Children's caffeine habits linked to shorter sleep and brain differences

 

• Young people aged 9 to 11 who consumed more caffeine had slightly lower surface area across the brain's outer layer 

• Children who had more caffeine also slept less, and this shorter sleep was linked to brain differences, and ultimately mental health 

• Children with higher caffeine intake reported more mental health problems six months later 

• Associations between caffeine consumption and brain structure emerged as low as 1 cup per week 

Young people who consume more caffeine, mostly from soft drinks, sleep less and show small differences in how their brains are developing, according to a study led by researchers at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King's College London. 

The researchers drew on data from 9,632 children aged nine to eleven taking part in the Adolescent Brain Cognitive Development (ABCD) Study, which follows the brain development and health of young people across the US. Each child said how many caffeinated drinks they usually had in a week, whether coffee, tea or soft drinks, with parents reporting how long the children usually sleep on average. MRI scans then measured thickness and surface area of the cortex, the brain's folded outer layer, which plays a part in cognitive processing, decision making, attention and emotions, among other important functions. 

The children were then asked to report back on their mental health 6 and 18 months later with the results showing that greater caffeine consumption is associated with lower surface area across the cortex, even after we adjust for household socioeconomic circumstances like parental educational attainment and income. The pattern showed up in 22 separate regions, spanning all four lobes of the brain. These effects were largely driven by the consumption of soft drinks, which were the biggest source of caffeine in the study. Differences in overall surface area showed up from as little as one caffeinated drink a week, compared with none.  

Dr Divyangana Rakesh, senior author of the study from the IoPPN at King’s College London, said:  

“Caffeine is such a normal part of daily life that it's easy to forget young people are consuming it too. Studies have found that two-thirds of adolescents consume caffeine at least once a week. Despite it being a psychoactive substance, it is completely unregulated. 

“We found that even fairly low levels of intake were linked to small differences in brain structure and later mental health, and lower sleep duration seems to be an important underlying link. Although we cannot comment on causality, our results do suggest that both caffeine intake, including from soft drinks, and sleep are worth paying attention to when we think about young people's mental health."  

The researchers then looked at what might connect caffeine to differences in brain structure. Young people who consumed more caffeine slept less, which was in turn linked to lower surface area. Together, shorter sleep and lower surface area partly explained the link between higher caffeine intake and more mental health problems six months later, including problems with attention, mood and behaviour. At 18 months, only the link through overall surface area was still there. 

Jiayi Zheng, first author of the study from the IoPPN at King’s College London, said:  
 
"Soft drinks contain a lot of sugar and often go hand in hand with less healthy lifestyle habits and more risk-taking behaviours, so we can't yet separate the role of caffeine from everything else that comes with them. That's the next question we want to answer, ideally with more precise measures of what young people drink, when they drink it and how well they sleep."  

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Journal

Biological Psychiatry Cognitive Neuroscience and Neuroimaging

DOI

10.1016/j.bpsc.2026.09.011 

Exercise should be prescribed as a core component of cardiovascular care

 

Exercise should be prescribed as a foundational component of cardiovascular disease (CVD) prevention and treatment, according to a new American College of Cardiology Scientific Statement published today in JACC, its flagship journal. The statement emphasizes that the greatest reduction in cardiovascular risk occurs when sedentary individuals become even modestly more active, and the best exercise prescription is one that is safe, individualized, achievable and sustainable over time.

Low cardiorespiratory fitness is a predictor of future CVD that is on par with traditional cardiovascular risk factors such as smoking, hypertension, high cholesterol and diabetes; however, exercise prescription is inconsistently integrated into routine cardiovascular care. The scientific statement highlights extensive evidence showing that regular physical activity, structured exercise and cardiorespiratory fitness improve exercise capacity, reduce hospitalization and enhance quality of life.

“The most important message is that some activity is better than none,” Jonathan N. Myers, PhD, a health research scientist with the Palo Alto VA Healthcare system and chair of the statement’s writing committee, said. “Patients do not need to become athletes to improve their cardiovascular health. Small increases in physical activity can produce meaningful benefits, particularly for those who are currently inactive.”

