NewsMakers
Spending more than 3 hours a day sedentary worsens teens’ mental health
Adolescents who spend more than three hours a day engaged in sedentary behaviors – including playing video games, reading for leisure or spending a lot of time distracted by screens – have a higher risk of facing psychological distress in the future.
Adolescents who spend more than three hours a day engaged in sedentary behaviors – including playing video games, reading for leisure or spending a lot of time distracted by screens – have a higher risk of facing psychological distress in the future, according to a study published in the Journal of Adolescent Health.
On the other hand, moderate screen exposure (between 60 and 119 minutes per day) invested in educational activities, such as doing homework or attending classes, was considered a “protective” factor associated with less psychological distress.
Sedentary behavior among adolescents has become a growing problem worldwide, with significant implications for the physical and mental health of the population in this age group. Several studies have shown that a lack of physical activity, especially when combined with excessive use of electronic devices, contributes to an increase in problems such as obesity and cardiovascular disease.
In addition, a growing body of research shows that the effects of a sedentary lifestyle are not limited to the physical body, but can also affect mental health, increasing feelings of anxiety and depression, for example.
The study, conducted at the Institute of Psychiatry, Psychology and Neuroscience at King’s College London in the United Kingdom, analyzed information from 3,675 adolescents who were part of the Millennium Cohort Study, a project that follows children born between 2000 and 2002 and maintains a large database.
The analysis included information on sedentary behavior collected at two points in time: when the adolescents were 14 years old and then at the age of 17. In the first phase, the participants completed a diary in which they recorded the different activities they performed every ten minutes. These activities were categorized into broader contexts: general physical activity, time spent sleeping, recreational screen time, non-screen recreational time, and educational sedentary behavior.
At age 17, the same participants reported their psychological distress using a six-question questionnaire about their feelings, using a tool known as the Kessler Scale. The questions included “how often in the past 30 days” did the participant feel nervous, hopeless, restless, depressed, anxious, and worthless. Analysis of the scores, based on the scale, indicated whether or not they were in psychological distress.
According to André de Oliveira Werneck, author of the article and doctoral student at the Center for Epidemiological Research in Nutrition and Health at the School of Public Health of the University of São Paulo (FSP-USP) in Brazil, the fact that the research was based on responses to sedentary behavior recorded in a diary is one of the differences that make the results so relevant.
Werneck explains that there are several ways to measure sedentary behavior. One of them, which is more objective, uses an accelerometer (a type of device that measures how much a person moves), but it cannot distinguish between different sedentary activities, which are very broad.
“Sedentary behavior includes a variety of activities, such as using a computer, watching television, reading, listening to music, or attending class. Most research focuses on analyzing total sitting time, but we can have positive sedentary activities, such as attending class and doing homework, for example. And there are activities that are not beneficial, such as spending too much time on the Internet or playing video games,” he explains.
A second method of measuring sedentary behavior is subjective, in which people answer a questionnaire about how much time they spend sedentary, watching TV, playing video games, working, or studying in a typical week. Nevertheless, it depends on the participant’s memory.
“Having a record of all the activities of these adolescents, formalized in a diary, provides a much more faithful result and has a more reliable accuracy of the different time periods. It’s not common to use this type of tool, precisely because it’s difficult to implement,” says the doctoral student, who carried out the study as part of a research internship funded by FAPESP.
Impact of reading
To analyze the data, the researchers adjusted for several covariates, including gender, parental education, net family income, parental psychological distress, body mass index, physical activity, total sedentary time and depressive symptoms.
After cross-checking the information, they found that the adolescents spent an average of four hours a day in educational sedentary behavior (school, homework) and about three hours a day in screen and non-screen sedentary behavior. Those who spent more than 180 minutes a day on screens for leisure were associated with greater psychological distress at age 17.
Similarly – and surprisingly – the researchers found that those who spent more than three hours a day reading for leisure (especially boys) also reported more psychological distress. According to the study, while previous research has shown that reading is associated with better mental health outcomes and other healthy behaviors, this new research suggests that excessive reading may be harmful in some cases.
