Sleep Fragmentation & Alzheimer’s Risk
Sleep quality — not just duration — may be one of the most underappreciated determinants of long-term cognitive health.
The Study
“Sleep Disruption and Amyloid Accumulation in Middle-Aged Adults”, published in JAMA Neurology, examined the relationship between sleep fragmentation and brain amyloid deposition — a hallmark of Alzheimer’s disease.
Why This Caught My Attention
We’ve long known that sleep matters for cognition. What makes this study particularly important is the finding that sleep fragmentation in middle age predicts amyloid accumulation — well before clinical cognitive decline becomes apparent.
This reframes Alzheimer’s disease as a process that begins decades earlier than we often acknowledge.
Key Findings
- Sleep fragmentation is associated with increased brain amyloid deposition
- This association persists even after controlling for total sleep time and sleep apnoea
- The effect appears stronger than sleep duration alone
- Middle age may represent a critical window for long-term brain health
The Mechanism
During deep sleep, the brain’s glymphatic system clears metabolic waste, including amyloid-beta. Sleep fragmentation reduces time spent in deep sleep and impairs this clearance process.
Over decades, impaired waste removal likely contributes to progressive amyloid accumulation and neurodegeneration.
Clinical Relevance
This isn’t limited to diagnosed sleep disorders. Many high-functioning professionals experience fragmented sleep due to:
- Chronic stress or anxiety
- Late-night eating or alcohol use
- Poor sleep hygiene
- Excessive electronic device exposure
These individuals may log “enough” hours but still experience poor-quality sleep.
Surgical Angle
Post-operative cognitive dysfunction is more common in patients with pre-existing sleep disturbances. Sleep fragmentation may reduce cognitive reserve, making the brain more vulnerable to surgical stress and anaesthesia.
Assessment & Intervention
- Track sleep quality — not just duration — using wearable devices
- Screen for sleep apnoea when indicated (home sleep study if appropriate)
- Optimize evening routines and stress management
- Eliminate late-night eating and alcohol
- Optimize bedroom environment (light, noise, temperature)
- Consider magnesium or other sleep aids when appropriate
My Protocol: I now assess sleep quality in all longevity consultations. For patients with fragmented sleep, this becomes a top priority — often more important than supplements or advanced interventions. The brain’s waste-clearance system only works well during high-quality sleep.
BOTTOM LINE
Sleep fragmentation is a modifiable risk factor for cognitive decline. Middle age is the time to fix it — not retirement. This is preventive neurology at its most practical.