For example, the statement highlights growing evidence that meaningful cardiovascular benefits can be achieved with fewer than 10,000 daily steps. Data suggest that approximately 5,000 to 7,000 steps/day are associated with clinically important improvements and substantial reductions in cardiovascular and all-cause mortality for many adults.

Key recommendations and considerations in the statement include:

• Exercise prescriptions should be individualized based on a patient's cardiovascular condition, functional capacity, symptoms, treatment goals and preferences.
• Resistance training should complement aerobic exercise for most adults.
• Wearable devices and virtual or home-based rehabilitation programs may help support exercise participation and long-term adherence, particularly when combined with structured programs such as cardiac rehabilitation.
• Routine exercise testing is not required before starting exercise for most asymptomatic or clinically stable individuals but can provide valuable information for individualized exercise prescription when clinically appropriate.
• Cardiac rehabilitation remains first-line treatment for many patients with CVD and access should be expanded. While insurance reimbursement remains a barrier to entry for many, individualized exercise prescriptions should be provided to those with known CVD who are unable to participate in formal cardiac rehabilitation.

The authors also call for greater integration of exercise counseling into routine cardiovascular care, expanded access to cardiac rehabilitation and additional research on strategies that improve long-term adherence to physical activity.

“Exercise is one of the most effective therapies available for preventing and managing CVD, yet it remains underutilized in routine care,” Myers said. “This statement provides clinicians with practical tools to help patients safely incorporate exercise into their treatment plans and improve long-term cardiovascular health.”

Ultra-processed food intake linked to silent strokes in healthy middle-aged adults

  Healthy adults who eat high amounts of ultra-processed food, like packaged snack foods, sugary breakfast cereals, soft drinks, instant noodles, and ready-to-eat frozen meals, are more likely to have signs of damage to the brain that may increase the chances of clinical stroke and future memory problems.

Researchers used magnetic resonance imaging (MRI) to scan the brains of nearly 9,000 people and detected tiny areas of damage more frequently in participants who ate the most ultra-processed food compared to those who ate the least. Participants with the highest intake were 40 per cent more likely to show these changes, which produce no obvious symptoms but are considered early warning signs that can appear years before a stroke or memory problems begins.

"I would not have expected this finding, frankly. We studied middle-aged Canadians who had no heart problems and reported no other health concerns,” said Russell J. de Souza, first author of the study and an associate scientist at the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences, and associate professor in Health Research Methods, Evidence, and Impact and the Heersink School of Global Health and Social Medicine at McMaster University.

“Usually, this kind of damage is associated with conditions we hear about and treat at a much older age."

Published in JAMA Network Open on Oct. 15, 2026, the PHRI led study enrolled Canadians between the ages of 35 and 69 with no history of heart disease from communities across Canada.

Participants who ate the most ultra-processed food also carried more body fat and more deep belly fat than those who ate the least. This type of abdominal fat is linked to inflammation and blood vessel damage that can also reach the brain.

The association between ultra-processed food and brain damage appeared stronger among women. Those in the highest consumption group were nearly twice as likely to show signs of brain damage compared with those in the lowest group.

"Our findings suggest that the link between diet and brain health may be detectable before people experience noticeable problems with memory or thinking," said Sonia Anand, senior author of the study and senior scientist at PHRI. “This adds to the growing evidence that what Canadians eat in their 30s, 40s, 50s and 60s shapes their brain health later in life.”

Researchers classified foods according to the extent and purpose of industrial processing used in their production. Ultra-processed foods are often high in sodium, added sugars, and saturated fats, while providing relatively low amounts of fibre, vitamins, and minerals. Their convenience, widespread availability, and intensive marketing may contribute to higher consumption, particularly among time-constrained and lower-income households, potentially widening existing health inequalities.

"For many Canadians, ultra-processed food is often a convenient and affordable option. But our findings suggest that diets high in these foods may be linked to brain changes that may lead to memory loss and stroke as Canadians grow older," said Anand.