One of the hypotheses to explain this finding, says Werneck, is that adolescents who spend many hours reading are “displacing” time that could be spent on activities with face-to-face or outdoor social interactions, which are protective, leading to greater isolation. In addition, it is possible that some of the reading is done on screen devices (cell phones, computers or tablets), which is also harmful – there are studies in adults that link screen reading to poorer sleep because of exposure to blue light.
“This is an unexpected finding in the study, but it’s important to emphasize that very few adolescents spend a lot of time reading for leisure. Our main finding, given the general context, is that more leisure screen time [video games] was associated with worse psychological distress, while more time in educational activities was associated with less distress,” he says.
Professor Brendon Stubbs, who supervised the study, told Agência FAPESP by email that the study revealed several worrying patterns. “We found that adolescents who spent more than three hours a day on screen-based leisure activities showed significantly greater psychological distress three years later. Video games were particularly influential, with each additional hour associated with a 3% increase in psychological distress.”
According to Stubbs, the results suggest a clear dose-response relationship between excessive recreational screen time and future mental health outcomes. “Importantly, this relationship was context-dependent, meaning that educational screen time did not show the same negative effects, highlighting that the problem is not screen use per se, but how and why screens are used.”
How to minimize the impact
Based on the findings, the researchers suggest interventions that could help minimize the negative psychological effects:
- Set clear limits on screen time: Implement guidelines that limit recreational screen time to less than three hours per day, as the study results show that this is when the risks increase significantly;
- Focus on context: Encourage more educational and structured screen activities rather than passive recreational screen time. The study found that educational screen time had no negative effects;
- Balance activities: Promote alternative leisure activities with social interaction components, as isolated screen time can contribute to psychological distress;
- Gender-specific approaches: Consider personalized interventions, as work has found gender differences in effects (e.g., girls were more associated with screen use for Internet browsing, boys for video games);
- Educational support: Since moderate amounts of homework and class time have been associated with less psychological distress, ensure adequate academic engagement;
- Manage and optimize screen time instead of eliminating it altogether.
Werneck emphasizes that sedentary behavior is very complex, and for adolescents, each activity and context needs to be evaluated separately. “We need to focus on interventions that not only reduce sedentary behavior but also reduce it in some specific and very long activities that are more associated with psychological distress,” he concludes.
NewsMakers
Could your oral health be affecting fertility?
Chronic oral inflammation may impair female fertility by triggering a systemic immune response that affects the ovaries. A new study shows this leads to oxidative damage, reduced egg quality, disrupted follicle development and reduced live birth rate. These findings point to a potential biological link between oral health and unexplained infertility, opening new directions for future treatments.
A new study led by Prof. Michael Klutstein at the Hebrew University of Jerusalem and Prof. Asaf Wilensky at the Hebrew University-Hadassah Medical center and spearheaded by the students Dr. Paz Kles and Stephen Ameho has uncovered a striking biological link between chronic oral inflammation and female fertility, suggesting that conditions in the mouth may have far-reaching effects on reproductive health.
Published in the Journal of Dental Research, the study shows that persistent inflammation in the oral cavity can impair ovarian function, reduce egg quality, and ultimately lower fertility rates.
Researchers examined in a mouse model inflammation associated with dental implants, a common clinical scenario, and tracked how immune signals spread throughout the body. Their findings reveal that inflammation does not remain confined to the oral cavity but triggers a systemic immune response that reaches the ovaries.
The consequences were significant. Chronic oral inflammation in the animals was linked to increased levels of inflammatory cytokines in the ovaries, along with shifts in immune cell populations. This was accompanied by oxidative damage to ovarian tissue, impaired development of follicles, and reduced quality of oocytes.
These biological changes translated into measurable reproductive outcomes, with markedly reduced birth rates observed under inflammatory conditions in the animals.
The study also identified deeper cellular effects. Oocytes exhibited DNA damage and epigenetic alterations resembling those seen in reproductive aging, pointing to a possible mechanism by which inflammation accelerates the decline in fertility.
