We often hear that sleep is important for our physical and mental health - but what if it also plays a key role in protecting our brain from dementia? Mounting research suggests that how well - and how long - we sleep in midlife and beyond may have a lasting impact on our risk of developing cognitive decline later in life.

From the National Institutes of Health to leading sleep researchers at Harvard and Alzheimer’s UK, the consensus is growing: sleep isn’t just rest - it’s brain maintenance.

Let’s explore the science behind the connection and what it means for long-term brain health.

Sleep and Dementia: What’s the Link?

During sleep, your brain clears waste, consolidates memories, and resets neural networks. One of the key substances cleared during deep sleep is beta-amyloid - the same protein that builds up in the brains of people with Alzheimer’s disease.

In a major study from the NIH, people in their 50s and 60s who regularly slept fewer than six hours per night had a significantly higher risk of developing dementia later in life. The study followed more than 7,900 participants over 25 years and found a clear association between sleep deprivation in midlife and future cognitive decline.
👉 NIH summary here

How Much Sleep Is Enough?

Most adults need seven to nine hours of quality sleep per night. But it’s not just quantity - sleep quality matters too. Disruptions like insomnia, sleep apnea, or frequent nighttime waking can all interfere with the brain’s housekeeping processes.

A 2024 study published in Psychiatry Research showed that short sleep duration under 7 hours was associated with higher risk of Alzheimer’s disease among older adults, especially when combined with poor sleep quality and comorbid health issues.
👉 View study on ScienceDirect

Harvard’s Take: Sleep as a Dementia Prevention Strategy

According to Harvard Health, chronic sleep loss and poor sleep quality are both linked to increased levels of tau and amyloid proteins - key biomarkers of Alzheimer’s. They recommend simple sleep hygiene strategies, including:

• Keeping a consistent bedtime

• Avoiding caffeine and alcohol late in the day

• Limiting screen time before bed

• Creating a quiet, cool, dark sleep environment

👉 Read more from Harvard Health

What About People Already Living with Dementia?

Sleep problems are common in people with dementia, and they can worsen symptoms such as confusion, agitation, and memory loss. According to Alzheimer’s Society UK, supporting better sleep can help manage symptoms and improve quality of life.

Their recommendations include creating a calming bedtime routine, avoiding long daytime naps, and ensuring exposure to natural daylight to regulate circadian rhythms.
👉 See Alzheimer’s Society UK guidance

How Elli Cares Supports Sleep and Brain Health

The Elli Cares app helps people living with dementia - and those who care for them - create predictable, calming daily routines. Features like:

• Bedtime reminders

• Medication tracking

• Hydration and symptom logging

• Mood and energy check-ins

…can all support healthy sleep habits. Families can stay informed and gently encourage restful routines, helping reduce stress and improve sleep over time.

👉 Learn more at www.elliapp.co

Final Thoughts

Poor sleep doesn’t just leave us tired - it may leave the brain vulnerable. While more research is still underway, one message is clear: getting enough good-quality sleep is one of the most powerful things we can do to protect our brains as we age.

For those at risk - or caring for someone who is - supporting sleep is more than self-care. It’s a strategy for long-term cognitive health and dementia prevention.