In this study, ultra-processed foods made up an average of about 25 per cent of participants' daily food servings. For the heaviest consumers, that increased to 45 per cent of everything on their plates, compared with just 16 per cent for those who ate the least.

Researchers found that as the consumption of ultra-processed food increased, that of whole food decreased. Fruits, vegetables, grains and other minimally processed foods made up 41 per cent of daily servings among participants with the highest consumption of ultra-processed food, compared with 68 per cent among those with the lowest consumption.

“People who ate more ultra-processed foods weren’t simply eating more on top of their usual diet. These foods appeared to crowd out healthier whole foods,” added de Souza.

Researchers analyzed data from participants enrolled in two PHRI studies: the Canadian Alliance for Healthy Hearts and Minds and the Prospective Urban and Rural Epidemiology-MIND study. They completed detailed dietary questionnaires and underwent MRI brain scans reviewed by neurologists who were unaware of the participants’ dietary patterns.

The findings suggest a link between ultra-processed food consumption and signs of brain changes. However, because participants were only assessed once and weren’t followed over time, researchers couldn’t determine whether ultra-processed foods directly caused these changes.

“We need longer-term studies that track people over time with repeated MRI scans to find out whether reducing ultra-processed food intake can slow or prevent these brain changes,” said de Souza. “Such follow-up is ongoing.”

Physical activity may improve mood and quality of life during menopause

 

Published in Menopause Journal, the review of more than 1,000 women studied the effects of physical activity on psychological wellbeing and quality of life during perimenopause and early post menopause.  

Menopause is when a woman’s periods stop due to lower hormone levels. This usually happens between the ages of 45 and 55. It is estimated that there are currently around 13 million perimenopausal or menopausal women in the UK. 

Many women experience psychological symptoms during menopause, including depression, low mood, anxiety, stress, and difficulties with thinking and memory. These can have a significant impact on their quality of life, with an estimated one in ten women leaving work due to menopause symptoms. 

The study found physical activity, such as walking, dance and yoga, may help improve some of these psychological symptoms and overall quality of life during this period.  

As part of a systematic review and meta-analysis, researchers assessed 12 randomised controlled trials involving more than 1,000 women to determine how different types of physical activity impacted psychological symptoms during menopause. 

Types of physical activity were broken into two categories: aerobic-based exercise (ABIs), which included walking, Zumba, aerobic exercise, dance and Taekwondo, and mind-body activities (MBAs), which were made up of yoga, tai chi, Pilates and stretching. 

ABIs showed the strongest effects for reducing depressive symptoms and improving overall quality of life, with increased endorphin release linked to mood enhancement. This may be particularly relevant during perimenopause, when oestrogen fluctuations increase vulnerability to mood instability. 

ABIs also tended to involve fewer sessions, suggesting they may be easier to fit into for midlife women facing time and energy constraints. In one trial, women were instructed to walk three times per week for 30 minutes, and in another they attended three one-hour long Zumba classes per week. Across the 12 randomised trials, participants were required to attend multiple sessions per week, depending on the kind of physical exercise.  

In contrast, those who participated in MBAs saw strong improvements in psychological quality of life. These kinds of exercises incorporate mindfulness, breathwork and body awareness, which may enhance emotional regulation. In one trial, women attended two weekly 75 minute yoga sessions, while another trial saw participants attend daily one hour yoga classes. 

The researchers hope their findings will highlight how physical activity offers a low-cost and widely available intervention option for women experiencing psychological symptoms during menopause, compared to other intervention methods such as hormone therapy and cognitive behavioural therapy.  

The team also believe that the social aspect of physical activity, such as participating in group fitness classes, may have added to improved mood and quality of life. 

Senior author and Director of the UCL Menopause Mind Lab Professor Aimee Spector (UCL Division of Psychology and Language Sciences) said: “Physical activity is an effective, accessible, non-pharmacological strategy to support psychological well-being and quality of life during midlife menopause. 

