Study: Too Little and Too Much Sleep Linked to Cognitive Decline

Tamara Bhandari wrote . . . . . . . . .

Like so many other good things in life, sleep is best in moderation. A multiyear study of older adults found that both short and long sleepers experienced greater cognitive decline than people who slept a moderate amount, even when the effects of early Alzheimer’s disease were taken into account. The study was led by researchers at Washington University School of Medicine in St. Louis.

Poor sleep and Alzheimer’s disease are both associated with cognitive decline, and separating out the effects of each has proven challenging. By tracking cognitive function in a large group of older adults over several years and analyzing it against levels of Alzheimer’s-related proteins and measures of brain activity during sleep, the researchers generated crucial data that help untangle the complicated relationship among sleep, Alzheimer’s and cognitive function. The findings could aid efforts to help keep people’s minds sharp as they age.

The findings are published in the journal Brain.

“It’s been challenging to determine how sleep and different stages of Alzheimer’s disease are related, but that’s what you need to know to start designing interventions,” said first author Brendan Lucey, MD, an associate professor of neurology and director of the Washington University Sleep Medicine Center. “Our study suggests that there is a middle range, or ‘sweet spot,’ for total sleep time where cognitive performance was stable over time. Short and long sleep times were associated with worse cognitive performance, perhaps due to insufficient sleep or poor sleep quality. An unanswered question is if we can intervene to improve sleep, such as increasing sleep time for short sleepers by an hour or so, would that have a positive effect on their cognitive performance so they no longer decline? We need more longitudinal data to answer this question.”

Alzheimer’s is the main cause of cognitive decline in older adults, contributing to about 70% of dementia cases. Poor sleep is a common symptom of the disease and a driving force that can accelerate the disease’s progression. Studies have shown that self-reported short and long sleepers are both more likely to perform poorly on cognitive tests, but such sleep studies typically do not include assessments of Alzheimer’s disease.

To tease apart the separate effects of sleep and Alzheimer’s disease on cognition, Lucey and colleagues turned to volunteers who participate in Alzheimer’s studies through the university’s Charles F. and Joanne Knight Alzheimer Disease Research Center. Such volunteers undergo annual clinical and cognitive assessments, and provide a blood sample to be tested for the high-risk Alzheimer’s genetic variant APOE4. For this study, the participants also provided samples of cerebrospinal fluid to measure levels of Alzheimer’s proteins, and each slept with a tiny electroencephalogram (EEG) monitor strapped to their foreheads for four to six nights to measure brain activity during sleep.

In total, the researchers obtained sleep and Alzheimer’s data on 100 participants whose cognitive function had been monitored for an average of 4 1/2 years. Most (88) had no cognitive impairments, 11 were very mildly impaired, and one had mild cognitive impairment. The average age was 75 at the time of the sleep study.

The researchers found a U-shaped relationship between sleep and cognitive decline. Overall, cognitive scores declined for the groups that slept less than 4.5 or more than 6.5 hours per night — as measured by EEG — while scores stayed stable for those in the middle of the range. EEG tends to yield estimates of sleep time that are about an hour shorter than self-reported sleep time, so the findings correspond to 5.5 to 7.5 hours of self-reported sleep, Lucey said.

The U-shaped relationship held true for measures of specific sleep phases, including rapid-eye movement (REM), or dreaming, sleep; and non-REM sleep. Moreover, the relationship held even after adjusting for factors that can affect both sleep and cognition, such as age, sex, levels of Alzheimer’s proteins, and the presence of APOE4.

“It was particularly interesting to see that not only those with short amounts of sleep but also those with long amounts of sleep had more cognitive decline,” said co-senior author David Holtzman, MD, a professor of neurology. “It suggests that sleep quality may be key, as opposed to simply total sleep.”

Each person’s sleep needs are unique, and people who wake up feeling rested on short or long sleep schedules should not feel compelled to change their habits, Lucey said. But those who are not sleeping well should be aware that sleep problems often can be treated.

“I ask many of my patients, ‘How’s your sleep?’” said co-senior author Beau M. Ances, MD, PhD, the Daniel J. Brennan, MD, Professor of Neurology. Ances treats patients with dementia and other neurodegenerative conditions at Barnes-Jewish Hospital. “Often patients report that they’re not sleeping well. Often once their sleep issues are treated, they may have improvements in cognition. Physicians who are seeing patients with cognitive complaints should ask them about their quality of sleep. This is potentially a modifiable factor.”

Source: Washington University School of Medicine

New Mothers’ Sleep Loss Linked to Accelerated Aging

Stuart Wolpert wrote . . . . . . . . .

