<table style="border:1px solid #adadad; background-color: #F3F1EC; color: #666666; padding:8px; -webkit-border-radius:4px; border-radius:4px; -moz-border-radius:4px; line-height:16px; margin-bottom:6px;" width="100%">
<tbody>
<tr>
<td><span style="font-family:Helvetica, sans-serif; font-size:20px;font-weight:bold;">PsyPost – Psychology News</span></td>
</tr>
<tr>
<td> </td>
</tr>
</tbody>
</table>
<table style="font:13px Helvetica, sans-serif; border-radius:4px; -moz-border-radius:4px; -webkit-border-radius:4px; background-color:#fff; padding:8px; margin-bottom:6px; border:1px solid #adadad;" width="100%">
<tbody>
<tr>
<td><a href="https://www.psypost.org/persistent-apathy-predicts-faster-functional-decline-in-alzheimers-disease/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Persistent apathy predicts faster functional decline in Alzheimer’s disease</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Jul 17th 2025, 10:00</div>
<div style="font-family:Helvetica, sans-serif; color:#494949;text-align:justify;font-size:13px;">
<p><p>A new study sheds light on how behavioral symptoms are related to daily functioning in people with Alzheimer’s disease. Researchers found that individuals with persistent apathy—characterized by diminished motivation and reduced emotional engagement—tend to experience a faster loss of independence over time. While people with Alzheimer’s disease can show different clusters of behavioral symptoms, apathy stood out as a particularly strong predictor of functional decline. The findings were published in <em><a href="https://doi.org/10.1176/appi.neuropsych.20250015" target="_blank">The Journal of Neuropsychiatry and Clinical Neurosciences</a></em>.</p>
<p>Alzheimer’s disease is a progressive brain disorder that affects memory, thinking, and behavior. As the disease advances, people often lose the ability to perform everyday tasks, such as managing finances or preparing meals. While memory loss is the most widely recognized symptom, many people with Alzheimer’s also experience changes in mood and behavior. These changes, known as neuropsychiatric symptoms, can include apathy, depression, agitation, delusions, and hallucinations. These symptoms can be distressing for both patients and caregivers and have been linked to worse outcomes, such as faster cognitive decline and earlier nursing home placement.</p>
<p>To better understand how behavioral symptoms influence the course of Alzheimer’s disease, researchers from multiple institutions analyzed data from the National Alzheimer’s Coordinating Center, which compiles information from Alzheimer’s research centers across the United States. They wanted to know whether clusters of behavioral symptoms—such as people who mainly show depression and apathy, or those who exhibit multiple symptoms—were linked to differences in how quickly someone’s ability to function declines over time. They also asked whether specific symptoms might be more predictive of decline than broader symptom patterns.</p>
<p>“We have been studying neuropsychiatric symptoms in dementia for some time and have always wondered if specific symptoms or specific individuals who manifest clusters of symptoms may be suitable targets for interventions for preventing and delaying functional decline,” said study author Carolyn W. Zhu, a professor and data core lead at the Alzheimer’s Disease Research Center at the Icahn School of Medicine at Mount Sinai.</p>
<p>The researchers included nearly 9,800 participants who had been diagnosed with either mild cognitive impairment or Alzheimer’s disease at the start of the study. All participants were over the age of 50 and had at least one follow-up visit over the course of up to five years. People with very mild or very severe dementia at the start were excluded. The average age of the sample was about 74 years old, and most participants were white and highly educated.</p>
<p>To track everyday functioning, researchers used a standard tool called the Functional Assessment Questionnaire. This questionnaire asks whether a person has difficulty with common activities, such as handling money, remembering appointments, or cooking. The responses are provided by someone who knows the participant well, such as a spouse or adult child. Higher scores on this scale indicate more difficulty with daily functioning.</p>
<p>Behavioral symptoms were assessed by expert clinicians at each visit. These clinicians reported whether the participant was currently showing symptoms such as apathy, depression, hallucinations, or agitation. The researchers looked at whether these symptoms were present at baseline, and whether they appeared intermittently or persistently over time.</p>
