Sleep Health

  • Sleep Chaos Fuels Type 2 Diabetes Risk

    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

  • Why sleep soothes distress: Neurobiology explained

    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.”

  • Study reveals sleep effects how young you feel

    By Eric Ralls Earth.com staff writer

    Have you ever noticed how a well-maintained classic car can turn heads and exude a timeless charm? Its age has become subjective. Just like a vintage automobile that has been meticulously cared for, feeling young is not merely a superficial notion — it is intrinsically connected to tangible health benefits.

    Subjective age, the internal gauge that measures how old we perceive ourselves to be, transcends the realm of simple self-perception.

    Much like how a classic car’s performance and longevity are tied to its upkeep, research has revealed that individuals who feel younger than their chronological age tend to enjoy longer lifespans, superior mental and physical well-being, and a host of positive psychological attributes.

    These findings have led experts to propose the integration of subjective age as a biophysical indicator of aging, serving as a vital component of comprehensive health assessments.

    Young and Youthful Woman

    Sleep-age connection

    Researchers at Stockholm University have discovered that sleep affects how old you feel. The study, published in the scientific journal Proceedings of the Royal Society B, reveals that feeling sleepy can make you feel ten years older.

    Leonie Balter, a researcher at the Department of Psychology, Stockholm University, explains, “Given that sleep is essential for brain function and overall well-being, we decided to test whether sleep holds any secrets to preserving a youthful sense of age.”

    Power of a good night’s sleep

    In the first study, 429 individuals aged 18 to 70 were asked how old they felt, how many days in the past month they had not gotten enough sleep, and how sleepy they were.

    The results showed that for each night with insufficient sleep in the past month, participants felt on average 0.23 years older.

    To further investigate the causal relationship between sleep and subjective age, the researchers conducted a second study involving 186 participants aged 18 to 46.

    Participants restricted their sleep for two nights, with only four hours in bed each night, and another time slept sufficiently for two nights, with nine hours in bed each night.

    The findings were striking. After sleep restriction, participants felt on average 4.4 years older compared to when having enjoyed sufficient sleep.

    Staying young at heart by safeguarding your sleep

    The effects of sleep on subjective age appeared to be related to how sleepy they felt. Feeling extremely alert was related to feeling 4 years younger than one’s actual age, while extreme sleepiness was related to feeling 6 years older than one’s actual age.

    “This means that going from feeling alert to sleepy added a striking 10 years to how old one felt,” says Leonie Balter.

    Previous studies have shown that feeling younger than one’s actual age is associated with longer, healthier lives. There is even support for subjective age to predict actual brain age, with those feeling younger having younger brains.

    The implications of this study are clear. “Safeguarding our sleep is crucial for maintaining a youthful feeling. This, in turn, may promote a more active lifestyle and encourage behaviours that promote health, as both feeling young and alert are important for our motivation to be active,” states Leonie Balter.

    Unlocking the secrets of age by sleeping

    In a world where we are constantly searching for the fountain of youth, it turns out that the secret to feeling young again might be as simple as getting a good night’s sleep.

    By prioritizing our sleep and ensuring that we get enough rest each night, we can not only feel more alert and energized but also maintain a youthful sense of age.

    So, the next time you find yourself longing for the vitality of your younger years, remember that the key to unlocking that feeling might just be a few extra hours of shut-eye.

    More about subjective age

    As discussed above, subjective age refers to how old an individual feels, regardless of their chronological age. It is a personal perception that can be influenced by various factors, such as physical health, mental well-being, and life experiences.

    People often report feeling younger or older than their actual age, and this subjective age can have significant implications for their overall health and quality of life.

    Benefits of feeling younger

    Numerous studies have shown that feeling younger than one’s chronological age is associated with a range of positive outcomes.

    Individuals who feel younger tend to have better physical and mental health, higher levels of life satisfaction, and a more positive outlook on life.

    They are also more likely to engage in healthy behaviors, such as regular exercise and maintaining a balanced diet.

    Impact of subjective age on longevity

    Research suggests that subjective age may even predict longevity. A study published in the Journal of the American Medical Association found that individuals who felt younger than their actual age had a lower risk of mortality compared to those who felt older.

    This finding highlights the potential importance of subjective age as a biophysical marker of aging and its relevance in health assessments.

    Factors influencing subjective age

    Several factors can influence an individual’s subjective age, including:

    • Physical health: Chronic illnesses, disabilities, and poor physical functioning can make people feel older than their chronological age.
    • Mental health: Depression, anxiety, and stress can contribute to feeling older, while positive emotions and a sense of purpose can help individuals feel younger.
    • Social connections: Strong social support and engaging in meaningful relationships can promote a youthful sense of age.
    • Life experiences: Major life events, such as retirement, the loss of a loved one, or becoming a grandparent, can impact how old an individual feels.