When new mothers complain that all those sleepless nights caring for their newborns are taking years off their life, they just might be right, UCLA research published this summer in the journal Sleep Health suggests.

Scientists studied 33 mothers during their pregnancies and the first year of their babies’ lives, analyzing the women’s DNA from blood samples to determine their “biological age,” which can differ from chronological age. They found that a year after giving birth, the biological age of mothers who slept less than seven hours a night at the six-month mark was three to seven years older than those who logged seven hours or more.

Mothers who slept less than seven hours also had shorter telomeres in their white blood cells. These small pieces of DNA at the ends of chromosomes act as protective caps, like the plastic tips on the ends of shoelaces. Shortened telomeres have been linked to a higher risk of cancers, cardiovascular and other diseases, and earlier death.

“The early months of postpartum sleep deprivation could have a lasting effect on physical health,” said the study’s first author, Judith Carroll, UCLA’s George F. Solomon Professor of Psychobiology. “We know from a large body of research that sleeping less than seven hours a night is detrimental to health and increases the risk of age-related diseases.”

While participants’ nightly sleep ranged from five to nine hours, more than half were getting less than seven hours, both six months and one year after giving birth, the researchers report.

“We found that with every hour of additional sleep, the mother’s biological age was younger,” said Carroll, a member of the Cousins Center for Psychoneuroimmunology at UCLA’s Jane and Terry Semel Institute for Neuroscience and Human Behavior. “I, and many other sleep scientists, consider sleep health to be just as vital to overall health as diet and exercise.”

Carroll urged new mothers take advantage of opportunities to get a little extra sleep, like taking naps during the day when their baby is asleep, accepting offers of assistance from family and friends, and, when possible, asking their partner to help with the baby during the night or early morning. “Taking care of your sleep needs will help you and your baby in the long run,” she said.

Co-author Christine Dunkel Schetter, a distinguished professor of psychology and psychiatry at UCLA, said the study results “and other findings on maternal postpartum mental health provide impetus for better supporting mothers of young infants so that they can get sufficient sleep — possibly through parental leave so that both parents can bear some of the burden of care, and through programs for families and fathers.”

Dunkel Schetter added that while accelerated biological aging linked to sleep loss may increase women’s health risks, it doesn’t automatically cause harm to their bodies. “We don’t want the message to be that mothers are permanently damaged by infant care and loss of sleep,” she emphasized. “We don’t know if these effects are long lasting.”

‘This aisle is closed’: Using epigenetics to determine biological age

The study used the latest scientific methods of analyzing changes in DNA to assess biological aging — also known as epigenetic aging, Dunkel Schetter said. DNA provides the code for making proteins, which carry out many functions in the cells of our body, and epigenetics focuses on whether regions of this code are “open” or “closed.”

“You can think of DNA as a grocery store,” Carroll said, “with lots of basic ingredients to build a meal. If there is a spill in one aisle, it may be closed, and you can’t get an item from that aisle, which might prevent you from making a recipe. When access to DNA code is ‘closed,’ then those genes that code for specific proteins cannot be expressed and are therefore turned off.”

Because specific sites within DNA are turned on or off with aging, the process acts as a sort of clock, Carroll said, allowing scientists to estimate individuals’ biological age. The greater an individual’s biological, or epigenetic, age, the greater their risk of disease and earlier death.

The study’s cohort — which included women who ranged in age from 23 to 45 six months after giving birth — is not a large representative sample of women, the authors said, and more studies are needed to better understand the long-term impact of sleep loss on new mothers, what other factors might contribute to sleep loss and whether the biological aging effects are permanent or reversible.

Source: UCLA

Sleep, Exercise & Your Odds for a Long, Healthy Life

Denise Mann wrote . . . . . . . . .

Poor quality sleep can shave years off your life, and these effects may be magnified if you don’t get enough physical activity.

That’s the bad news. The good news is that getting more exercise may help counter some of the health risks known to accompany poor quality sleep, new research shows.

Folks who scored low in both sleep and exercise categories were 57% more likely to die from heart disease, stroke and cancer over more than a decade of follow-up when compared with those who reported getting better sleep and more exercise.

“Physical inactivity seems to amplify the health risks of poor sleep patterns in a synergistic way,” said study co-author Emmanuel Stamatakis.

“The mortality risk from physical inactivity and poor sleep combined is larger than the sum of the separate risks of poor sleep and physical inactivity,” added Stamatakis, a professor of physical activity, lifestyle and population health at the University of Sydney in Australia.

But getting at least 150 minutes of moderate or 75 minutes of vigorous exercise each week seems to dampen these effects, he said.

The study wasn’t designed to say how, or even if, poor sleep and lack of exercise work together, but researchers do have their theories.