<p>Using a statistical method called latent class analysis, the team identified four main clusters of participants based on their symptom profiles at the start of the study. The largest group, which made up nearly half the sample, had few or no behavioral symptoms. A second group, comprising about 35% of participants, had high rates of apathy and depression. A third group, about 13%, showed multiple symptoms including agitation and irritability, but not hallucinations. The smallest group—just under 3%—showed high levels of all symptoms, including psychosis, and was labeled the “complex” group.</p>
<p>These symptom clusters were associated with differences in how well people were functioning at the beginning of the study. People in the asymptomatic group had better functional abilities than those in the other groups. However, over time, the rate of decline in functioning did not differ significantly between the groups. In other words, being in a certain symptom cluster did not predict how fast someone would lose the ability to carry out everyday tasks.</p>
<p>To look more closely at individual symptoms, the researchers then examined whether the presence and persistence of each symptom predicted functional decline, even after accounting for which cluster the person belonged to. Apathy stood out as a key factor. People who were rated as persistently apathetic over time experienced a much faster rate of functional decline than those who never had apathy. </p>
<p>Even those who showed apathy intermittently declined more quickly than those who never had the symptom. In contrast, other symptoms such as depression, disinhibition, and irritability were not linked to faster decline once apathy and other factors were taken into account.</p>
<p>The study also found that delusions and agitation were linked to faster decline, but the effect was smaller than that seen for apathy. Hallucinations were associated with worse function at baseline, but not with a faster rate of decline over time.</p>
<p>To better understand whether these findings applied to people in earlier versus later stages of the disease, the researchers conducted a separate analysis of people with mild cognitive impairment and those with full dementia. The results were consistent: apathy predicted faster decline in both groups, regardless of other symptoms.</p>
<p>“Our results showed that after taking into consideration other individual symptoms and different symptom clusters, apathy continued to be strongly associated with accelerated functional decline in dementia patients,” Zhu told PsyPost.</p>
<p>These findings support earlier research showing that apathy is a common and persistent symptom in Alzheimer’s disease and may play a central role in the progression of the illness. Apathy affects more than motivation—it can reduce a person’s interest in social engagement, make them less likely to initiate activities, and impair their ability to follow through on tasks. This diminished drive can make it harder to maintain independence in everyday life, even in the absence of severe memory problems.</p>
<p>Brain imaging studies suggest that apathy is linked to dysfunction in specific brain regions involved in motivation and reward processing, such as the prefrontal cortex and basal ganglia. Some researchers have proposed that apathy may reflect damage to circuits that are distinct from those that underlie memory loss, which may help explain why it can be an early and independent predictor of functional decline.</p>
<p>The results of this study suggest that clinicians should pay particular attention to signs of apathy in people with Alzheimer’s disease or mild cognitive impairment. While other symptoms like agitation or hallucinations often draw more attention because they are disruptive or alarming, apathy may have a more consistent impact on a person’s ability to function independently over time.</p>
<p>There are some limitations to the study. The participants were drawn from specialized research centers and were generally more educated and healthier than the general population. The assessments of symptoms were based on clinician judgment, which, while informed, may vary between clinicians. In addition, the study’s observational design means that it can identify associations but not prove causation.</p>
<p>Still, the large sample size, long follow-up period, and detailed symptom tracking provide strong support for the conclusion that apathy plays a significant role in functional decline. This finding has practical implications. Apathy is relatively easy to observe and measure in clinical settings. Detecting it early may help identify people at higher risk of losing independence and offer a window of opportunity for intervention.</p>
<p>“It is perhaps unsurprising that apathy, which is characterized by reduced motivation and independent goal-directed activity, should be so strongly associated with functional decline over time,” Zhu said. “However, its impact on function, which appears to be more significant than other more dramatic neuropsychiatric symptoms that often dominate clinicians’ time and attention, is likely under-appreciated in many clinical settings.”</p>