    Harnessing the power of subjective aging

    In summary, subjective age is a fascinating concept that has garnered increasing attention from researchers and healthcare professionals alike.

    By understanding the factors that influence subjective age and its potential implications for health and well-being, we can develop strategies to promote a more youthful mindset and improve overall quality of life.

    Encouragingly, recent research on the link between sleep and subjective age suggests that we may have more control over how old we feel than previously thought.

    The full study was published in the journal Proceedings of the Royal Society B Biological Sciences.

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  • Best CPAP Alternatives

    If you have sleep apnea, here’s what to know about dental devices, tongue trainers, mouth tape, and more.

    Consumer Reports | By Kevin Loria

    When you have obstructive sleep apnea, or OSA addressing it is key. Left untreated, OSA is linked to daytime sleepiness and an increased risk of anxiety, diabetes, hypertension, and stroke.

    With OSA, your breathing pauses during sleep because something blocks your airway, like your tongue or relaxed throat muscles, explains Richard Schwab, MD, chief of the division of sleep medicine at the University of Pennsylvania Perelman School of Medicine in Philadelphia. Losing weight, quitting smoking, and limiting alcohol can all help ease obstructive sleep apnea symptoms such as snoring, says Ana Krieger, MD, medical director of the Center for Sleep Medicine at Weill Cornell Medicine in New York City.

    CPAP Machine

    Sleep apnea’s severity is determined by something called your apnea-hypopnea index (AHI): the number of times per hour you fully or partially stop breathing for 10 seconds or longer. The primary treatment for people with moderate (15 to 29 AHI) or severe (30 AHI and higher) obstructive sleep apnea is a continuous positive airway pressure (CPAP) machine, which keeps your airway open by pumping air through a mask you wear over your mouth and/or nose when you sleep.

    Many people have difficulty tolerating CPAP and don’t stick with it, however. The good news is that CPAP machines have become smaller and quieter, with more comfortable options available. And for some people with mild (5 to 14 AHI) or even moderate OSA, less invasive alternatives to CPAP may be worth considering.

    A Common CPAP Alternative

    A dental device designed to move the jaw so that the tongue shifts toward the front of the mouth can help keep the airway open. It’s one of the primary alternatives to CPAP, Schwab says, and can also be used with CPAP to help make severe obstructive sleep apnea milder.

    A dentist who specializes in sleep medicine (find one at dentalsleep.org) will be able to customize its fit to help your breathing without causing harm to your bite or teeth, says Kevin Postol, DDS, president-elect of the American Academy of Dental Sleep Medicine. These custom-made oral appliances can cost between $2,000 and $4,000, according to Schwab, but may be covered by insurance.

    There are much cheaper options available online to treat snoring, but experts say these may not help with OSA, and could move teeth out of place or cause jaw issues if they’re not properly fitted.

    Other Sleep Apnea Treatments

    • Position therapy: For some, sleeping on the back can make obstructive sleep apnea dramatically worse. In these cases, switching to side sleeping—perhaps using pillows or a tennis ball attached to a shirt back—can sometimes get AHI into the mild range.
    • Tongue trainer: In 2021, the Food and Drug Administration approved a tongue-stimulating device for mild sleep apnea called eXciteOSA, which people wear for 20 minutes a day for six weeks and then 20 minutes a couple of times a week indefinitely. It costs $1,650 and is not covered by insurance. More research is still needed on its efficacy, Krieger says.
    • Mouth tape: While it’s a popular suggestion that may reduce snoring, taping the mouth shut is not an effective or safe option for people with obstructive sleep apnea, Schwab says.
    • Surgery: Some people who can’t tolerate CPAP have upper airway surgery to reduce the size of their soft palate or other tissue in their throat. But such options don’t always work, have serious potential complications, and cannot be reversed. So in general, they should not be first-line treatments, Schwab says. A newer option is a surgically implanted device called Inspire. Approved in 2014, it stimulates a nerve that moves your tongue to keep your airway open. Inspire can be removed if it is not tolerated, but it should also be tried only if someone is unable to use CPAP, and it is not an option for everyone.

    Could Weight Loss Meds Treat OSA?

    Because sleep apnea is an anatomic disorder, drugs typically have not been effective, Schwab says. But GLP-1 weight loss medications such as Wegovy may be used in the future, perhaps in concert with an oral appliance or airway surgery.

    That’s on the table because obesity is a primary risk factor for OSA: One 2022 study found that for every 7-pound drop in weight, there’s a roughly 7 percent drop in AHI. But more research on using these meds for obstructive sleep apnea is needed.