“Inflammation is often thought of as a localized response, but our findings show that it can have systemic consequences that extend as far as the reproductive system,” said Prof. Michael Klutstein. “This work suggests that chronic oral inflammation may be an underrecognized factor in female infertility, potentially contributing to cases that currently have no clear explanation.”
The findings add to growing evidence that oral health is closely linked to overall health. Chronic oral inflammatory conditions such as periodontitis are widespread and have already been associated with a range of systemic diseases.
The researchers note that further investigation in clinical settings will be essential to determine how these findings translate to patient care. If confirmed, the work could open new avenues for diagnosis and treatment, including the use of anti-inflammatory or antioxidant approaches to improve fertility outcomes.
NewsMakers
Maintaining a healthy heart may require regular doses of positivity
The findings of this study further point to the importance of attending to mental and behavioral health for cardiovascular disease prevention and cardiovascular health optimization.
Positive psychology interventions such as mindfulness, gratitude journaling and optimism training can consistently improve blood pressure, inflammation markers and other cardiovascular disease risk factors within a matter of weeks, a recent study found. However, since these benefits are associated with lifestyle changes such as eating healthier and greater physical activity, the researchers suggested that ongoing reinforcements may be needed to stay on course long term.
Rosalba (Rose) Hernandez, a professor of social work at the University of Illinois Urbana-Champaign, led a team that analyzed the findings of 18 randomized controlled trials that used positive psychological and mindfulness interventions to enhance mental or physical health.
The programs that the team reviewed included individual methods — such as structured telephone sessions, journaling with brief check-ins and digital platforms such as apps and text messaging — and interactive in-person group sessions, as well as hybrid formats that blended these with online tools and virtual meetings. Most of the programs consisted of weekly sessions and at-home activities that reinforced the skills taught, with the majority of programs lasting from six to 12 weeks, the team found.
In general, the programs included 50-200 adults with elevated cardiovascular risk factors such as uncontrolled hypertension, heart failure or other conditions. Typically, the participants were in their late 50s to mid-60s, and women comprised 35-55% of the samples across those studies that reported their participants’ gender, according to the researchers.
“In hypertension and postacute coronary syndrome cohorts, mindfulness-based programs delivered over an eight-week period reduced systolic blood pressure and lowered inflammatory markers such as high-sensitivity C-reactive protein and fibrinogen,” said Hernandez, who is a Fellow of the American Heart Association. “A 12-week spirituality-based digital intervention achieved one of the largest reductions — reducing systolic blood pressure measured with a standard cuff by 7.6 points, and central systolic pressure — which is measured in the aorta as it leaves the heart — by 4.1 points.”
In prior research on positive psychology interventions, scientists seldom defined the dose that was needed to obtain the beneficial effects, Hernandez said. She and the team members sought to clarify the frequency and duration that was most likely to improve individuals’ cardiovascular health.
Programs that had more frequent contact with their participants yielded the most consistent physiological benefits, underscoring the opportunity to embed positive psychological strategies into long-term cardiovascular care, Hernandez said.
The team found that the strongest behavioral improvements were achieved by an eight-week program delivered over WhatsApp that combined weekly sessions with daily microtasks, motivating participants to engage in greater physical activity, eat a healthier diet and take their medication as prescribed. A program that included motivational interviewing succeeded in increasing cardiac patients’ levels of physical activity by 1,800 steps a day and their medication adherence, while the mindfulness programs improved participants’ activity levels and diets only, according to the study.
“The therapeutic dose that was most consistently linked with improvements in blood pressure, inflammation and endothelial function was daily practice reinforced by weekly sessions over eight to 12-week periods,” Hernandez said. “Therapeutic dosing typically involved high-frequency dosing over this time period to obtain short-term physiologic benefits, while ongoing less-intensive contact may be needed to sustain behavioral change.”
Published in the journal Cardiology Clinics, the study was co-written by University of South Florida social work professor Soonhyung Kwon; Alyssa M. Vela, a professor of surgery and of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine; and Katharine S. Edwards, a professor of cardiovascular medicine and of psychiatry and behavioral medicine at Stanford Medicine.