“The majority of the interventions also used group-based formats, likely to foster social connection and peer support, both being factors associated with improved quality of life during menopause.” 

Improvements in depression, mood and quality of life were particularly evident among women in early post menopause (the stage of life that begins 12 consecutive months after a woman's final menstrual period), while physical activity was also associated with improvements in depressive symptoms during perimenopause. 

Lead author and NHS Clinical Psychologist Simone Saidel, who was a researcher at UCL when this review was conducted, said: “Treatment options for menopause are limited, with many women being unable to or choosing not to take hormone therapy. There are also significant health inequalities in terms of HRT access, and ethnic variations in attitudes towards it.  

“This study plays an important role in expanding the options available for symptom management, whereby clinicians may recommend it as an early intervention or an adjunct to medical or psychological treatments.” 

Further research is needed to establish which forms of physical activity are most beneficial and how they can best be incorporated into support and care for women experiencing menopause. 

Data was included from seven countries (Brazil, China, Tunisia, India, Iran, Korea and USA) to complete this review.  

Study limitations 

The researchers note that the evidence base remains limited, with substantial variation between studies and many of the studies judged to be at high risk of bias, highlighting the need for further high-quality trials. 

Frequent and unintentional daytime napping linked to higher dementia risk in older adults

 

Study of nearly 1,000 older Americans finds napping habits, not just nighttime sleep, may signal or contribute to dementia risk

Peer-Reviewed Publication

Johns Hopkins Bloomberg School of Public Health

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Daytime napping is common among older adults. New research from the Johns Hopkins Bloomberg School of Public Health suggests that how often, how intentionally, and how long older people nap may be linked to their risk of developing dementia.

The study, published online October 5 in The Journal of Gerontology: Medical Sciences, followed 995 U.S. Medicare beneficiaries age 65 and older who were free of dementia at the start of the study in 2013 and tracked them for up to 10 years using data from the National Health and Aging Trends Study, a nationally representative survey of older adults.

The researchers found that participants who napped frequently—defined as most days or every day—had a 48% higher risk of developing dementia compared to those who rarely or never napped, even after accounting for demographic factors, health conditions, and nighttime sleep characteristics such as sleep duration, daytime sleepiness, and a measure of obstructive sleep apnea risk. 

Unintentional napping—defined as falling asleep without meaning to rather than planning a nap—was associated with a 39% higher risk of dementia. Napping for 30 minutes or less was also linked to a 40% higher risk, an association that held up after accounting for a range of potential confounders, while the association for naps longer than 30 minutes weakened once nighttime sleep factors were considered.

“More frequent napping could be a marker of changes in the brain, rather than a cause of brain changes that lead to dementia,” says Adam Spira, PhD, MA, senior author of the paper and professor in the Bloomberg School’s Department of Mental Health.

The researchers point to the likely two-way relationship between napping and dementia. Napping is a potential risk factor for dementia at the same time that degenerating brain regions that help to regulate wakefulness—which can occur early during dementia—may also lead to more frequent napping.

To help address this possibility, the team excluded dementia cases diagnosed within the first five years of follow-up and found that the associations for frequent and unintentional napping remained similar, lending support to the idea that napping patterns may meaningfully precede a dementia diagnosis rather than simply reflect it.

“Monitoring napping behaviors could serve as an early and accessible marker to help identify older adults at higher risk for dementia and guide targeted interventions for dementia prevention,” says Kening Jiang, PhD, a postdoctoral fellow in the Bloomberg School’s Department of Mental Health and first author of the paper. 

Past research investigating the relationship between napping and cognitive decline has yielded mixed results, with some studies linking longer or more frequent naps to greater dementia risk and others finding no association or even potential benefits from short naps. The researchers note that differences in study design—including whether napping was self-reported or measured with wearable devices—and cultural attitudes toward napping across regions may help explain these inconsistent findings.

The researchers caution that the findings are observational and cannot establish that napping causes dementia. The study relied on self-reported napping habits, which can be subject to recall bias, and dementia status was determined using a validated algorithmic classification rather than clinical diagnosis. 

