Over the past decade or two, scientists and clinicians alike have woken up to the importance of sleep, for both cognitive and physical health. Besides the day-to-day problems caused by lack of sleep (fatigue, lack of focus, crankiness — we’ve all been there), interrupted sleep has been increasingly linked to heart disease, stroke and Alzheimer’s disease.
Certain factors in Maine make the struggle for sleep in the Pine Tree State unique. Clifford Singer, chief of Geriatric Mental Health and Neuropsychiatry at Northern Light Acadia Hospital, has been studying sleep for more than 30 years. He said two factors stand above the rest when it comes to understanding sleep in Maine: the aging population and the sunlight, or lack thereof.
The extreme changes in daily sunlight between Maine’s winter and summer months can not only exacerbate season depression — which itself can affect sleep — but, depending on the person, it can also muddle the body’s natural rhythms.
“We each have different tendencies in our normal circadian rhythm and flexibility to adjust,” Singer said. “The problem in Maine is that your body clock may tend to get desynchronized because it’s not getting light exposure early enough in the morning, so your sleep time can drift later and later, and your wake up time can drift later and later.”
Aging also impacts the quality of sleep. Singer said that as we age, sleep becomes more fragmented, with more nighttime awakenings and resulting daytime sleepiness. The cognitive decline that comes naturally with aging often exacerbates sleep issues. Plus, older people are less likely to socialize and be active — both important to sustained cognitive health — in the winter, especially in rural areas.
With the stakes for mental and physical health, doctors and researchers alike are working to better understand what keeps us from sleeping, how it impacts our health and what can be done to bring Mr. Sandman to more Mainers.
How a snore turns to more
Take sleep apnea, a common disorder affecting nearly 22 million Americans where interruptions in breathing while during sleep cause regular, sometimes undetected, arousals. Even a slight gag in a rolling snore is enough to impair attention, focus and retention throughout the day, even if the disturbances go unnoticed.
“Sleep apnea is [a] source of problems with thinking and memory,” Singer said. “When your airways close and you’re struggling to breathe, that triggers a microarousal and that can happen hundreds of times during the night.”
Sleep clinicians have also seen that sleep apnea is more common in aging populations.
“We have the oldest state in the country,” said Robert Weiss, a pulmonologist and sleep disorders specialist at Mount Desert Island Hospital, “[and] sleep apnea is more common in the elderly.”
Weiss, who has been practicing sleep medicine for more than two decades, said that the number of referrals for the disorder have increased over the last decade. He said at the beginning of his career in Maine, he saw sleep apnea cases that fell in the classic paradigm — specifically, overweight, middle-aged men. Now, that’s changing.
“In the last 10 or so years, we’re seeing more or more people we wouldn’t have thought of as having sleep apnea,” Weiss said. “We’re more aware of [sleep apnea], but we’re also getting older, we’re getting heavier [and] we have all these electronic things that are interrupting our sleep.”
Stephen Gorman, medical director of the Maine General Sleep Disorders Clinic, has also observed an increase in the number and variety of sleep disorder patients in Maine over his 13 years practicing sleep medicine in the state.
“The complexity of patients has increased,” Gorman said. “Many patients with sleep apnea have other medical conditions, and sleep apnea has been increasingly linked to cardiac problems.”
The connection between sleep and Alzheimer’s disease
Increasingly, studies suggest that lack of sleep precedes — and may contribute to — the on-set of Alzheimer’s disease. Researchers in Maine have started delving into this connection.
“A reasonably large percentage of patients with Alzheimer’s disease also experience sleep disruption,” said Kristen O’Connell, principal investigator at the O’Connell Lab at The Jackson Laboratory. “In many of those patients, sleep disruption precedes memory loss, but the methods that underlie it are not well understood.”
The prevailing theory is that during sleep, the production of an amino acid called beta amyloid shuts down and the protein is cleared from the brain. The build-up of beta amyloid “plaques” that haven’t been cleared away is the first step in the development of Alzheimer’s disease. Scientists are not yet sure how causal this connection is, though, given other factors, like diet, exercise and genetic makeup.
To try to determine how central a role sleep plays in the on-set of the neurodegenerative disease, O’Connell and her colleagues at Jackson Lab genetically engineered lab mice with the same genetic markers present in humans with Alzheimer’s disease. O’Connell said that the genetically engineered mice present similar symptoms as human Alzheimer’s patients, including neurodegeneration, synapse loss and cognitive impairment.
