Sleep

  • Sleep, Sleep Health

    Sleep Chaos Fuels Type 2 Diabetes Risk

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    Original Article | Sleep Review Magazine

    Middle-aged to older adults with inconsistent sleep duration had a heightened risk of developing diabetes compared to those with more consistent sleep patterns.

    Summary: A study conducted by Brigham and Women’s Hospital found that middle-aged to older adults with inconsistent sleep durations had a significantly higher risk of developing type 2 diabetes compared to those with more consistent sleep patterns. The research, analyzing data from over 84,000 participants, revealed that irregular sleep patterns increased diabetes risk by 34%. Researchers say the study underscores the importance of maintaining regular sleep patterns as a modifiable lifestyle factor to prevent type 2 diabetes.

    Woman with Diabetes

    Key Takeaways:

    • Increased Diabetes Risk with Irregular Sleep: The study found that individuals with the most irregular sleep patterns had a 34% higher risk of developing type 2 diabetes compared to those with consistent sleep durations.
    • Importance of Regular Sleep for Diabetes Prevention: Researchers highlighted the importance of regular sleep patterns as a modifiable lifestyle factor that can help reduce the risk of type 2 diabetes. The findings suggest that promoting consistent sleep could be a key strategy in diabetes prevention efforts.
    • Need for Diverse and Long-term Studies: The study had limitations, including a predominantly older, white, and healthy participant group, and short-term sleep data collection. Future research aims to include younger and more diverse populations to better understand the biological mechanisms and confirm these findings across different demographics.

    Getting consistent sleep could help stave off type 2 diabetes, new research suggests. 

    A study led by investigators at Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system, analyzed sleep patterns over seven nights and then followed participants for more than seven years. 

    The researchers discovered that irregular sleep durations were associated with an increased risk of diabetes, with individuals with the greatest irregular patterns having a 34% higher diabetes risk than their counterparts. 

    Importance of Regular Sleep Patterns

    Researchers say the findings, published in Diabetes Care, suggest the importance of regular sleep for diabetes prevention.

    “Our study identified a modifiable lifestyle factor that can help lower the risk of developing type 2 diabetes,” says lead author Sina Kianersi, PhD, a research fellow in the Channing Division of Network Medicine at Brigham and Women’s Hospital, in a release. “Our findings underscore the importance of consistent sleep patterns as a strategy to reduce type 2 diabetes.”

    Type 2 diabetes affects close to half a billion people worldwide and is one of the top 10 leading causes of death and disability. The number of people with type 2 diabetes is expected to more than double to 1.3 billion by 2050. Researchers say this situation highlights the need for innovative strategies for diabetes prevention.

    Study Details and Findings

    The new study analyzed accelerometry data from more than 84,000 participants in the UK Biobank Study to investigate any possible association between sleep and type 2 diabetes. 

    Participants were an average age of 62 years (57% female, 97% white) and were initially free of diabetes. They wore accelerometers—devices like watches that monitor movement—for seven nights. The participants were followed for approximately 7.5 years, tracking diabetes development mostly through medical records.

    The study set out to investigate two key questions: First, whether irregular sleep durations may promote diabetes development through circadian disruption and sleep disturbance and, second, whether this association varies across genetic predispositions to diabetes.

    Risk Factors and Analysis

    The investigators found that more irregular sleep duration was associated with higher diabetes risk after adjusting for a wide range of risk factors. This association was more pronounced in individuals with longer sleep duration and lower polygenic risk score for diabetes.

    The data revealed that compared to participants with regular sleep patterns, those with irregular sleep (where day-to-day sleep duration varied by more than 60 minutes on average) had a 34% higher risk of developing diabetes. The risk decreased, yet persisted, even after accounting for lifestyle, co-morbidities, family history of diabetes, and obesity indicators.

    There were some study limitations. Certain lifestyle information used in the research was collected up to five years before the accelerometer study began. This might have affected the accuracy of the results. Also, the assessment of sleep duration based on seven days may not capture long-term sleep patterns. Lastly, study participants were mainly healthy, older, and white, and may not represent outcomes for more diverse populations.