The researchers say that longer-term studies that combine detailed, objective measures of both daytime napping and nighttime sleep are needed to clarify how napping patterns relate to dementia risk and to determine whether changing napping habits could help delay or prevent dementia onset.

“Napping Characteristics and Incident Dementia: Results From the National Health and Aging Trends Study” was written by Kening Jiang, Alden L. Gross, Catriona Tingsea Wu, Junxin Li, Halima Amjad, Emerson M. Wickwire, Jennifer S. Albrecht, Atul Malhotra, Chien-Yu (Irene) Tseng, Marc Kaizi-Lutu, Chunyu Liu, Christopher N. Kaufmann, and Adam P. Spira.

Nature shown to ease loneliness

 

Global study suggests 'nature-based social prescriptions' could be an antidote to loneliness epidemic

Peer-Reviewed Publication

University of Colorado at Boulder

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University of Colorado Boulder Professor Jill Litt at a Horsebarn Garden in Denver Colorado. Credit: Jill Litt/CU Boulder

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Credit: Louissé Studio

About one in three Americans and one in six people worldwide feel lonely on a regular basis, a troubling reality that has prompted some public health officials to declare an “epidemic of loneliness.”

A new global study presents a novel remedy. It found that nature-based social prescribing — clinicians literally prescribing things like gardening, hiking or birdwatching — can significantly reduce loneliness. Spending time in nature with others works even better, particularly for the loneliest among us, the study found. 

“There has been a lot of passion about nature-based prescriptions, but not a lot of evidence,” said corresponding author Jill Litt, professor of environmental health at CU Boulder and principal investigator for the RECETAS project, which has studied a social prescribing model called Friends in Nature in 1,200 adults in six cities across Europe, Latin America and Australia.

Thus far, all the trials have shown promising results. The latest findings, looking at 320 lonely adults in Barcelona, appear in the October issue of the journal Lancet Regional Health.

“We now have randomized controlled trials showing this works and the impacts last,” said Litt.

What is loneliness?

As Litt explains, loneliness is not about being physically isolated. Rather, it is a “subjective disconnect between one’s expectations of their social relationships and one’s reality.”

“I’ve heard people describe it like a knot in their stomach, like something is just not right,” said Litt. “You could be in a room full of people and still feel lonely.” 

Studies show that chronic loneliness can increase risk of cardiovascular disease, dementia, stroke, depression and anxiety. It can also burden the healthcare system, as people suffering from loneliness tend to visit their doctor more and are more likely to visit the emergency department with vague complaints on Friday afternoons — a phenomenon known as “Friday afternoon syndrome.” 

Due to stigma, people are often reluctant to admit or don’t recognize they are lonely and assume the physical symptoms they feel are due to something else.

“Once clinicians really start to drill down to the root causes, they discover that loneliness is a big factor and the solutions may lie outside the traditional medical system,” said Litt, who is also a researcher with the Barcelona Institute for Global Health.

Nature as medicine

RECETAS (Re-imagining Environments for Connection and Engagement) was launched in 2021 with a $5.6 million grant from the European Union. It has since conducted randomized controlled trials in Barcelona, Spain; Prague, Czech Republic; and Helsinki, Finland; and quasi-experimental studies in Marseille, France; Cuenca, Ecuador; and Melbourne, Australia.

The newest findings center around the site in Barcelona

The study included 320 lonely older adults from 12 low-income neighborhoods. Half were placed in a group of 8–10, which spent two hours weekly for nine weeks together doing things like gardening, birdwatching or nature-based art programs along with two trained facilitators. The other half were provided the same menu of free, easily accessible nature-based activities that they could do on their own. Both strategies worked. Participants on average showed an 11% reduction in loneliness scores at three months; 12% at six months; and 17% at one year. For those who started with lower emotional wellbeing, the group intervention worked better.

Litt said that nature, with its vivid sounds, smells and sights, can act as an “additional facilitator,” augmenting therapeutic benefits.  