Many sleep problems, such as short sleep or insomnia, cause hormonal and metabolic dysfunction and inflammation, and stimulate the sympathetic nervous system, Stamatakis explained. When the sympathetic nervous system is activated, it triggers the release of stress hormones that can increase heart rate and blood pressure, which can raise your risk for heart disease over time.

Physical activity works on the same pathways but in the opposite direction, Stamatakis said. “A possible explanation is that regular activity helps neutralize some of these consequences of poor sleep,” he noted.

For the study, the researchers analyzed information from more than 380,000 middle-aged men and women who took part in the large-scale U.K. Biobank study.

People were given a sleep score of 0 to 5 based on several factors, including whether they typically got seven to eight hours of sleep a night, had insomnia regularly, snored, felt tired during the day, or were a “night owl” or “morning lark.”

The sleep score was combined with a high, medium or low physical activity score, and people were categorized based on different combinations of sleep and exercise scores.

The lower the sleep score, the higher the risks of death from any cause during the 11-year follow-up. Exercise, however, blunted some of these effects.

“For someone who moves very little in general, I would advise them to introduce small amounts of physical activity of about 10-15 minutes per day that can comfortably fit into their daily routine and work towards 25-30 minutes per day over time,” Stamatakis said.

There will be spillover benefits on your sleep, too. “Physical activity improves sleep quality so they will enjoy the direct benefits of physical activity/exercise and may receive some help with their sleep problems,” Stamatakis said.

The study had its share of limitations. Folks only provided information on their sleep and physical activity at one point in time so researchers can’t know whether these habits changed with time.

The findings appear in the British Journal of Sports Medicine.

“If you are having trouble sleeping, but still manage to exercise regularly, you are in a better place than someone who is not exercising and having sleep problems,” said Dr. Martha Gulati, editor-in-chief of CardioSmart.org, the American College of Cardiology’s educational site for patients.

“This is the first study I have seen that looked at how sleep and exercise interact,” said Gulati, who has no ties to the new research. “There appears to be a synergy between the two, but more research is needed to tease out exactly how sleep and exercise work together to affect health.”

If you are not sleeping enough, you may be too tired to exercise, she said. It’s also possible that an underlying medical condition may be affecting your sleep.

Source: HealthDay

Having Trouble Falling Asleep Predicts Cognitive Impairment in Later Life

A study of nearly 2,500 adults found that having trouble falling asleep, as compared to other patterns of insomnia, was the main insomnia symptom that predicted cognitive impairment 14 years later.

Results show that having trouble falling asleep in 2002 was associated with cognitive impairment in 2016. Specifically, more frequent trouble falling asleep predicted poorer episodic memory, executive function, language, processing speed, and visuospatial performance. Further analysis found that associations between sleep initiation and later cognition were partially explained by both depressive symptoms and vascular diseases in 2014 for all domains except episodic memory, which was only partially explained by depressive symptoms.

“While there is growing evidence for a link between insomnia and cognitive impairment in older adults, it has been difficult to interpret the nature of these associations given how differently both insomnia and cognitive impairment can present across individuals,” said lead author Afsara Zaheed, a graduate student in clinical science within the department of psychology at the University of Michigan. “By investigating associations between specific insomnia complaints and cognition over time using strong measures of cognitive ability, we hoped to gain additional clarity on whether and how these different sleep problems may lead to poor cognitive outcomes.”

Insomnia involves difficulty falling asleep or staying asleep, or regularly waking up earlier than desired, despite allowing enough time in bed for sleep. Daytime symptoms include fatigue or sleepiness; feeling dissatisfied with sleep; having trouble concentrating; feeling depressed, anxious, or irritable; and having low motivation or energy.

The study analyzed data from the Health and Retirement Study, which involved 2,496 adults who were at least 51 years of age. In 2002 they reported the frequency of experiencing insomnia symptoms. In 2016 the participants’ cognition was assessed as part of the Harmonized Cognitive Assessment Protocol and operationalized with a comprehensive neuropsychological battery tapping episodic memory, executive function, language, visuoconstruction, and processing speed. Analyses controlled for sociodemographics and baseline global cognitive performance.

“These results are important given the lack of currently available treatments for late-life cognitive disorders, like Alzheimer’s disease and other dementias,” said Zaheed. “Sleep health and sleep behaviors are often modifiable. These results suggest that regular screening for insomnia symptoms may help with tracking and identifying people with trouble falling asleep in mid-to-late life who might be at risk for developing cognitive impairments later in life. Additional intervention research is needed to determine whether intervening on insomnia symptoms can help prevent or slow the progression of cognitive impairments in later life.”