    Future Research Directions

    The researchers plan to study participants from younger age groups and with diverse racial backgrounds. They are also interested in exploring the biological reasons why sleep irregularity increases the risk of diabetes.

    “Our findings have the potential to improve diabetes prevention on multiple levels,” says Kianersi in a release. “Clinically, they might inform better patient care and treatment plans. Public health guidelines could promote regular sleep patterns. However, more research is needed to fully understand the mechanism and confirm the results in other populations.”

    Photo 91507451 © Piotr Adamowicz | Dreamstime.com

  • Sleep, Sleep Apnea, Sleep Study

    Why the First Half of Your Sleep is Crucial for Brain Reset

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    Original Article | Sleep Review Magazine

    Recent findings reveal that the initial hours of sleep play a crucial role in weakening neuron connections, paving the way for new learning the following day.

    Summary: A study by University College London, published in Nature, shows that during the first half of sleep, the brain reduces connections made between neurons while awake, supporting the Synaptic Homeostasis Hypothesis. This “reset” prepares the brain for new learning. Using zebrafish with optically translucent genes for easy imaging of synapses, researchers found that sleep helps manage the strength of neuron connections based on prior wakefulness. The study raises questions about the second half of sleep, suggesting it might serve other brain functions like waste clearance or cell repair.

    Key Takeaways: 

    • The first half of sleep is crucial for weakening the connections between neurons that are formed during wakefulness, helping to reset the brain for new learning the next day.
    • The study utilized optically translucent zebrafish, allowing researchers to visually track how synapses in the brain were altered during different sleep-wake cycles.
    • While the first half of sleep focuses on synaptic weakening, the function of the second half remains less understood, with theories suggesting it may involve brain waste clearance or cell repair.

    During sleep, the brain weakens the new connections between neurons that had been forged while awake—but only during the first half of a night’s sleep, according to a new study in fish by University College London scientists.

    The researchers say their findings, published in Nature, provide insight into the role of sleep but still leave an open question about what function the latter half of a night’s sleep serves. The researchers say the study supports the Synaptic Homeostasis Hypothesis, a key theory on the purpose of sleep which proposes that sleeping acts as a reset for the brain.

    “When we are awake, the connections between brain cells get stronger and more complex. If this activity were to continue unabated, it would be energetically unsustainable. Too many active connections between brain cells could prevent new connections from being made the following day,” says lead author professor Jason Rihel, PhD, in a release. “While the function of sleep remains mysterious, it may be serving as an ‘offline’ period when those connections can be weakened across the brain, in preparation for us to learn new things the following day.”

    Study Shows Sleep’s Impact on Brain

    For the study, the scientists used optically translucent zebrafish, with genes enabling synapses to be easily imaged. The research team monitored the fish over several sleep-wake cycles.

    The researchers found that brain cells gain more connections during waking hours and then lose them during sleep. They found that this was dependent on how much sleep pressure (need for sleep) the animal had built up before being allowed to rest; if the scientists deprived the fish from sleeping for a few extra hours, the connections continued to increase until the animal was able to sleep.

    “If the patterns we observed hold true in humans, our findings suggest that this remodeling of synapses might be less effective during a mid-day nap when sleep pressure is still low, rather than at night when we really need the sleep,” says Rihel in a release. 

    Neural Rearrangement Peaks in Early Sleep

    The researchers also found that these rearrangements of connections between neurons mostly happened in the first half of the animal’s nightly sleep. This mirrors the pattern of slow-wave activity, which is part of the sleep cycle that is strongest at the beginning of the night.

    “Our findings add weight to the theory that sleep serves to dampen connections within the brain, preparing for more learning and new connections again the next day,” says first author Anya Suppermpool, PhD, in a release. “But our study doesn’t tell us anything about what happens in the second half of the night. There are other theories around sleep being a time for clearance of waste in the brain, or repair for damaged cells—perhaps other functions kick in for the second half of the night.”