<p>“We believe that enhancing medical education for primary care providers who serve most patients with dementia, to improve awareness of neuropsychiatric symptoms in those with mild cognitive impairment and dementia may be a worthwhile strategy to providing patient centered care with better prediction of prognosis and targeted approaches for treatment and management.”</p>
<p>The study, “<a href="https://doi.org/10.1176/appi.neuropsych.20250015" target="_blank">Understanding the Role of Neuropsychiatric Symptom in Functional Decline in Alzheimer’s Disease</a>,” was authored by Carolyn W. Zhu, Lon S. Schneider, Laili Soleimani, Judith Neugroschl, Hillel T. Grossman, Corbett Schimming, and Mary Sano.</p></p>
</div>
<div style="font-family:Helvetica, sans-serif; font-size:13px; text-align: center; color: #666666; padding:4px; margin-bottom:2px;"></div>
</td>
</tr>
</tbody>
</table>
<table style="font:13px Helvetica, sans-serif; border-radius:4px; -moz-border-radius:4px; -webkit-border-radius:4px; background-color:#fff; padding:8px; margin-bottom:6px; border:1px solid #adadad;" width="100%">
<tbody>
<tr>
<td><a href="https://www.psypost.org/yoga-nidra-meditation-reduces-stress-and-reshapes-cortisol-rhythms-study-finds/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Yoga nidra meditation reduces stress and reshapes cortisol rhythms, study finds</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Jul 17th 2025, 08:00</div>
<div style="font-family:Helvetica, sans-serif; color:#494949;text-align:justify;font-size:13px;">
<p><p>A new study finds that practicing a guided meditation known as yoga nidra can reduce stress, anxiety, and depression. The research, published in the journal <em><a href="https://doi.org/10.1002/smi.70049" target="_blank">Stress and Health</a></em>, also shows that even short, 11-minute daily sessions can produce measurable changes in the body’s primary stress hormone, while longer 30-minute sessions may offer additional benefits for mindfulness and physiological regulation.</p>
<p>Yoga nidra, sometimes called “yogic sleep,” is a guided meditation technique that brings practitioners into a deeply relaxed state while remaining conscious. The practice typically involves lying down, slowing the breath, setting intentions, and moving through stages of body awareness and imagery. In recent years, it has gained popularity under the label “non-sleep deep rest” and has been studied for its effects on emotional regulation, sleep, and anxiety. Although past studies suggested psychological benefits, researchers wanted to determine whether yoga nidra could also change physiological markers of stress, like cortisol, especially in a large, well-controlled study.</p>
<p>“I practice yoga nidra myself almost daily and find it incredibly helpful—not only for calming down, but also for gaining clarity and creative ideas through that short, conscious pause,” said study author <a href="https://www.psychologie-im-inntal.de/" target="_blank">Esther N. Moszeik</a>, a research associate at <a href="https://www.unibw.de/hum-psychologie/ppd/personen/moszeik" target="_blank">the University of the Bundeswehr Munich</a>.</p>
<p>“In a previous study, we had already found that even 11 minutes of yoga nidra improved subjective sleep quality and mood. This follow-up study was designed to go one step further: we included biological stress markers, compared two yoga nidra formats, and added an active control group with music to better isolate the effects. I was also curious whether individual personality traits might influence who benefits most from which version—and how we find better matches between people and interventions.”</p>
<p>The researchers focused on cortisol, the body’s main stress hormone. The natural daily rhythm of cortisol, including a sharp rise upon waking and a gradual decline throughout the day, is a key indicator of the body’s stress response system. Deviations from this pattern have been linked to chronic stress and mental health issues. The research team set out to determine if yoga nidra could help regulate this biological rhythm and improve psychological well-being at the same time.</p>
<p>To investigate these questions, the researchers conducted an online randomized controlled trial. They recruited a large sample of 362 German-speaking adults and randomly assigned them to one of four groups. The first experimental group practiced an 11-minute version of yoga nidra. The second experimental group practiced a longer, 30-minute version. </p>
<p>To see if yoga nidra had unique effects beyond simple relaxation, a third group served as an active control, listening to 10 minutes of calming instrumental music. A fourth group was a waitlist control, receiving no intervention during the study period, which served as a baseline for comparison. Participants in the intervention groups were asked to engage in their assigned practice, ideally daily, for two months using pre-recorded audio files. </p>