The research abstract was published recently in an online supplement of the journal Sleep and will be presented as a poster beginning June 9 during Virtual SLEEP 2021. SLEEP is the annual meeting of the Associated Professional Sleep Societies, a joint venture of the American Academy of Sleep Medicine and the Sleep Research Society.

Source: Sleep 2021

Researcher Finds “Earworms” After Listening to Music Near Bedtime Continue During Sleep

Most people listen to music throughout their day and often near bedtime to wind down. But can that actually cause your sleep to suffer? When sleep researcher Michael Scullin, Ph.D., associate professor of psychology and neuroscience at Baylor University, realized he was waking in the middle of the night with a song stuck in his head, he saw an opportunity to study how music — and particularly stuck songs — might affect sleep patterns.

Scullin’s recent study, published in Psychological Science, investigated the relationship between music listening and sleep, focusing on a rarely-explored mechanism: involuntary musical imagery, or “earworms,” when a song or tune replays over and over in a person’s mind. These commonly happen while awake, but Scullin found that they also can happen while trying to sleep.

“Our brains continue to process music even when none is playing, including apparently while we are asleep,” Scullin said. “Everyone knows that music listening feels good. Adolescents and young adults routinely listen to music near bedtime. But sometimes you can have too much of a good thing. The more you listen to music, the more likely you are to catch an earworm that won’t go away at bedtime. When that happens, chances are your sleep is going to suffer.”

People who experience earworms regularly at night — one or more times per week — are six times as likely to have poor sleep quality compared to people who rarely experience earworms. Surprisingly, the study found that some instrumental music is more likely to lead to earworms and disrupt sleep quality than lyrical music.

The study involved a survey and a laboratory experiment. The survey involved 209 participants who completed a series of surveys on sleep quality, music listening habits and earworm frequency, including how often they experienced an earworm while trying to fall asleep, waking up in the middle of the night and immediately upon waking in the morning.

In the experimental study, 50 participants were brought into Scullin’s Sleep Neuroscience and Cognition Laboratory at Baylor, where the research team attempted to induce earworms to determine how it affected sleep quality. Polysomnography — a comprehensive test and the gold standard measurement for sleep — was used to record the participants’ brain waves, heart rate, breathing and more while they slept.

“Before bedtime, we played three popular and catchy songs — Taylor Swift’s ‘Shake It Off,’ Carly Rae Jepsen’s ‘Call Me Maybe’ and Journey’s ‘Don’t Stop Believin’,” Scullin said. “We randomly assigned participants to listen to the original versions of those songs or the de-lyricized instrumental versions of the songs. Participants responded whether and when they experienced an earworm. Then we analyzed whether that impacted their nighttime sleep physiology. People who caught an earworm had greater difficulty falling asleep, more nighttime awakenings, and spent more time in light stages of sleep.”

Additionally, EEG readings — records of electrical activity in the brain — from the experimental study were quantitatively analyzed to examine physiological markers of sleep-dependent memory consolidation. Memory consolidation is the process by which temporary memories are spontaneously reactived during sleep and transformed into a more long-term form.

“We thought that people would have earworms at bedtime when they were trying to fall asleep, but we certainly didn’t know that people would report regularly waking up from sleep with an earworm. But we saw that in both the survey and experimental study,” he said.

Participants who had a sleep earworm showed more slow oscillations during sleep, a marker of memory reactivation. The increase in slow oscillations was dominant over the region corresponding to the primary auditory cortex which is implicated in earworm processing when people are awake.

“Almost everyone thought music improves their sleep, but we found those who listened to more music slept worse,” Scullin said. “What was really surprising was that instrumental music led to worse sleep quality — instrumental music leads to about twice as many earworms.”

The study found that individuals with greater music listening habits experienced persistent earworms and a decline in sleep quality. These results are contrary to the idea of music as a hypnotic that might help sleep. Health organizations commonly recommend listening to quiet music before bedtime — recommendations that largely arise from self-reported studies. Instead, Scullin has objectively measured that the sleeping brain continues to process music for several hours, even after the music stops.

Knowing that earworms negatively affect sleep, Scullin recommends first trying to moderate music listening or taking occasional breaks if bothered by earworms. Timing of music also is important — try to avoid it before bed.

“If you commonly pair listening to music while being in bed, then you’ll have that association where being in that context might trigger an earworm even when you’re not listening to music, such as when you’re trying to fall asleep,” he said.

Another way to get rid of an earworm is to engage in cognitive activity — fully focusing on a task, problem or activity helps to distract your brain from earworms. A previous study by Scullin — partially funded by a National Institutes of Health grant and the Sleep Research Society Foundation — found that participants who took five minutes to write down upcoming tasks before bed helped “offload” those worrying thoughts about the future and led to faster sleep.

Source: Baylor University