“The findings of this study further point to the importance of attending to mental and behavioral health for cardiovascular disease prevention and cardiovascular health optimization,” Vela said. “This speaks to the need for routine screening and integration of cardiac behavioral medicine to allow for access to important interventions.”
The current study adds to a growing body of research linking psychological well-being — including traits such as optimism, positive affect and gratitude — with cardioprotective benefits.
NewsMakers
Heart disease risk may start in the womb, study finds
Young adults whose mothers had high blood pressure during pregnancy — either pregnancy-associated hypertension, pre-eclampsia or eclampsia — had more signs of early arterial injury, higher blood pressure, higher body mass index and higher blood sugar than peers.
A child’s future heart health may be partially shaped before they are born, reports a new Northwestern Medicine study that found pregnancy complications are linked to poorer cardiovascular health in offspring more than 20 years later.
The study found that young adults whose mothers had high blood pressure during pregnancy — either pregnancy-associated hypertension, pre-eclampsia or eclampsia — had more signs of early arterial injury, higher blood pressure, higher body mass index and higher blood sugar than peers.
The authors said the study adds to growing evidence that cardiovascular risk may be transmitted across generations through a combination of biological, environmental and behavioral factors.
“That means we must make sure people maintain good health from childhood into young adulthood, so that if or when someone becomes a parent, they pass on the best opportunity for good health to their children,” said study senior author Dr. Nilay Shah, assistant professor of medicine in the division of cardiology at Northwestern University Feinberg School of Medicine.
How the study was conducted
Shah and colleagues evaluated nearly 1,350 mother-child pairs from the Future of Families and Child Well-Being Study, which enrolled mothers and children at birth between 1998 and 2000 across 20 U.S. cities. The children were then followed into adulthood.
Using delivery hospitalization records, the Northwestern scientists first identified whether mothers experienced pregnancy complications, including high blood pressure during pregnancy, gestational diabetes (high blood sugar during pregnancy) or preterm birth (before 37 weeks of pregnancy).
The three pregnancy complications are on the rise, and affect almost one in four pregnancies in the U.S.
The research team then analyzed cardiovascular health of offspring at age 22, using blood pressure measurements, blood testing, body mass index assessments and carotid artery ultrasounds to look for signs of artery injury.
Finally, the scientists compared participants with and without exposure to each pregnancy complication and adjusted for factors like income, education, difference in birth weight and smoking during pregnancy.
Key findings
At around age 22, participants whose mothers had high blood pressure during pregnancy had:
- Higher body mass index (+2.8 BMI points)
- Higher diastolic blood pressure (+2.3 mm Hg)
- Higher blood sugar levels (+0.2% HbA1c)
- Thicker artery walls (~0.02 mm)
While the difference in artery wall thickness may seem small, the study authors said it corresponds to roughly three to five years of additional vascular aging. That means arteries looked older and less healthy than expected, which raises the risk of future heart disease.
Other pregnancy complications also showed some long-term effect:
- Exposure to gestational diabetes was linked to worse blood pressure and some evidence of artery thickening
- Being born preterm was associated with higher blood sugar levels
‘Most heart disease is preventable’
With pregnancy complications on the rise in the U.S., Shah said the study provides compelling evidence that improving health before and during pregnancy could help reduce heart disease risk in the next generation.
“There is evidence that both parents’ health at the time of conception and during pregnancy influences a child’s health,” he said. “So, promoting health from an early age, like exercising regularly, eating healthfully, never smoking and getting enough sleep, is not just meant for an individual, but doing so may help future generations be healthier, too.”
Shah also emphasizes that risk is not destiny.
“The good news is that most heart disease is preventable,” he said. “If you experienced high blood pressure or high blood sugar during pregnancy, or your child was born early, it does not absolutely mean that your child will have worse health as adults. But I would encourage you to pay attention now to your child’s health behaviors.
“What children learn in childhood sets the stage for their health across their lives. If you are wondering whether your children’s behaviors are healthy, or are considering making a change, please speak with your child’s pediatrician for advice and guidance.”
Other Northwestern co-authors include Emily Lam, Abigail Gauen, Dr. Sadiya Khan, Alexa Freedman and Norrina Allen.
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