The scientists study the mice — ones with the genetic markers, and control populations without that show what normal mouse aging should look like — over their lifetimes in different conditions.
“In our studies, we are able to manipulate the light cycle, but we can also control exercise and socialization,” said Catherine Kaczorowski, principal investigator at Jackson Lab. “You can start to disentangle which of those things matter more for cognitive disabilities and dementia.”
The mice sleep in cages with sensors built into the floor to track the subjects’ breathing and movement during sleep to determine the quality and quantity of their sleep.
“What we’re able to do is get at the mechanisms of sleep apnea disruptions in humans and ask is it casually related,” Kaczorowski said. “Whether sleep apnea is exacerbating the symptoms is very different from knowing whether it’s causing dementia.”
Bringing sleep studies to the bedroom
Though the mice at Jackson Lab are considered, according to Kaczorowski, the “most translationally relevant mouse models for Alzheimer’s disease,” the fact remains that studies like these are limited, for now, in that they cannot be conducted on humans.
Even for physicians, studying and treating sleep can be difficult. Conducting a sleep study on a human in a lab is invasive. They require patients to stay at least overnight in unfamiliar locations hooked up to various leads on their heart, chest, legs and other parts of their bodies. Add that to the fact that much of the state’s aging population lives in rural areas.
“It is somewhat more difficult and challenging to study sleep in a rural area,” Weiss said. “Typically, sleep centers are in cities, so access in rural Maine is challenging.”
Increasingly, though, with advancing technology sleep studies can be conducted at home. Weiss described one home sleep test that is basically a sensor in a box that is strapped to the patient’s chest to monitor breathing along with a pulse oximeter clipped to the finger to track oxygen levels.
“For testing for sleep apnea, it is preferred, and insurance will only pay for a home sleep study,” Weiss said. “A very sick person or someone who has complex sleep disorders may have to come in [to the lab].”
Home sleep studies do not provide the same array of data that lab tests do, but even diagnosing sleep apnea could bring patients one step closer to improving brain health.
“Those home tests have become increasingly available in the last five to 10 years,” Gorman said. “That has helped with access.”
Maine researchers are looking to take the in-home sleep test to the next level, especially with respect to detecting cognitive disorders. Activas Technology, a company founded by professors of electrical engineering, biomedical science and psychology at the University of Maine, has developed a mattress pad designed to pick up tiny movements in the bed that could potentially be linked to developing cognitive disorders — not unlike the mice in the sensor-laden cages.
“We make decisions using an artificial intelligence software that we developed in our laboratory by looking at the characteristics of people with mild cognitive impairment and what their sleep looks like [when it comes to] autonomic variables like tiny movements of your hands and respirations,” said Marie Hayes, CEO and co-founder of Activas Diagnostics and professor of psychology at the University of Maine.
Hayes said that the non-invasive technique will not only open access for doctors to diagnose patients, but it will also help yield more accurate results.
“To do a really good sleep study is really quite invasive,” Hayes said. “You do that to a person with mild cognitive impairment, that is not going to be OK. Very small disruptions are very big disruptions to them. We are excited to offer this product because it addresses the concern and discomfort.”
The future of sleep in Maine
As technology continues to advance, doctors and researchers see potential for continuing to improve the availability of sleep data.
“There are a number of consumer gadgets that have not been completely validated as medical devices, but there’s probably a role in the future for more of the consumer wearable devices to monitor sleep and aid in the diagnosis of sleep disorders and treatment,” Gorman said.
Though Singer works closely with researchers across the state, he is generally skeptical about the quality of data gained from human subjects using simple tests when it comes to drawing broad conclusions about sleep and the brain.
“If you’re going to draw conclusions about certain brain disorders, you need to know exactly who you’re studying,” Singer said. “We want to make sure [the] cognitive problems aren’t due to Parkinson’s or stroke or depression or medications or any one of dozens of medical and neurologic and psychiatric disorders. There’s too much heterogeneity in that system, too much noise, too many other things impacting sleep and cognition.”
Still, Singer said, “It’s good to have a skeptic among people doing the research,” and he still believes that Maine is headed in a positive direction.
“There’s increasing awareness and sophistication about sleep, so people have a better understanding of its importance,” Singer said. “There’s still a little bit of a badge of honor of people bragging about how little sleep they get and how little sleep they need [but] I think we’re getting past that. People are prioritizing sleep more. It’s an important public health issue.”