Keith M. Diaz

Insufficient sleep is associated with obesity. However, the causal effect on weight status of chronic, mildly insufficient sleep and its potential variability by gender and menopausal status remain unknown. To explore the effect of 6 weeks of sleep restriction (SR) of 1.5 hours per night on energy balance and body weight regulation. Pooled analysis of 2 randomized crossover trials. (ClinicalTrials.gov: NCT02960776 and NCT02835261). Outpatient intervention with inpatient and outpatient assessments. Adults (n = 95) aged 20 years or older at elevated cardiometabolic risk with habitual sleep of 7 or more hours per night. Six weeks of sustained adequate sleep (AS) and SR of 1.5 hours per night separated by a multiweek washout. Outcome measures included adiposity (assessed using magnetic resonance imaging), body weight, waist circumference, and energy balance behaviors and biomarkers. Sleep duration was reduced by 78.4 minutes (95% CI, -83.5 to -73.3 minutes) per night with SR versus AS. Body weight (0.45 kg [CI, 0.33 to 0.57 kg]), waist circumference (0.52 cm [CI, 0.25 to 0.79 cm]), and whole-body volume (0.56 L [CI, 0.19 to 0.93 L]) were increased with SR relative to AS. Leptin levels were elevated with SR versus AS (2.03 ng/mL [CI, 0.38 to 3.68 ng/mL]). Sedentary time was increased by 17.2 minutes (CI, 11.7 to 22.7 minutes) per day with SR versus AS. The intervention duration may have been too short to identify changes in body composition, power to evaluate individual differences was limited, and effect sizes were modest. Prolonged exposure to moderately short sleep may lead to weight gain, suggesting that weight management and cardiometabolic disease prevention programs should consider incorporating sleep strategies to promote AS. National Institutes of Health and American Heart Association.

Brief, regular movement breaks have been proposed as a public health strategy to offset the harms of prolonged sedentary behaviour; however, their real-world viability is unclear. This study aimed to assess the implementation potential, effectiveness on psychosocial outcomes and optimal dosing of movement breaks in naturalistic settings. Methods: Adults (n=19 342) enrolled in a 2-week pragmatic intervention embedded within an interactive podcast; of whom 59.4% (n=11 484) initiated the intervention. Participants took 5-minute walking breaks at their self-selected break frequency (three arms: every 30, 60 or 120 min). Implementation potential was assessed using the Feasibility, Acceptability and Appropriateness of Intervention Measures (FIM, AIM, IAM). Fatigue, positive affect and negative affect were assessed pre-intervention and post-intervention. Results: All arms exceeded the viability threshold (>3.0) for implementation outcomes. Feasibility was higher at lower break frequencies (FIM: 30 min=3.41, 60 min=3.80, 120 min=4.01), while acceptability and appropriateness were high across arms (AIM: 30 min=3.91, 60 min=4.03, 120 min=4.03; IAM: 30 min=4.00, 60 min=4.04, 120 min=3.99). Reported fatigue and negative affect decreased and reported positive affect increased significantly across all arms. Improvements showed a dose-response pattern: the 30-minute and 60-minute arms exceeded minimal important difference thresholds for fatigue (change: 30 min=−1.55, 60 min=−1.41, 120 min=−1.19) and positive affect (change: 30 min=1.86, 60 min=1.65, 120 min=1.27), with only the 30-minute arm exceeding the threshold for negative affect (change: 30 min=−1.00, 60 min=−0.92, 120 min=−0.67). Conclusion: In this large-scale, pragmatic intervention, movement breaks demonstrated good implementation potential and effectiveness for improving psychosocial outcomes over the 2-week intervention period. Hourly breaks offered the best balance between feasibility and effectiveness. These findings support movement breaks as a potentially viable public health strategy to reduce the harms of prolonged sedentary behaviour.

