can older adults implement to perhaps bolster cognitive reserve and mitigate the risk of dementia,given the link between daytime sleepiness and cognitive decline?

Understanding the Link Between Excessive Daytime sleepiness and Cognitive Decline

Excessive daytime sleepiness (EDS) in older adults isn’t just a sign of getting older; emerging research strongly suggests itS a critically important risk factor for dementia,potentially doubling the likelihood of developing the condition. This isn’t simply about feeling tired; it’s a complex physiological signal that warrants investigation. Understanding this connection is crucial for early detection and potential intervention. We’ll explore the science behind this link, the types of dementia most associated with EDS, and what steps can be taken to mitigate the risk. Terms like cognitive impairment, sleep disorders, and neurodegenerative diseases are all interconnected in this context.

How Daytime Sleepiness Impacts Brain Health

The relationship between sleep and brain health is bidirectional. Sleep isn’t just when the brain rests; it’s how the brain restores itself. During sleep, the glymphatic system clears metabolic waste products, including amyloid and tau proteins – hallmarks of Alzheimer’s disease.

Here’s how EDS disrupts this process:

Amyloid Beta Accumulation: Disrupted sleep patterns,leading to EDS,are linked to increased amyloid beta plaque buildup in the brain.

Tau Protein Spread: Similarly, EDS can accelerate the spread of tau tangles, another key indicator of neurodegeneration.

Synaptic dysfunction: Chronic sleep deprivation and EDS impair synaptic plasticity – the brain’s ability to form new connections – essential for learning and memory.

Inflammation: Poor sleep quality and EDS trigger systemic inflammation, which further damages brain cells.

Reduced Cerebral Blood Flow: Studies show that EDS can correlate with reduced blood flow to the brain, depriving neurons of vital oxygen and nutrients.

Which Types of Dementia are Most Strongly Linked to EDS?

While EDS appears to increase the risk of all types of dementia, certain forms show a notably strong association:

Alzheimer’s Disease: The most common form of dementia, Alzheimer’s, is heavily linked to amyloid and tau pathology, both impacted by sleep disturbances. Research indicates that individuals experiencing chronic excessive sleepiness years before clinical diagnosis of Alzheimer’s have a considerably higher risk.

Vascular Dementia: Caused by reduced blood flow to the brain, vascular dementia is exacerbated by conditions often associated with EDS, such as hypertension and sleep apnea. Sleep apnea is a major contributor to vascular dementia risk.

Dementia with lewy Bodies (DLB): This type of dementia, characterized by abnormal protein deposits called Lewy bodies, is often accompanied by REM sleep behavior disorder (RBD) – a sleep disorder where individuals act out their dreams – and EDS.

Frontotemporal Dementia (FTD): While less common, FTD can also present with sleep disturbances and EDS, particularly in certain subtypes.

Identifying Excessive daytime Sleepiness: Symptoms and Assessment

Recognizing EDS is the first step towards addressing the potential risk. Symptoms go beyond simply feeling tired. Look for:

frequent yawning and dozing: Falling asleep unintentionally during the day, even in quiet settings.

Difficulty staying awake: Struggling to remain alert during activities like reading or watching television.

Reduced alertness: Feeling foggy, sluggish, or having difficulty concentrating.

Impaired performance: Experiencing difficulties with memory, attention, and decision-making.

Unrefreshing sleep: Waking up feeling tired despite getting what seems like enough sleep.

Assessment Tools:

Epworth Sleepiness Scale (ESS): A self-assessment questionnaire to gauge your level of daytime sleepiness.

Polysomnography (Sleep Study): A comprehensive sleep study conducted in a lab to diagnose sleep disorders like sleep apnea.

Multiple Sleep Latency Test (MSLT): measures how quickly you fall asleep during the day, helping to diagnose narcolepsy and other causes of EDS.

Addressing Daytime Sleepiness: Prevention and Management

While the link between EDS and dementia is concerning, proactive steps can be taken to reduce risk and improve overall brain health.

Prioritize Sleep Hygiene: Establish a regular sleep schedule, create a relaxing bedtime routine, and ensure a dark, quiet, and cool sleep surroundings.

Treat Underlying Sleep Disorders: Address conditions like sleep apnea, restless legs syndrome, and insomnia. CPAP therapy for sleep apnea is particularly important.

Manage Chronic conditions: Effectively manage conditions like hypertension, diabetes, and heart disease, which can contribute to both EDS and dementia.

Regular Exercise: Physical activity promotes better sleep and improves cognitive function. aim for at least 150 minutes of moderate-intensity exercise per week.

Healthy Diet: A balanced diet rich in fruits, vegetables, and whole grains supports brain health.

Cognitive Stimulation: Engage in mentally stimulating activities like puzzles, reading, and learning new skills to maintain cognitive reserve.

Regular Medical Checkups: Discuss any concerns about daytime sleepiness with your doctor. Early detection and intervention are key.

The Role of Biomarkers and Future research

Ongoing research is focused on identifying biomarkers