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Spokane, Washington  Est. May 19, 1883

Study finds regularity with sleep length deters cognitive decline, but don’t stress over it

A new study adds a twist to how much sleep boosts our health.

Researchers found that consistently sleeping seven hours or more a night over the years – even at midlife when people are at their busiest building careers and raising families – can deter cognitive decline later in life.

Older adults who slept with uneven sleep patterns that included less than seven hours at night during a 20-year span were more likely to develop cognitive decline, the study said, compared with those who regularly slept at least seven hours a night.

The study also found that people whose sleep changed the most year-to-year had more than a threefold increased risk of cognitive impairment.

“Making sure that good sleep is a regular part of your life – not just on weekends and not just on vacations – is important,” said Jeffrey Iliff, a University of Washington School of Medicine professor who led the study. He said people should strive for sleep consistency.

The study followed 826 older adults who had no cognitive decline signs when they enrolled nearly two decades ago. They reported on how long they slept the previous seven days during the project. The adults took a series of cognitive function assessments over time.

Two Washington State University professors who do sleep-health research agree that adults should target those seven hours or more of sleep consistently. They’re familiar with the study, as Iliff recently spoke at the WSU Sleep and Performance Center in Spokane.

Hans Van Dongen, the center’s director, said sleep supports physical and brain health. Regularity of sleep helps, too.

“This study just confirms something we’ve known for a long time,” he said. “We know when you don’t get enough sleep, there is accumulation of what we can describe as waste from the brain that doesn’t properly get cleared, because there isn’t enough time to get rid of it, so there is a buildup of that waste.

“We know if you did sleep seven hours on average on a regular basis, you would probably clear the waste from the brain and take care of everything the brain needs to do during sleep.”

People should aim for that sleep pattern even in their 30s and 40s, said Jason Gerstner, an Elson S. Floyd College of Medicine associate professor.

Gerstner works in a research group that has studied fruit flies to understand sleep mechanisms and how sleep loss might play a role toward beta-amyloid buildup.

Many researchers believe sleep plays a role in clearing a sticky substance called beta-amyloid in the brain that can gradually build up into plaques. Plaques and tangles tend to spread through the cortex in a predictable pattern as Alzheimer’s progresses, the Alzheimer’s Association says.

Gerstner helped generate physiological characteristics similar to Alzheimer’s in fruit flies, in studying whether increasing sleep would improve the Alzheimer’s flies that carry toxic beta amyloid molecules.

“The idea here is that there is this reciprocal relationship that we believe occurs between our sleep-wake system and the ability of these toxic molecules to be cleared from the brain,” Gerstner said.

Toxic buildup of these molecules is thought to occur during wakefulness.

“Jeff (Iliff) also has ideas about how this might be operating in the brain, revolving around this idea that sleep-related or quality sleep-related clearance of these molecules is important during midlife, prior to any signs of cognitive impairment,” Gerstner said. “We think these things happen way early, so it’s important to get quality sleep even in midlife – in your 30s and 40s.”

Gerstner said the study also bolsters that optimal sleep should be on everyone’s list of healthy habits, with diet and exercise.

“Sleep is one of the things that we traditionally would dismiss, but we can’t think like that,” Gerstner said. “We really have to put sleep at a forefront for living a healthy life.”

But getting consistent sleep can be hampered by health problems, breathing disorders, work, a crying baby, caregiver duties or even a cold, Van Dongen added.

We have less control over sleep as we age, he said. Seniors tend to be more sensitive to noises and room temperature.

With aging, an internal biological clock that supports sleep-wake cycles becomes less robust, Van Dongen said.

“We know that people with mild cognitive impairment and who ultimately end up with Alzheimer’s disease also have a disrupted biological clock; we can see it actually stops working properly,” Van Dongen said. “If your biological clock isn’t keeping your rhythms properly in sync, then it makes it even harder to get that sleep and get it on a regular basis.”

He still questions what might come first, if sleep becomes irregular and then brain health deteriorates, or health deteriorates with aging so that people don’t sleep well and have consequences.

“It’s probably a little bit of both.”

Van Dongen tells sleep-deprived people to take naps and catch up on weekends, but the study casts some doubt.

If pressed, Van Dongen said he’d still suggest grabbing sleep when and where possible, “because getting the sleep is more important, I think, than not getting the sleep.”

He offers tips to better the sleep odds:

Consider the season

Winter and its accompanying darkness affect sleep regularity. “The same biological clock involved in the sleep-wake cycle is affected by the bright of light in daytime and pitch darkness in the night, but that darkness lengthens this time of year.”

During daytime, go outdoors to boost the biological clock, even if the sky is overcast. As you wind down for bed, lower inside lighting.

Adjust to earlier bedtimes

By age 50, the internal biological clock for most people begins a return to its former childhood self, Van Dongen said. Aging makes it harder to stay up late and easier to rise early. Adjust to that to get more sleep. “That’s an easy thing to try.”

Protect health

Otherwise, pain and health conditions can disrupt sleep. If sleep issues persist, talk to a doctor about Spokane clinics that treat sleep disorders.

Limit alcohol

A nightcap can aid sleep, Van Dongen said, but also creates additional waste in the body and brain that can wake you up in the middle of the night. Drinking more doesn’t help.

Turn off electronics and cellphone

Instead, wind down an hour before bed. Blue light over-stimulates the biological clock.

Minimize worry and stress

Van Dongen said this tip is more his opinion. “The holidays are a good time,” he said. “We also need to celebrate and have joy in life.”

If people can’t maintain regular slumber, it can lead to worry that affects sleep.

“Don’t beat yourself up, because that can make your sleep worse.”