<p>To measure the effects, all participants completed a series of online questionnaires before the intervention began, immediately after the two-month period, and again at a three-month follow-up to assess any lasting changes. These questionnaires measured perceived stress, symptoms of anxiety and depression, the tendency to ruminate on negative thoughts, overall satisfaction with life, and sleep quality. They also assessed five different facets of mindfulness, such as the ability to act with awareness and accept thoughts without judgment. </p>
<p>In addition, a subset of 229 participants provided saliva samples to measure their cortisol levels. They collected five samples at specific times over two consecutive days, which allowed the researchers to map each person’s daily cortisol pattern, including the morning rise and the slope of decline throughout the day.</p>
<p>The results of the study revealed that both forms of yoga nidra had a positive impact on mental health. When compared to the waitlist control group, the 11-minute yoga nidra practice led to reductions in stress, anxiety, depression, and rumination. Participants in this group also reported an increase in their satisfaction with life. </p>
<p>While these effects were statistically significant, they were small in size, representing improvements of about 8% to 16% of a standard deviation. However, even small effects can be meaningful when they come from a low-cost, easily accessible intervention. When compared against the active control group that listened to music, the 11-minute yoga nidra practice showed a distinct advantage in one area: it significantly reduced symptoms of depression.</p>
<p>“One surprise was that even the brief 11-minute meditation produced noticeable benefits – we often assume longer is better, but the short daily practice made a difference,” Moszeik told PsyPost. “We also found hints that not everyone responds in the same way: certain personality traits seemed to amplify the benefits of the meditation: for example, very conscientious individuals showed bigger gains than others and people high in neuroticism appeared to benefit especially strongly from the longer, 30-minute sessions.”</p>
<p>When comparing the two lengths of yoga nidra, the researchers found that the 30-minute version was not universally superior to the 11-minute one. The main difference was that the longer practice led to a greater increase in one specific facet of mindfulness known as “acting with awareness.” This refers to the ability to remain focused on one’s present actions and be less easily distracted. </p>
<p>However, the 30-minute practice did show broader benefits when compared to the control groups. For example, when compared to the waitlist group, the 30-minute session produced significant reductions in stress, anxiety, depression, rumination, and sleep disturbances. It also produced a noteworthy biological change: it resulted in a flatter cortisol awakening response. This means the typical sharp spike of the stress hormone in the morning was less pronounced, suggesting a more relaxed start to the day and less anticipatory stress.</p>
<p>For participants in the 11-minute group, practicing more frequently was associated with changes in their cortisol patterns. Regular practice was linked to a reduction in total cortisol output throughout the day and a steeper decline in the hormone from morning to evening, a pattern generally associated with better health and well-being. This suggests that consistency is a key component for achieving biological benefits, even with a very short practice. </p>
<p>For the 30-minute group, more frequent practice was associated with reduced rumination and increased mindfulness, but it was also linked to a higher cortisol awakening response. The researchers speculate that for those engaging in longer, more regular practice, the meditation may transition from being primarily relaxing to being more energizing or activating over time.</p>
<p>“The main takeaway is that a simple daily relaxation practice like yoga nidra can have real, measurable benefits for your well-being,” Moszeik said. “We observed small but meaningful improvements in stress and mood for people who practiced yoga nidra compared to those who didn’t, and even their cortisol (a key stress hormone) showed a healthier daily rhythm. It’s important to know that cortisol isn’t purely ‘bad’ – in fact, we need it to wake up and get energized – but chronic stress can throw its cycle out of balance. Our findings suggest that taking just a few minutes to deeply relax each day helps keep your cortisol levels in a better balance over the day, which is linked to feeling calmer and more resilient.”</p>