    Photo 97439374 © Siriporn Kaenseeya | Dreamstime.com

  • Sleep, Sleep Study

    Light at Night Tied to Diabetes Risk in Largest Study to Date

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    Original Article Medscape | Christina Szalinski

    Concerned about your patient’s type 2 diabetes risk? Along with the usual preventive strategies — like diet and exercise and, when appropriate, glucagon-like peptide 1 (GLP-1) agonists — there’s another simple, no-risk strategy that just might help: Turning off the light at night.

    A study in The Lancet found that people who were exposed to the most light between 12:30 AM and 6 AM were 1.5 times more likely to develop diabetes than those who remained in darkness during that timeframe.

    The study builds on growing evidence linking nighttime light exposure to type 2 diabetes risk. But unlike previous large studies that relied on satellite data of outdoor light levels (an indirect measure of light exposure), the recent study looked at personal light exposure — that is, light measured directly on individuals — as recorded by a wrist-worn sensor.

    “Those previous studies likely underestimated the effect,” said study author Andrew Phillips, PhD, professor of sleep health at Flinders University in Adelaide, Australia, “since they did not capture indoor light environments.”

    Using data from 85,000 participants from the UK Biobank, the recent study is the largest to date linking diabetes risk to personal light exposure at night.

    “This is really a phenomenal study,” said Courtney Peterson, PhD, a scientist at the University of Alabama at Birmingham’s Diabetes Research Center, who was not involved in the study. “This is the first large-scale study we have looking at people’s light exposure patterns and linking it to their long-term health.”

    What the Study Showed

    The participants wore the light sensors for a week, recording day and night light from all sources — whether from sunlight, lamps, streetlights, or digital screens. The researchers then tracked participants for 8 years.

    “About half of the people that we looked at had very dim levels of light at night, so less than one lux — that basically means less than candlelight,” said Phillips. “They were the people who were protected against type 2 diabetes.”

    Those exposed to more light at night — defined in the study as 12:30 AM-6 AM — had a higher risk for type 2 diabetes. The risk went up as a dose response, Phillips said: The brighter the light exposure, the higher the diabetes risk.

    Participants in the top 10% of light exposure — who were exposed to about 48 lux , or the equivalent of relatively dim overhead lighting — were 1.5 times more likely to develop diabetes than those in the dark. That’s about the risk increase you’d get from having a family history of type 2 diabetes, the researchers said.

    Even when they controlled for factors like socioeconomic status, smoking, diet, exercise, and shift work, “we still found there was this very strong relationship between light exposure and risk of type 2 diabetes,” said Phillips.

    How Light at Night May Increase Diabetes Risk

    The results are not entirely surprising, said endocrinologist Susanne Miedlich, MD, a professor at the University of Rochester Medical Center, Rochester, New York, who was not involved in the study.

    Light at night can disrupt the circadian rhythm, or your body’s internal 24-hour cycle. And scientists have long known that circadian rhythm is important for all kinds of biologic processes, including how the body manages blood sugar.

    One’s internal clock regulates food intake, sugar absorption, and the release of insulin. Dysregulation in the circadian rhythm is associated with insulin resistance, a precursor to type 2 diabetes.

    Phillips speculated that the sleep hormone melatonin also plays a role.

    “Melatonin does a lot of things, but one of the things that it does is it manages our glucose and our insulin responses,” Phillips said. “So if you’re chronically getting light exposure at night, that’s reducing a level of melatonin that, in the long term, could lead to poor metabolic outcomes.”

    Previous studies have explored melatonin supplementation to help manage diabetes. “However, while melatonin clearly regulates circadian rhythms, its utility as a drug to prevent diabetes has not really panned out thus far,” Miedlich said.

    Takeaways

    Interventional studies are needed to confirm whether strategies like powering down screens, turning off lights, or using blackout curtains could reduce diabetes risk.

    That said, “there’s no reason not to tell people to get healthy light exposure patterns and sleep, especially in the context of diabetes,” said Phillips.

    Other known strategies for reducing diabetes risk include intensive lifestyle programs, which reduce risk by up to 58%, and GLP-1 agonists.

    “Probably a GLP-1 agonist is going to be more effective,” Peterson said. “But this is still a fairly large effect without having to go through the expense of buying a GLP-1 or losing a lot of weight or making a big lifestyle change.”