    Editor’s Note: This article also appeared in the April 2024 issue of Consumer Reports On Health.

  • How quality sleep can reduce the risk of heart disease and stroke

    Original Article | Medical News Today

    • Researchers report that better sleep may translate into a lower risk of cardiovascular disease.
    • They add that consistent and healthy sleep patterns can improve a person’s overall well-being.
    • Experts say people having trouble sleeping should rethink pre-sleep activities and avoid stimulation before bedtime.

    studyTrusted Source published in the journal JAMA Network Open reports that midlife and older adults with healthy sleep habits have a better chance of avoiding cardiovascular disease.

    Researchers used data collected between 2008 and 2018 from the Dongfeng-Tongji cohortTrusted Source, an ongoing, prospective study in Shiyan, China.

    The research team looked at 15,306 individuals with an average age of 66 years with 58% being female and 42% being male. The researchers reported that 5,474 (36%) people had persistent unfavorable sleep patterns and 3,946 (26%) had persistent favorable sleep patterns.

    The researchers established that 3,669 members of the study group had documented cases of cardiovascular disease during that period, including 2,986 cases of coronary heart disease and 683 cases of stroke over a mean follow-up period of nearly 5 years.

    Compared to people with persistent unfavorable sleep patterns, those with persistent favorable sleep patterns had a significantly lower risk of new onset cardiovascular disease, coronary heart disease, and stroke during the follow-up period.

    Researchers said the genetic risk for cardiovascular disease didn’t modify these associations.

    “However, sleep pattern changes and genetic risk were jointly associated with the [coronary heart disease] and stroke risk in a dose-dependent manner,” the study authors wrote.

    Healthy sleep and heart disease risk 

    The five-year patterns in the study were determined by bedtime, sleep duration, sleep quality, and midday napping as well as polygenic risk scores for coronary heart disease and stroke.

    The participants included people with complete sleep information at the baseline survey from 2008 to 2010 and the first follow-up survey in 2013. Subjects with no history of cardiovascular disease or cancer were prospectively assessed from 2013 to 2018. Scientists performed their statistical analysis in November 2023.

    The authors pointed out cardiovascular disease “is a major cause of morbidity and mortality worldwide. In 2019, cardiovascular deaths accounted for approximately one-third of all deaths globally, including more than 40% of deaths in China.

    The researchers also said that as the cardiovascular disease burden keeps rising in nearly every country, research identifying modifiable risk factors for prevention of serious heart disease is urgent.

    The team acknowledged previous studies have shown an association of sleep with cardiovascular health.

    However, the researchers said most of those studies used only a single measurement, which might not adequately reflect the association of overall sleep with cardiovascular disease as sleep habits may change over time.

    Researchers cited one studyTrusted Source of 9,309 participants living in Europe that indicated that maintaining healthy sleep patterns over a 2-year to 5-year period was associated with a lower risk of cardiovascular disease and coronary heart disease but not stroke.

    However, they noted that the research looked at people in midlife who typically adjusted their sleep patterns around work schedules.

    Lifestyle and genetics also factors in heart health 

    The study authors noted that more research on older, retired people with more natural sleep patterns is still necessary.

    The researchers added that lifestyle and genetic factors are also associated with cardiovascular disease, and previous research has shown people with healthy lifestyles had a lower risk of coronary heart disease and stroke, even among those at high genetic risk.

    “To fill the evidence gap, we collected sleep information at two time points approximately five years apart and prospectively explored the long-term outcomes of changes in sleep patterns on the subsequent incidence of [cardiovascular disease] outcomes among middle-aged and older Chinese retirees,” the study authors wrote. “We further investigated how the five-year changes in sleep patterns interact and combine with [cardiovascular disease]-related genetic variants for the risk of [cardiovascular disease] outcome.”

    Chelsey Borson, a sleep expert and founder of baby sleep consulting service Luna Leaps who was not involved in the study, told Medical News Today that sleep has profound impacts on overall health, including heart health.

    “The link between adequate sleep and heart health is increasingly recognized as vital. Sleep serves as a period of recovery and repair for the heart, reducing stress and inflammation, major risk factors for heart disease,” Borson explained. “It’s not an entirely new idea, but the depth of understanding has deepened significantly in recent years as research has advanced.”

    Borson said studies show people getting fewer than seven hours of sleep per night tend to have higher risks of developing cardiovascular issues such as hypertension, coronary artery disease, and myocardial infarction, which “underscores sleep’s role in regulating blood pressure, heart rate, and cardiovascular stability.”