<p>The study has several strengths, including its large and diverse sample, the use of a randomized controlled design with an active control group, and the inclusion of a biological marker for stress. Administering the intervention online also demonstrates its potential for widespread, low-cost implementation. However, the study also has some limitations. The online format meant that participants did not receive personal guidance or support, which can be an important part of learning a new meditation practice.</p>
<p>“The improvements we saw were statistically significant but quite small in magnitude,” Moszeik noted. “In other words, yoga nidra isn’t a quick fix or miracle cure – it’s more like a gentle and steady nudge toward feeling better. Another limitation is that our study relied on participants practicing on their own at home, so we had to trust their self-reports about how often and how well they did the meditation. We also mainly studied healthy adults who were interested enough to sign up for a meditation trial, which means the results might not generalize to everyone. Finally, while we did include a follow-up, we only tracked outcomes for a few months, so we don’t yet know how durable these effects are in the long run.”</p>
<p>Looking ahead, the research team aims to build on these findings by exploring how to personalize these kinds of interventions. </p>
<p>“Our results hinted that factors like personality could moderate how much someone benefits, so one next step is to figure out which types of people respond best to which techniques,” Moszeik explained. “For instance, maybe some individuals thrive with a short daily practice while others need a longer session or a different kind of meditation – understanding those differences can help tailor stress-management programs to the person. </p>
<p>“We’re also interested in seeing what happens if people continue practicing yoga nidra beyond two months: Do the benefits accumulate or reach a plateau? And do these changes in cortisol and well-being translate into tangible health outcomes (like better sleep, focus, or fewer stress-related symptoms) over time? Ultimately, our goal is to make mind-body interventions like this as effective and accessible as possible, by learning how to match the right practice to the right person.”</p>
<p>“I’d add that it was encouraging to see both the short and long versions of yoga nidra have benefits, which means people can choose what fits their schedule and still gain something,” Moszeik said. “Even a brief 11-minute daily routine was enough to improve some mental health measures, especially for parents, people in leadership positions, and older men. On the other hand, the 30-minute version did provide a bit of an extra boost in certain areas – for example, it seemed to further calm the spike of cortisol we normally get after waking up in the morning.” </p>
<p>“So, there’s flexibility: you don’t necessarily need a huge time commitment to help manage stress, but if you can set aside a bit longer, you might see additional advantages. Overall, we hope this study shows that taking time out for deep relaxation isn’t just a nice indulgence – it’s a practical tool that can make a positive difference in your daily life.”</p>
<p>The study, “<a href="https://doi.org/10.1002/smi.70049" target="_blank">The Effects of an Online Yoga Nidra Meditation on Subjective Well-Being and Diurnal Salivary Cortisol: A Randomised Controlled Trial</a>,” was authored by Esther N. Moszeik, Nicolas Rohleder, and Karl-Heinz Renner.</p></p>
</div>
<div style="font-family:Helvetica, sans-serif; font-size:13px; text-align: center; color: #666666; padding:4px; margin-bottom:2px;"></div>
</td>
</tr>
</tbody>
</table>
<table style="font:13px Helvetica, sans-serif; border-radius:4px; -moz-border-radius:4px; -webkit-border-radius:4px; background-color:#fff; padding:8px; margin-bottom:6px; border:1px solid #adadad;" width="100%">
<tbody>
<tr>
<td><a href="https://www.psypost.org/women-favor-men-with-attractive-faces-when-making-social-bargaining-decisions/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Women favor men with attractive faces when making social bargaining decisions</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Jul 16th 2025, 14:00</div>
<div style="font-family:Helvetica, sans-serif; color:#494949;text-align:justify;font-size:13px;">
<p><p>A study in China found that women favor men with attractive faces and those showing positive social interest (i.e., who say they like them) when making social bargaining decisions. In an ultimatum game, participants were more likely to accept offers from such men. In a third-party punishment dictator game, they rated fair offers from them as more reasonable. However, the effects varied depending on the context. The research was published in <a href="https://doi.org/10.3390/bs14121154"><em>Behavioral Sciences</em></a>.</p>