Even being in nature alone can alleviate loneliness, the research suggests.

“Being out in nature forms this kind of reservoir of calm that we can return to later in life during stressful times,” said Louise Chawla, an environmental psychologist and professor emerita at CU Boulder who recently coauthored another paper with Litt about the role that nature can play in fostering social connections. “It’s not just restorative when you are in a place but also when you go back to it in memory.”

Public health agencies in Spain have already begun to recognize the Friends in Nature model as a best-practice for addressing the loneliness epidemic. Litt is now working to bring similar trials to the U.S. in hopes that someday, insurers might cover things like a membership in a community garden or birdwatching club.

“We have nature in our cities and investment in our green infrastructure,” she said. “Now we need a mechanism to bridge these resources with our health systems to offer person-centered care that leverages the power of nature for healing and wellbeing.”

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DOI

10.1016/j.lanepe.2026.101821

A handful of walnuts a day may make your diet less inflammatory

 

A new study from Loma Linda University School of Public Health, published in the Journal of the Academy of Nutrition and Dietetics, suggests that regularly incorporating walnuts into the diet may shift the overall diet pattern toward lower inflammatory potential.

The Dietary Inflammatory Index (DII) is a research tool that estimates whether a person's overall diet has characteristics associated with higher or lower inflammatory potential based on the foods and nutrients they consume.

The study, “The Dietary Inflammatory Index is Lower Among Healthy Older Adults Consuming a Walnut-Supplemented Diet. Ancillary Results from the Walnuts and Healthy Aging Randomized Controlled Trial,” found that older adults who consumed 1-2 oz of walnuts (30-60 g) of walnuts daily had slightly but statistically significantly lower DII scores than those in the control group. 

The findings suggest that incorporating walnuts into the diet may shift the overall dietary patterns toward lower inflammatory potential.  These findings add to previous results from the Walnuts and Healthy Aging Studyshowing that daily walnut consumption was associated with reductions in several circulating markers of inflammation. Together, the findings suggest that incorporating walnuts into the diet may influence both the inflammatory potential of the overall diet and biological markers of inflammation.

This latest report builds on data from more than 20 research papers published as part of the Walnuts and Healthy Aging Study, a major two-year clinical trial conducted by researchers at Loma Linda University School of Public Health and Hospital Clinic of Barcelona in Spain. The two teams have focused on investigating the effects of daily walnut consumption on older adults. The study was supported by a grant from the California Walnut Commission.

This most recent study followed 319 older adults from Loma Linda, California, for two years. Half were assigned to consume 1-2 ounces of walnuts daily, while the remaining control group participants abstained from walnuts while significantly limiting their consumption of other nuts. Neither group was instructed to make any additional dietary changes. Participants met with researchers five times during the two-year study and provided reports of the food and beverages they had consumed during the previous 24 hours.

At the end of two years, participants who consumed walnuts had slightly but statistically significantly lower DII scores than those in the control group. 

Sujatha Rajaram, PhD, professor in the School of Public Health, served as the study’s senior investigator. "The important message is that incorporating nutrient-rich food such as walnuts is a simple and practical step towards shifting your dietary pattern to be less inflammatory," Rajaram said. "This illustrates how a relatively simple food choice can contribute to the overall diet quality."

“The important message is that incorporating walnuts into the diet was associated with a shift toward a less inflammatory dietary pattern,” Rajaram said. “This illustrates how a relatively simple food choice can contribute to the overall quality of the diet.”

Read the full story here.

 

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Journal

Journal of the Academy of Nutrition and Dietetics

DOI

10.1016/j.jand.2026.156835 

Healthy diet during pregnancy associated with reduced risk of infant colic, eczema

Key points:

• Infants born to mothers who ate a healthy, Mediterranean-style diet during pregnancy were at significantly lower risk for colic and eczema, while those born to mothers who ate a less healthy, more inflammatory diet were at higher risk.

• For each weekly serving of seafood a pregnant woman consumed, her infant had a 25% lower chance of having colic and eczema.