  • Sleep, Sleep Health

    Why sleep soothes distress: Neurobiology explained

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    Original Post | Caroline Pierce, Medical Express

    A study published in Nature Reviews Neuroscience by an international team including the Woolcock’s Dr. Rick Wassing examined research into sleep disorders over more than two decades to prove a good night’s sleep is the perfect remedy for emotional distress.

    Nothing we haven’t known forever, some would argue, but Dr. Wassing who has spent the past two years on the project says there’s much more to it than that.

    “What we have done with this study is explain why. We looked at studies in neurobiology, neurochemistry and clinical psychology to get a real understanding of the mechanisms underlying how sleep helps us to deal with our emotional memories.”

    What the team of researchers believe after aggregating more than 20 years’ of scientific knowledge is that the way certain neurochemicals (for example, serotonin and noradrenaline) are regulated during sleep is crucial for the processing of emotional memories and our long-term mental health.

    Chemistry and circuitry

    Serotonin is involved in many, if not almost all, aspects of learning emotional experiences. It helps us assess and understand the world around us. Noradrenaline is all about “fight or flight”—it allows us to assess and respond to danger. Both are turned off during rapid eye movement (REM) sleep and that creates this “really beautiful opportunity for the brain to engage in processes that are otherwise not doable when we are awake,” explains Dr. Wassing.

    There are two main ways we process emotional memory during sleep, he says, and they involve the brain’s hippocampus and amygdala.

    Our brains store what we learn each day. This learning is governed by the hippocampus aggregating and cataloging this new information into the “novelty” memory store as we process it. At the same time, if that new experience is emotional, the amygdala is very active and coupled with the autonomic nervous system—think racing heart, knots in your stomach, skin crawling.

    During REM sleep, our brains reactivate these new memories. It is as if the brain replays a summary of what had happened when we experienced the memory. But during REM sleep, when the noradrenergic and serotonergic systems are turned off, these memories can be moved into the “familiar” storage without experiencing the physical “fight or flight” response. That can’t happen while we’re awake or—as is the case for people with sleep disorders—when we don’t get consistent blocks of REM sleep.

    Shining a light on the brain

    Much of what we now know about the way information is processed by the brain comes from the relatively new field of optogenetics which is used to activate or inhibit very specific cell types in a neuronal network. This has allowed researchers to see what cell types and brain regions are involved in encoding emotional memories.

    According to Dr. Wassing, it has meant real breakthroughs in terms of our understanding of brain circuitry and neurobiology.

    It’s all well and good, he says, to look at neurons and receptors and circuits, but the researchers also assessed clinical psychology studies and found that their findings, especially relating to disconnecting amygdala reactivity and shutting down the autonomic nervous system, were corroborated.

    “All three levels of neuroscience align to produce the same conclusion, that the way the brain functions during REM sleep is important for processing emotional memories.”

    Making ‘good sleepers’

    So, where to now? “We know that with insomnia or other sleep disorders where people wake up from sleep a lot, we see an increased risk of developing mental health problems. Our hypothesis would be that that these awakenings from sleep lead to the fact that the noradrenergic system is not shut down for long periods of time (in fact, they might actually show enhanced activity) and that’s why these people might not be able to regulate emotional memories.”

    “The solution is to try to get a good night’s sleep, yes, but the problem is how then do we do that? We know that two out of three people with insomnia benefit from cognitive behavioral therapy for insomnia (CBTI) but that is mostly based on subjective ratings. There’s less evidence on objective sleep measures. The insomnia patient after CBTI is not necessarily a good sleeping individual, they still have some sleep disturbances but CBTI is enabling them to better deal with them.”

    “We need to critically think more about the mechanisms that regulate sleep. It’s very hard to target one system because sleep is very dynamic—the noradrenergic system shuts down during REM sleep, but it actually needs to be active during non-REM sleep so you can’t just turn it off for the entire sleep cycle.”

    “We need really creative ideas about how to design an intervention or a drug that can target these dynamics that happen during sleep and enable those systems to renormalize. We need to be targeting objective sleep and making people with insomnia good sleepers again.”