<p>Attractive individuals often experience better social outcomes than their less attractive peers, even when other qualifications are equal. This phenomenon is known as the beauty premium. Research shows that physically attractive people are perceived as more competent, trustworthy, and likable—traits that are often unrelated to appearance. These perceptions can lead to advantages in hiring, promotions, and salaries, especially in customer-facing or high-status roles.</p>
<p>Studies have also found that more attractive individuals tend to earn higher incomes than their less attractive peers with similar qualifications. Beauty can influence judicial outcomes too: attractive defendants are more likely to receive lenient sentences for nonviolent crimes. In social settings, attractiveness can contribute to greater popularity and social support, particularly during adolescence and early adulthood.</p>
<p>Study authors Junchen Shang and Yizhuo Zhang sought to explore how attractiveness and social interest (whether someone appears to like you) interact in shaping decisions about fairness. They conducted an experiment in which women played two economic games—the three-person ultimatum game and the third-party punishment dictator game—while being exposed to male proposers who differed in facial attractiveness, vocal attractiveness, and expressions of social interest (e.g., saying “I like you” vs. “I don’t like you”).</p>
<p>The researchers hypothesized that participants would be more likely to accept offers from proposers with attractive faces, attractive voices, or who expressed positive social interest. Similarly, they expected that participants would perceive unfair allocations as more reasonable if they were proposed by individuals with those traits.</p>
<p>Participants were 70 female students at Southeast University in China who were not majoring in economics or psychology, making them less likely to be familiar with the purpose of economic game experiments. Their average age was 21 years.</p>
<p>Each participant completed both games. In the ultimatum game, a fictional male proposer suggested how to divide 12 Chinese yuan (approximately $1.70) among himself, the participant, and a third party. The participant then chose whether to accept or reject the offer. In the punishment game, participants observed a fictional proposer dividing money with a recipient and rated how reasonable the allocation was and how strongly they wanted to punish the proposer.</p>
<p>The proposers varied in facial and vocal attractiveness and in their expressions of social interest. These cues were presented through photographs, audio clips, and simple statements like “I like you” or “I don’t like you.”</p>
<p>Results showed that participants were more likely to accept proposals from men with attractive faces or attractive voices, especially when the proposers expressed positive social interest. Acceptance was also higher when the offer was perceived as fair, but even unfair offers were more likely to be accepted when made by attractive or socially interested proposers.</p>
<p>In the punishment game, participants rated fair offers from attractive-faced proposers as the most reasonable. However, when men with attractive faces and voices expressed positive interest but made unfair offers, they were rated as particularly unreasonable—suggesting that the inconsistency between friendly cues and selfish behavior was especially jarring. By contrast, unfair offers from men who said “I don’t like you” were rated as less unreasonable when those men also had attractive faces and voices.</p>
<p>“The present study demonstrated the effect of facial attractiveness, vocal attractiveness, and social interest on females’ fairness considerations in two three‑person bargaining games when participants were involved in money distribution or they acted as an interest‑ free third party. Although we observed a more generous beauty premium effect, the pro-attractiveness bias was shown to be stronger for faces rather than voices. Moreover, the effects of attractiveness and social interest were heterogenous across different level of fairness and different economic games,” the study authors concluded.</p>
<p>The study sheds light on the effects of attractiveness on social decisions. However, it should be noted that the study involved games in which players distributed very small amounts of money. Results might not be the same if the amounts were higher.</p>
<p>The paper, “<a href="https://doi.org/10.3390/bs14121154">Beauty and Social Interest Matter: Effects of Male’s Facial Attractiveness, Vocal Attractiveness and Social Interest on Female’s Decisions in Three‑Person Games,</a>” was authored by Junchen Shang and Yizhuo Zhang.</p></p>
</div>
<div style="font-family:Helvetica, sans-serif; font-size:13px; text-align: center; color: #666666; padding:4px; margin-bottom:2px;"></div>
</td>
</tr>
</tbody>
</table>
<table style="font:13px Helvetica, sans-serif; border-radius:4px; -moz-border-radius:4px; -webkit-border-radius:4px; background-color:#fff; padding:8px; margin-bottom:6px; border:1px solid #adadad;" width="100%">