• The study is the first to examine how prenatal diet influences infant colic and eczema, which prior studies by the researchers linked to higher risk of developing allergic conditions, such as asthma and food allergies, later in life.

Boston, MA—Infants born to mothers who ate a healthy, Mediterranean-style diet during pregnancy were at lower risk for colic and eczema, according to a new study by researchers at Harvard T.H. Chan School of Public Health, Boston Children’s Hospital, and Harvard Pilgrim Health Care Institute. The researchers also found that regularly consuming seafood during pregnancy helped lower an infant’s risk for these conditions.

“Our own prior studies have shown that babies who had colic have higher rates of atopic conditions in later life, including asthma, seasonal rhinitis and food allergies,” said corresponding author Jenifer Lightdale, associate chief of the Division of Gastroenterology, Hepatology and Nutrition at Boston Children’s Hospital and professor of pediatrics at Harvard Medical School. “Our new study is the first to ask how prenatal diet may influence colic, and in particular the combination of colic and eczema, as babies who have both conditions in infancy may be at highest risk for various manifestations of allergies when they are older.”

The study will be published Oct. 12 in JAMA Network Open.

Previous research on diet and colic has focused on whether dietary changes after birth in breastfeeding mothers, or in choices of infant formulas, can affect the symptoms of colic once they are present. For this study, the researchers examined whether the dietary habits of women during pregnancy would be associated with the risk of colic in her baby, particularly the combination of colic and eczema.

More than 1,300 pregnant women were recruited into the Project Viva study from prenatal clinics in Eastern Massachusetts from April 1999 to November 2002. The participants filled out regular food questionnaires, which the researchers scored according to the Mediterranean Diet Score (MDS) and the Dietary Inflammation Index (DII). A high MDS score indicated a more healthful diet, with high intake of fruits, vegetables, whole grains, legumes, and healthy fats, and moderate intake of dairy and lean proteins. A high DII score indicated a less healthful diet, with high intake of red or processed meats, sugar-sweetened beverages, sodium, and refined grains. Participants also reported their intake of commonly allergenic foods, including peanuts, peanut butter, and other nuts; finfish and shellfish; and eggs and dairy.

The researchers found that 26% of the study’s infants had colic, and 5% had both colic and eczema. Mothers who adhered more closely to a Mediterranean diet had a significantly lower risk of having a baby with both colic and eczema: Each higher MDS point was associated with a 15% reduction in risk. By contrast, each higher DII point was associated with a 34% higher risk.

Looking at foods known to be common allergens, the researchers found that for each weekly serving of seafood a pregnant woman consumed, her infant had a 25% lower chance of having colic and eczema. Other typical allergenic foods—including dairy, eggs, and nuts—were not related to having a baby with colic and eczema. The researchers calculated that all of the associations the study found were strongest among infants whose mothers had a history of allergic conditions.

“Our findings provide yet another reason to help pregnant women achieve a healthy, balanced diet, with a particular emphasis on eating seafood,” said first author Emily Oken, president of the Harvard Pilgrim Health Care Institute and professor in the Department of Nutrition at Harvard Chan School. “Moms wish to do all they can for their babies, but there are often financial and other structural barriers to accessing healthy nutrition. We hope our study can be helpful not just to individuals and families, but also to programs and services that support women’s health and nutrition, including federal programs like WIC and SNAP as well as programs administered by health plans and systems, such as ‘food is medicine’ initiatives.”

Article information

“Maternal Prenatal Diet and Colic and Eczema Among Infants,” Emily Oken, Sheryl L. Rifas-Shiman, Karen M. Switkowski, Kari Nadeau, Jenifer R. Lightdale, JAMA Network Open, October 12, 2026, doi: 10.1001/jamanetworkopen.2026.38472

Cannabis does not help you sleep better

 

• Study followed adults for 35 years, from young adulthood into middle age
• Long-term cannabis use linked to lower sleep quality measured by wrist-worn monitors
• Findings suggest cannabis-related sleep disruptions may go unnoticed by users themselves
• Sleep medicine expert offers well-established strategies that can improve sleep quality

Millions of Americans use cannabis products as sleep aids, but a new Northwestern Medicine study suggests marijuana may not improve sleep the way many people believe it does. 

