A group of studies, all conducted independently, have reached a similar sobering conclusion: Sleep problems -- including several common sleep difficulties faced by millions of people on a regular basis -- may, over time, lead to cognitive impairment and even dementia.
Four studies presented at the Alzheimer's Association International Conference investigated the possible relationship between sleep disorders and cognitive function among older adults. Each study looked at the question from a different angle, and used different methods to obtain results. The collective result? A watershed of information that some of our most common sleep troubles -- including sleep deprivation, oversleeping, daytime tiredness, and sleep-disordered breathing -- may play a significant role in cognitive decline as we age.
Sleeping Too Little -- Or Too Much -- Linked to Cognitive Decline
Researchers at Brigham and Women's Hospital in Boston used data from the Nurses' Health Study to examine risk factors for cognitive problems in older adults. The Nurses' Health Study is a landmark, long-running, and ongoing study of women's health, using information collected from thousands of nurse-participants.
To investigate the relationship between sleep and cognitive decline, researchers examined data from 15,263 women, all of whom were 70 years or older at the time of the first cognitive assessment. The women received follow-up cognitive tests every other year for the following six years. Participants were also asked to report their daily sleep patterns and habits. Researchers found that sleeping too little and sleeping too much were both associated with cognitive decline over time:
Sleep-Disordered Breathing May Increase Risk of Dementia
A study led by scientists at University of California San Francisco, also examined the relationship between cognitive function and sleep disorders among older women. In this study, researchers did not use self-reported information about sleep. Instead, they measured sleep quality and quantity among 1309 women ages 75 and older, over a period of several days. Researchers used polysomnography and wrist sensors to collect detailed data about physical changes that occurred during sleep -- including brain activity and breathing -- as well as information about rest and activity levels. Five years later, the women were given tests to measure their cognitive functioning. The results of this study showed a connection between disrupted sleep -- especially sleep-disordered breathing -- and diminished cognitive function:
A preliminary version of these results was published last year in the Journal of the American Medical Association.
Daytime Sleepiness May Be a Risk for Cognitive Impairment
An international group of researchers from INSERM and Stanford University used data from the Three-City Study to examine the effect of sleep on cognitive function among men and women age 65 and older. The study used self-reported sleep information from 4,894 adults, including details on trouble falling asleep and staying asleep, poor sleep quality, waking early, and daytime sleepiness. Participants were given cognitive assessments every two years over a 10-year period.
In contrast with some of the other findings on sleep and cognition presented at AAIC, researchers in this study did not find that sleep duration, or difficulty falling asleep and staying asleep, were associated with cognitive decline. They did find, however, that excessive daytime sleepiness was associated with diminishing cognitive function among these older adults.
Do Disruptions to Circadian Rhythms Lead to Dementia?
A fourth study examined a hypothesis related to Alzheimer's disease: that abnormal levels of a particular protein known as amyloid-beta contributes to dementia. Changes in the body's production and clearance of this protein are considered a bio-marker for Alzheimer's disease. Levels of amyloid-beta protein naturally change in the body over time, and also fluctuate within a 24-hour period, and we don't currently know a lot about why or how these natural cycles work. This limited understanding makes accurately measuring and tracking abnormalities more difficult.
Scientists at St. Louis' Washington University School of Medicine examined changes in amyloid-beta protein in relation to circadian rhythms, and found that the protein's daily fluctuations conform to circadian patterns, suggesting that disruptions to circadian rhythms -- which happen with age as well as with disordered sleep -- may affect the production and regulation of this protein linked to dementia.
This is a lot to digest. In the case of each study, there is more work to be done to establish a causal link between disrupted sleep and cognitive decline. We're still a long way from a real understanding about just how sleep affects cognitive function over the course of a lifetime, and how lack of sleep may contribute to the onset of dementia or other conditions involving cognitive impairment and decline. But such unanimity among the results of no fewer than four separate studies certainly feels like the sounding of an alarm.
Sweet Dreams,
Michael J. Breus, PhD
The Sleep Doctor™
www.thesleepdoctor.com
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Or so I thought...
Now what the bleep am I supposed to do?!
As we age our sleep patterns change if we are older and work every day naturally we'll be more tired than those who do not work. Working out/exercise is key and never fails, if you stick to a routine you will sleep well. Also as we age we must work at living peacefully and not stress-fully. When the mind is peaceful the body will follow.
central sleep apnea is caused by an underlying condition like parkinson's or alzheimer's.
therefore the lack of sleep is not causing dementia, dementia is causing lack of sleep.
dementia usually increases over a period of time and is not recognized in it's early stages as a contributing factor.
like voodoo to me. Waste of an article.
Tomario
our bodies in all ways, and being older I find working out hard during the day, leads to a good night
sleep. Time alone is important to resting the whole being, and leads also to a peaceful sleep. Watch
intake of foods or drinks that keep one up,,,and keep a schedule. What was that old adage....Early to bed and early to rise...healthy, weathly and wise.......THey didn't have T.V. or a lot of caffine.
One night I actually fell asleep at a traffic signal and slept about 20 min. The hallucination occurred on a Thurs night around 3am. I was 1 block from home. I stopped at a stop sign, then proceeded. When I reached the middle of the intersection, I saw a car's headlights and the grille work out my driver's side windows as that car T-boned me. But there was no car. I was actually surprised that there was no impact. My heart skipped a few beats.
Sleep deprivation can also lead to highly unstable thinking, including thoughts of suicide. I considered that a flick of the steering wheel on a stretch of road going downhill could put me right into a light pole... and then I could sleep.
One's rationality and reasoning is off through the day.... one's clarity of thought is non-existant... and after you've been up for about 6 hours you reach a point when you simply cannot keep the eyes open... and you can fall asleep on your feet.
caused by sleep apnea. Apnea equals oxygen deprivation, which in turn
stresses brain cells. Snoring also is not benign, it is dangerous over time.
This is not voodoo, it is fact. We need to run smoothly through 5 sleep
cycles, each serves a purpose in re-setting the brain on an electro-chemical
and cognitive, emotional level.
I agree, though, one size does not fit all in terms of total sleep time,
some folks require less or more based on age, metabolism, circadian rhythm.