<tbody>
<tr>
<td><a href="https://www.psypost.org/caffeine-increases-brain-complexity-during-sleep-study-shows/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Caffeine increases brain complexity during sleep, study shows</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Jul 16th 2025, 12:00</div>
<div style="font-family:Helvetica, sans-serif; color:#494949;text-align:justify;font-size:13px;">
<p><p>A new study published in <em><a href="https://www.nature.com/articles/s42003-025-08090-z" target="_blank" rel="noopener">Communications Biology</a></em> has found that caffeine reshapes the brain’s electrical activity during sleep, increasing complexity and nudging neural networks toward a more excitable and dynamic state. These changes were especially pronounced during non-REM sleep and in younger adults, suggesting that age and sleep stage both influence how the brain responds to caffeine at night.</p>
<p>The findings shed light on how caffeine influences the brain’s internal rhythms beyond simply keeping people awake, offering new insights into its potential effects on sleep quality and brain function.</p>
<p>Caffeine is the most widely consumed psychoactive stimulant in the world, commonly found in coffee, tea, soda, chocolate, and many medications. While its alerting effects are well known, scientists have yet to fully understand how caffeine alters brain activity during sleep—a time when the brain undergoes important restorative and regulatory processes.</p>
<p>The new study aimed to uncover how caffeine changes the structure and complexity of brain activity during different sleep stages. Researchers were particularly interested in whether caffeine affects the brain’s “criticality”—a theoretical balance between order and chaos believed to optimize information processing.</p>
<p>Previous work has shown that in waking states, higher brain complexity is associated with better cognitive functioning. But it remained unclear how caffeine might influence this complexity during sleep, when the brain’s dynamics naturally shift toward lower activity and more regular patterns.</p>
<p>“The widespread use of caffeine among the public makes this topic an important health consideration. Understanding how caffeine affects sleep architecture and brain dynamics, as measured through EEG, can help clarify its impact on neural health,” said study author Philipp Thölke, a research trainee in the Cognitive and Computational Neuroscience Laboratory (CoCo Lab) at the University of Montreal.</p>
<p>To explore these questions, the researchers analyzed the brain activity of 40 healthy adults between the ages of 20 and 58. Participants spent two separate nights in a sleep laboratory—one after ingesting 200 mg of caffeine (roughly equivalent to two cups of coffee) and one after ingesting a placebo. The study used a double-blind crossover design, meaning neither the participants nor the researchers knew which condition was administered on a given night.</p>
<p>All participants were free of medical and psychiatric conditions, had moderate daily caffeine habits, and abstained from caffeine after noon on the days of testing. Their sleep was monitored using EEG, which records electrical signals from the brain through electrodes placed on the scalp. The researchers divided sleep into two main categories for analysis: non-REM (which includes light and deep sleep) and REM (the stage associated with dreaming).</p>
<p>The research team extracted a wide range of features from the EEG data, including both traditional frequency-based measures and more sophisticated metrics that capture the unpredictability and information content of the signal. They focused on several markers of brain complexity, including entropy (a measure of randomness), Lempel-Ziv complexity (which quantifies how compressible a signal is), and long-range temporal correlations (which assess how similar a signal is to itself over time).</p>
<p>They also examined the brain’s power spectrum—the distribution of electrical activity across different frequencies. This spectrum has two components: oscillatory rhythms, like the familiar delta and alpha waves, and an aperiodic background signal often referred to as “1/f noise.” The slope of this aperiodic signal is believed to reflect the balance between neural excitation and inhibition. A flatter slope is thought to indicate greater neural excitation and closer proximity to a “critical state,” where the brain is most responsive and adaptable.</p>
<p>The results showed that caffeine produced widespread and consistent effects on brain complexity during non-REM sleep. Compared to placebo, caffeine increased several measures of entropy and complexity, and it reduced long-range temporal correlations. It also led to a flattening of the aperiodic slope in the power spectrum. Together, these findings suggest that caffeine shifts the sleeping brain toward a more excitable and dynamic regime, one that resembles the critical state associated with wakefulness and cognitive engagement.</p>