  • How the Brain Decides Which Memories to Keep Permanent During Sleep

    Original Article | Sleep Review Magazine

    A new study proposes a mechanism that determines which memories are tagged as important enough to linger in the brain until sleep makes them permanent.

    Summary: A recent study led by NYU Grossman School of Medicine researchers has identified a mechanism through which the brain selects certain memories to become permanent during sleep. Focusing on the hippocampus’s neurons, the study found that “sharp wave-ripples,” brief bursts of intense neuron activity, play a crucial role in this selection process. Memories followed by these ripples during the day are more likely to be replayed and solidified in sleep.

    Brain in Sleep Mode

    Key takeaways: 

    • The study identified “sharp wave-ripples” in the hippocampus as crucial for selecting which daytime memories become permanent during sleep.
    • Daytime events followed by five to 20 sharp wave-ripples are more likely to be consolidated into long-term memories.
    • This process involves the near-simultaneous firing of 15% of hippocampal neurons, encoding complex information within milliseconds.

    Neuroscientists have established in recent decades the idea that some of each day’s experiences are converted by the brain into permanent memories during sleep the same night. 

    Now, a new study proposes a mechanism that determines which memories are tagged as important enough to linger in the brain until sleep makes them permanent.

    Led by researchers from NYU Grossman School of Medicine, the study revolves around brain cells called neurons that “fire”—or bring about swings in the balance of their positive and negative charges—to transmit electrical signals that encode memories. Large groups of neurons in a brain region called the hippocampus fire together in rhythmic cycles, creating sequences of signals within milliseconds of each other that can encode complex information.

    Called “sharp wave-ripples,” these “shouts” to the rest of the brain represent the near-simultaneous firing of 15% of hippocampal neurons and are named for the shape they take when their activity is captured by electrodes and recorded on a graph. 

    While past studies had linked ripples with memory formation during sleep, the new study, published in Science, found that daytime events followed immediately by five to 20 sharp wave-ripples are replayed more during sleep and so consolidated into permanent memories. Events followed by very few or no sharp wave-ripples failed to form lasting memories.

    “Our study finds that sharp wave-ripples are the physiological mechanism used by the brain to ‘decide’ what to keep and what to discard,” says senior study author György Buzsáki, MD, PhD, the Biggs Professor of Neuroscience in the Department of Neuroscience and Physiology at NYU Langone Health, in a release.

    Walk and Pause

    Illustration 175719502 © Viraldhameliya | Dreamstime.com

    The new study is based on a known pattern: Mammals including humans experience the world for a few moments, then pause, then experience a little more, then pause again. After we pay attention to something, say the study authors, brain computation often switches into an “idle” re-assessment mode. Such momentary pauses occur throughout the day, but the longest idling periods occur during sleep.  

    Buzsaki and colleagues had previously established that no sharp wave-ripples occur as we actively explore sensory information or move, but only during the idle pauses before or after. The current study found that sharp wave-ripples represent the natural tagging mechanism during such pauses after waking experiences, with the tagged neuronal patterns reactivated during post-task sleep.

    Importantly, sharp wave-ripples are known to be made up the firing of hippocampal “place cells” in a specific order that encodes every room we enter and each arm of a maze entered by a mouse. For memories that are remembered, those same cells fire at high speed, as we sleep, “playing back the recorded event thousands times per night.” The process strengthens the connections between the cells involved.

    Tracing Memory Formation

    Photo 30816019 © Noam Kahalany | Dreamstime.com

    For the current study, successive maze runs by study mice were tracked via electrodes by populations of hippocampal cells that constantly changed over time despite recording very similar experiences. This revealed for the first time the maze runs during which ripples occurred during waking pauses and then were replayed during sleep.

    Sharp wave-ripples were typically recorded when a mouse paused to enjoy a sugary treat after each maze run. The consumption of the reward, say the authors, prepared the brain to switch from an exploratory to an idle pattern so that sharp wave-ripples could occur.

    Using dual-sided silicon probes, the research team was able to record up to 500 neurons simultaneously in the hippocampus of animals during maze runs. This in turn created a challenge because data becomes exceedingly complex the more neurons are independently recorded. 

    To gain an intuitive understanding of the data, visualize neuronal activity, and form hypotheses, the team successfully reduced the number of dimensions in the data, in some ways like converting a three-dimensional image into a flat one, and without losing the data’s integrity.

    “We worked to take the external world out of the equation, and looked at the mechanisms by which the mammalian brain innately and subconsciously tags some memories to become permanent,” says first author Wannan (Winnie) Yang, PhD, a graduate student in Buzsáki’s lab, in a release. “Why such a system evolved is still a mystery, but future research may reveal devices or therapies that can adjust sharp wave-ripples to improve memory, or even lessen recall of traumatic events.”