Sleep is essential for human health. Not getting enough sleep or having poor, fragmented sleep increases a person's risk of developing many chronic illnesses, including cardiovascular disease and type 2 diabetes. With nearly one-third of all adults in the United States reporting that they are sleep-deprived, the importance of getting a good night's sleep takes on tremendous significance.

Illuminating the risks associated with inadequate sleep

Brain scans show that as amyloid-beta protein accumulates in the prefrontal cortex (an area responsible for memory consolidation and decision making) slow-wave, NREM sleep is impaired.

New research has identified associations between poor sleep and increased risk for Alzheimer's disease and related dementias. More than 2,800 older adults participated in the study. They completed questionnaires about their sleep quality, including how long it took them to fall asleep, how long they slept, and whether they snored. The study investigators collected information about the participants' cognitive health or if they died from any cause during a period of five years after completion of the questionnaires.

The findings revealed that participants who reported getting fewer than five hours of sleep per night were twice as likely to develop dementia compared to those who had seven to eight hours of sleep per night. Taking a long time to fall asleep (more than 30 minutes) increased the risk of dementia 45 percent. The authors also found that getting fewer than five hours of sleep per night, having daytime sleepiness, and taking regular naps increased the risk of all causes of premature death.

Episode highlights

• 00:00:00
  Introduction
• 00:00:14
  Sleep and dementia
• 00:01:27
  Glymphatic system cleans the brain
• 00:02:19
  Dr. Matthew Walker Clip
• 00:03:06
  Omega-3 fatty acids
• 00:03:19
  Exercise
• 00:03:52
  Sleep tips
• 00:04:36
  Subscribe

The connection between poor sleep and dementia

"Poor sleep promotes the build-up of amyloid-beta, which, in turn, promotes poor sleep, creating a feedback that has direct effects on brain health."- Dr. Rhonda Patrick Click To Tweet

This episode was fiscally sponsored through The Film Collaborative and a grant from a generous anonymous donor.

What's driving the links between sleep and dementia?

Sleep – especially deep, or slow-wave, sleep – activates the glymphatic system, a vast arrangement of fluid-filled cavities that facilitate the removal of toxic waste products and other cellular debris from the central nervous system. One of these toxic products is amyloid-beta, a protein that aggregates and forms plaques in the brain – one of the hallmarks of Alzheimer's disease. But during deep sleep, the glymphatic system actively clears nearly half of the total amyloid-beta accumulation.

Although scientists have identified other lifestyle behaviors that can help prevent the build-up of amyloid plaques by boosting the capacity for glymphatic clearance – such as exercise and adequate intake of omega-3 – the most important factor by far is a good night's sleep, especially deep sleep.

Making sleep a priority is essential to maintaining long-term cognitive health.

• To learn more about how sleep affects cognitive health, check out our episode featuring sleep expert Dr. Matthew Walker.

Relevant work

• Prefrontal atrophy, disrupted NREM slow waves and impaired hippocampal-dependent memory in aging

• Sleep drives metabolite clearance from the adult brain

• Omega-3 polyunsaturated fatty acids promote amyloid-β clearance from the brain through mediating the function of the glymphatic system