Excessive Sleeping in Dementia Explained
Understanding the Connection Between Sleep and Dementia
Sleep problems are common in people with dementia, and excessive daytime sleepiness is one of the most noticeable changes. Research shows that up to 50 percent of individuals with dementia experience decreased total sleep time and disrupted sleep patterns. However, what makes this particularly concerning is not just the amount of sleep people get at night, but how they feel and function during the day.
One of the key findings from recent research is that excessive daytime sleepiness, even when someone gets enough sleep at night, can be an early warning sign of dementia. A long-term study tracking more than 700 women for five years found that women who felt increasingly sleepy during the day or who took longer and more frequent naps were almost twice as likely to develop dementia as those whose sleep habits remained steady. This is especially important for people who have never been habitual nappers but suddenly find themselves needing frequent daytime rest.
Why Sleep Matters for Brain Health
To understand why excessive sleeping connects to dementia, it helps to know what happens in the brain during sleep. During deep sleep, the brain performs a critical cleaning function. The brain clears out harmful waste products, including beta-amyloid proteins that are associated with Alzheimer’s disease. This cleansing process, called the glymphatic system, helps keep the brain healthy and functioning optimally.
When sleep is disrupted or fragmented, these toxic proteins accumulate in the brain instead of being cleared away. Over time, this buildup can lead to brain damage and cognitive decline. Additionally, during sleep, nerve cells in the brain make new connections in a process called neuroplasticity. This rewiring helps the brain process information and maintain cognitive function.
The Difference Between Too Little Sleep and Too Much Sleep
Research has clearly established that too little sleep raises the risk of dementia. Adults need around 7 to 9 hours of quality sleep every night. Consistently sleeping less than six hours can impair cognitive performance and increase dementia risk. One study found that older people with insomnia have a 40 percent higher risk of dementia or mild cognitive impairment. Lack of sleep even sped up brain aging by three to four years.
However, the picture becomes more complex when looking at excessive sleep. It is unclear whether an increase in sleep duration at night is a direct risk factor for dementia. As people age, sleep patterns naturally change, with more disruption and awakening. Some people may need more sleep at night to compensate for poor sleep quality and instability, which may actually be better than getting too little sleep.
What Really Matters: Sleep Quality and Daytime Function
The more concerning issue is not necessarily how much someone sleeps at night, but how they feel and function during the day. Excessive daytime sleepiness despite sufficient sleep at night, along with increased frequency and duration of naps, has been associated with increased risk for dementia or accumulation of Alzheimer’s disease proteins in the brain.
This daytime sleepiness may signal several underlying problems. It could indicate poorer-quality sleep at night, even if the person is in bed for enough hours. It might also reflect dysfunction of brain regions related to wakefulness. Changes in sleep patterns can also be related to the body’s internal clock, known as the circadian rhythm. As people age, this rhythm becomes less responsive to environmental factors like light, darkness, mealtimes, and physical activity.
Sleep Problems in Different Types of Dementia
Sleep problems are particularly common in certain types of dementia. In dementia with Lewy bodies, poor sleep quality and excessive sleeping during the day are more common than in other types of dementia. People with this condition often experience vivid dreams and may shout out or move while asleep, which can further disrupt their rest and even cause injury.
How Sleep Apnea Affects Dementia Risk
Sleep apnea, a condition where breathing repeatedly stops and starts during sleep, deserves special attention because it significantly increases dementia risk. When someone has untreated sleep apnea, breathing pauses can lower oxygen levels during sleep. This lack of oxygen can harm multiple organs, including the brain.
Repeated drops in oxygen can injure brain cells, especially in areas involved in memory. Sleep apnea is also linked to changes in the brain’s small blood vessels, which may lead to tiny areas of bleeding or reduced blood flow associated with memory loss and cognitive decline. Additionally, because sleep apnea prevents deep sleep, the brain’s natural cleanup process does not work as effectively, allowing harmful proteins to build up over time.
Multiple studies show a strong link between untreated sleep apnea and a higher risk of all types of dementia, Alzheimer’s disease, and vascular cognitive decline. Common warning signs of sleep apnea include loud chronic snoring, pauses in breathing during sleep, snorting or gasping during the night, excessive daytime sleepiness, trouble concentrating, and morning headaches.
The Role of Insomnia and Sleep Disruption
Insomnia, or persistent difficulty in falling and staying asleep, also contributes to dementia risk. Insomnia raises stress hormone levels, damages neurons, and disrupts circadian rhythms. This negatively impacts memory, attention, and reasoning abilities, which are key cognitive domains affected in Alzheimer’s disease. Research has found that chronic symptoms of insomnia are a significant and independent risk factor for cognitive decline.
Sleep disruption in older adults with dementia becomes increasingly problematic as physical health worsens. Symptoms of anxiety and depression also contribute to sleep disruption. The most notable clinical change in sleep among older adults is an increase in the number of nighttime awakenings and lower sleep efficiency, which is the ratio of time actually spent asleep to time spent in bed.
What This Means for Early Detection
While research has not yet confirmed whether sleep disturbances cause dementia or whether dementia causes sleep disturbances, scientists believe continuous 24-hour monitoring of sleep-wake patterns could be a simple yet powerful tool for early detection. Changes in sleep patterns and excessive daytime sleepiness may serve as an early marker for cognitive decline, paving the way for more timely care and intervention.
For people concerned about their sleep or that of a loved one, paying attention to changes in daytime sleepiness, napping patterns, and overall sleep quality is important. These changes, especially when they represent a shift from previous habits, warrant discussion with a healthcare provider.
Sources
https://www.elderlawanswers.com/new-research-on-dementia-risk-factors-screenings-21360