The study found both lifetime and recent cannabis use were associated with poorer objectively measured sleep quality, even though participants generally did not perceive their sleep to be worse. 

The scientists followed participants from young adulthood into middle age for nearly 35 years, repeatedly tracking their cannabis use over time. In middle age, participants wore a wrist-based sleep monitor for a week and completed sleep surveys, allowing the scientists to compare objective measures of sleep with participants' own perceptions of how well they slept.

The study found both long-term and recent cannabis use were associated with poorer sleep quality when the wrist-worn monitoring device objectively measured participants’ sleep. However, participants who used cannabis generally did not report sleeping worse than people who didn't use it. The findings suggest cannabis-related sleep disruptions may go unnoticed by users themselves, the study authors said. 

The study was published today (Oct. 9) in JAMA Network Open. 

“This study challenges the common belief that cannabis helps people sleep better,” said corresponding author Dr. Thanh-Huyen T. Vu, research associate professor of preventive medicine (epidemiology) at Northwestern University Feinberg School of Medicine. “Our findings suggest cannabis may actually be associated with poorer sleep quality, even if people don't perceive those changes.” 

While the study was not designed to determine whether cannabis directly causes sleep problems, it provides some of the strongest evidence to date that long-term recreational cannabis use and better sleep quality may not be as closely aligned as commonly believed.

“Our data do not support the belief that cannabis is helpful as a sleep aid,” said senior author Mercedes R. Carnethon, chair of the department of preventive medicine at Feinberg. “As cannabis becomes increasingly available and accepted, it's important to better understand its long-term associations with health behaviors such as sleep.”

A breakdown of the study findings

The study analyzed data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a long-running, community-based study that began in 1985-86 and follows Black and white adults across the U.S. 

Among 1,266 participants, the study found greater lifetime cannabis exposure was associated with poorer objective sleep quality. People with higher cumulative cannabis use spent a lower percentage of the night asleep, experienced more fragmented sleep and spent more time awake after initially falling asleep.

Recent cannabis users showed similar patterns. Compared with people who never used cannabis, recent users were more likely to have lower sleep efficiency, greater sleep fragmentation and longer periods of wakefulness during the night. They also were significantly more likely to sleep longer than eight hours per night, the study found. 

When researchers asked study participants to rate their own sleep quality, however, cannabis use showed no association with whether people felt they slept well or poorly.

“This was one of the most interesting findings,” Vu said. “The wearable device detected more nighttime disruption among participants with long-term cannabis exposure, but the participants themselves generally did not report worse sleep.”

After adjusting for numerous factors known to affect sleep — age, sex, race, cigarette smoking, alcohol use, physical activity, depression, chronic health conditions and use of other substances — cannabis use remained associated with poorer objectively measured sleep, the study found. 

The researchers did not distinguish between modes of cannabis consumption (e.g., smoking versus consuming edibles). Given that the participants were followed over several decades, patterns of cannabis use likely changed over time, which the study authors said makes this an especially important question for future studies.

Better ways to support healthy sleep

While cannabis may not be the sleep solution many people believe it is, there are well-established strategies that can improve sleep quality, said study co-author Kristen L. Knutson, associate professor of neurology (sleep medicine) and preventive medicine (epidemiology) at Feinberg.

“Keep a regular bedtime, make your bedroom cool, dark and quiet, and avoid looking at phones and other screens right before bed,” Knutson said. “It can also help to establish a calming routine before sleep, such as reading, meditating or taking a shower. If sleep problems persist, or if you're a loud snorer, talk with your health care provider to rule out an underlying sleep disorder.”

The study is titled, “Recent and Cumulative Cannabis Use and Sleep in Middle-Aged Adults.”

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Journal

JAMA Network Open

DOI

10.1001/jamanetworkopen.2026.38303