What is the “just right” amount of sleep? No doubt you know someone who brags about “getting by” on five or less hours per night. Maybe you’re the one doing the bragging. Unfortunately, medical evidence overwhelmingly suggests that anyone who believes they can get by on so little sleep is kidding themselves. There’s an optimal amount, and getting anything less can lead to serious health consequences. So what is the “Goldilocks” of “just-right” sleep requirements? Well, one new study doesn’t just offer some clear answers to that question. It also reveals a surprising link between getting too much or too little sleep and an increased risk for Alzheimer’s disease.
The Need For Sleep
Sleep is an essential component to good health –– as vital as a healthy diet, clean air, and regular exercise. Everyone’s sleep requirements are different, but, in general, if you wake up refreshed and ready to tackle the day, chances are you’ve enjoyed some quality slumber. If you’re an adult, then that generally means a bit more than seven hours per night.
Sleep is when our body repairs itself, and when we can recover mentally from the day’s events. During a healthy sleep session, we will enter the rapid-eye-movement (REM) stage where we are in deep, dream-filled sleep three or four times. Getting both REM sleep and non-REM sleep is necessary for succeeding during the day because without it you’ll have trouble processing and retaining information. When you get less than seven hours per night, you likely don’t complete the three or four cycles that you need –– which is like pulling your car from the mechanic shop before repair work is complete. Research shows that getting inadequate sleep can lead to heart disease, obesity, and depression while increasing the severity of migraines and your risk of infection. Now a recent study suggests inadequate sleep can lead to Alzheimer’s disease, a progressive, incurable disorder.
According to the Alzheimer’s Association, nearly 12% of people over the age of 65 suffer from the condition which kills more people than breast cancer and prostate cancer combined. Not only have death rates from Alzheimer’s disease been rising for years, but they have increased by more than 16% since the COVID-19 pandemic. One early marker for the condition is amyloid β (Aβ), a protein which is vital for memory and understanding. However, in patients with dementia, the protein accumulates in the cerebral cortex and forms plaques. Currently, there is no treatment for this condition.
However, in undertaking a study of some 4,000 adults, researchers proposed that sleep habits could be connected to amyloid β (Aβ) accumulation. Cognitively unimpaired adults were recruited across 67 different sites in the United States, Canada, Australia, and Japan. They were confirmed to have no signs of dementia. They each self-reported their sleep habits while their brains were examined for the accumulation of amyloid-β using a positron emission tomography (PET) scan.
The study showed that participants who slept less than six hours a night had more of the marker as did those who consistently had more than nine. Seven to nine hours is the Goldilocks of sleep. The study also showed that getting extra sleep outside the natural circadian rhythm doesn’t alter accumulation of the marker. This suggests that we can’t “catch up” with an afternoon nap –– at least as far as this protein is concerned. Although there are many provable, beneficial reasons to take a nap, reducing your amyloid-β burden and thus your increased risk for developing dementia years or even decades later isn’t one of them.
If you’re struggling with getting enough sleep, there are steps to take. Keep a regular bedtime and limit alcohol, caffeine, and your use of blue-light emitting electronic devices in the hours before you plan to go to sleep. Most importantly, start getting a good night’s sleep as if your life depends upon it–because research suggests it really does.
Written by John Bankston
- Sleeping hours: what is the ideal number and how does age impact this?
- The Science of Sleep: Understanding What Happens When You Sleep
- Alzheimer’s Disease Facts and Figures
- The Amyloid-β Pathway in Alzheimer’s Disease
- Association of Sleep and β-Amyloid Pathology Among Older Cognitively Unimpaired Adults