<p>Interestingly, these changes were far more pronounced during non-REM sleep than during REM sleep. In REM, the effects of caffeine were smaller and more localized, mainly appearing in occipital (visual) regions. One measure—spectral entropy—stood out as the most effective at distinguishing caffeine from placebo in non-REM sleep, achieving a classification accuracy of 75% when used in machine learning models. This performance surpassed all traditional EEG measures of oscillatory power.</p>
<p>“Caffeine delays but does not prevent sleep, so even though we can sleep under the influence of caffeine, the brain and therefore also sleep is impacted by the drug,” Thölke told PsyPost. “It leads to shallower sleep with increased information processing during the sleep stages where the brain normally enters deep restorative rest.”</p>
<p>The researchers also examined how age affected caffeine’s influence on the brain. In general, younger adults (ages 20–27) showed stronger responses to caffeine during REM sleep compared to middle-aged adults (ages 41–58). These age differences were especially apparent in measures of entropy and criticality. However, during non-REM sleep, the effects of caffeine were similarly robust across both age groups.</p>
<p>One possible explanation for the age-related difference in REM sensitivity is that older adults have fewer adenosine receptors. Adenosine is a chemical that builds up in the brain during waking hours and promotes sleepiness. Caffeine works by blocking these receptors, reducing sleep pressure and promoting alertness. If older adults have fewer receptors, the blocking effect of caffeine may be weaker, especially in REM sleep when adenosine levels are already low.</p>
<p>Another important aspect of the study was the use of multiple analysis techniques. In addition to traditional statistics, the researchers used machine learning models to classify whether EEG data came from the caffeine or placebo condition. These models reinforced the main findings and highlighted that complexity-related features were more informative than conventional measures of oscillatory power.</p>
<p>To ensure that their results weren’t simply due to changes in sleep duration or structure, the researchers performed a control analysis. They equated the number of EEG samples from each sleep stage across both conditions. The results remained consistent, suggesting that the observed changes were due to caffeine’s impact on brain activity rather than differences in the amount of sleep.</p>
<p>As with all research, there are limitations. “Participants of the study were healthy, which does not allow for generalization to clinical populations,” Thölke noted. “As a result, from the current study it is difficult to determine whether the observed effects would hold in individuals with neurological or psychiatric conditions.”</p>
<p>In addition, the study focused on short-term, nighttime caffeine intake and did not assess the effects of chronic use or withdrawal. Lastly, while the study draws on evidence linking EEG features to neural excitation and inhibition, it does not directly measure neurotransmitter activity or receptor binding, leaving some mechanistic questions open.</p>
<p>Future research could explore how these changes affect cognitive processes that depend on sleep, such as memory consolidation, emotional regulation, and learning. Studies in clinical populations could also help determine whether caffeine’s impact on sleep-related brain activity differs in people with insomnia, depression, or neurodegenerative conditions like Alzheimer’s disease.</p>
<p>The study, “<a href="http://caffeine%20induces%20age-dependent%20increases%20in%20brain%20complexity%20and%20criticality%20during%20sleep">Caffeine induces age-dependent increases in brain complexity and criticality during sleep</a>,” was authored by Philipp Thölke, Maxine Arcand-Lavigne, Tarek Lajnef, Sonia Frenette, Julie Carrier, and Karim Jerbi.</p></p>
</div>
<div style="font-family:Helvetica, sans-serif; font-size:13px; text-align: center; color: #666666; padding:4px; margin-bottom:2px;"></div>
</td>
</tr>
</tbody>
</table>
<p><strong>Forwarded by:<br />
Michael Reeder LCPC<br />
Baltimore, MD</strong></p>
<p><strong>This information is taken from free public RSS feeds published by each organization for the purpose of public distribution. Readers are linked back to the article content on each organization's website. This email is an unaffiliated unofficial redistribution of this freely provided content from the publishers. </strong></p>
<p> </p>
<p><s><small><a href="#" style="color:#ffffff;"><a href='https://blogtrottr.com/unsubscribe/565/DY9DKf'>unsubscribe from this feed</a></a></small></s></p>