Elevated posttraumatic stress symptoms (PSS) impact ∼13% of coronary artery disease patients after acute cardiac events and may increase the risk of recurrent events through elevated heart rate (HR), driven by high sympathetic nervous system activity. We investigated whether PSS assessed with the Posttraumatic Stress Disorder Checklist for the Diagnostic and Statistical Manual of Mental Disorders-5 (PCL-5) are associated with elevated ambulatory HR in recently discharged cardiac patients, independent of PSS-linked health behaviors. Participants (N = 116; 34.4% women, 74% Hispanic, M_age = 61 years) with elevated (PCL-5 ≥ 20, n = 42) or nonelevated (PCL-5 ≤ 5, n = 74) PSS wore 24-hr electrocardiography monitors and wrist actigraphy for 2 weeks, with beta-blocker adherence electronically tracked. Although the elevated PSS group's mean HR was not significantly higher (3.50 beats per minute, p = .10), each 10-point increase in continuous PSS was significantly associated with 1.6 beats per minute higher HR, p = .009. This effect remained after adjusting for diurnal HR variation, age, sex, cardiac risk score, medical comorbidities, and three objectively estimated, PSS-linked health behaviors relevant to HR-physical activity, sleep episode length, and beta-blocker adherence. Findings suggest the potential value of targeting postcardiac event PSS to mitigate chronic sympathetic arousal. The use of intensive monitoring and high-resolution behavioral data strengthens the evidence for a physiological pathway linking psychological distress to elevated HR in cardiac patients. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

BACKGROUND: Patients hospitalized with symptoms of acute coronary syndrome remain at high risk for adverse events postdischarge, highlighting a need for modifiable therapeutic targets. The role of sedentary behavior in this risk and the potential benefits of replacing sedentary time with other activities remain unclear. This study examined the association between sedentary behavior and 1-year cardiac events/mortality among patients evaluated for acute coronary syndrome and estimated risk reductions from substituting alternative activities for sedentary time. METHODS: Patients presenting to the emergency department of a New York City hospital with acute coronary syndrome symptoms were enrolled from 2016 to 2020. Sedentary behavior, light-intensity physical activity, moderate-to-vigorous physical activity, and sleep were measured via a wrist-mounted accelerometer worn for 30 days postdischarge. Cardiac events and all-cause mortality were ascertained 1 year postdischarge via participant contact, electronic health records, and the Social Security Death Index. Participants were categorized into tertiles of sedentary time, with tertile 1 representing the lowest sedentary time and tertile 3 the highest. Cox proportional hazards regression models were used to evaluate associations. RESULTS: Of 609 participants (mean age, 62 years; 52% male, 58% Hispanic), 8.2% experienced a cardiac event or died within 1 year. Mean sedentary time was 13.6 h/d (SD, 1.8). Sedentary time was associated with increased risk of cardiac events/mortality (tertile 2: hazard ratio [HR], 0.95 [95% CI, 0.37–2.40]; tertile 3: HR, 2.58 [95% CI, 1.11–6.03]; P _trend =0.011). In isotemporal substitution analyses, replacing 30 minutes of sedentary time (referent) with sleep (HR, 0.86 [95% CI, 0.78–0.95]), light-intensity physical activity (HR, 0.49 [95% CI, 0.32–0.75]), or moderate-to-vigorous physical activity (HR, 0.39 [95% CI, 0.16–0.96]) was associated with lower cardiac event/mortality risk. CONCLUSIONS: Sedentary behavior was associated with increased risk of 1-year cardiac events/mortality among patients evaluated for acute coronary syndrome. Replacing sedentary behavior with sleep, light-intensity physical activity, or moderate-to-vigorous physical activity was associated with lower risk. These findings highlight reducing sedentary behavior as a potential strategy to improve posthospitalization outcomes.

Excessive sedentary behavior is highly prevalent in developed nations and is a risk factor for cardiovascular disease (CVD) morbidity and mortality. As such, health agencies have provided general recommendations to “sit less, move more” by interspersing brief periods of activity. However, a lack of empirical evidence describing how often (e.g. every 30 min, every 60 min) and for how long (e.g., 1 min activity bouts, 5 min activity bouts) sedentary time should be interrupted (a “sedentary break”) to yield health benefit has precluded more quantitative, actionable guidelines. To date, rigorous and methodical dose escalation experiments have not been conducted to elucidate effective and tolerated sedentary break doses. The objective of the proposed study is to determine the minimally effective dose (e.g., the lowest dose) for two elements of a sedentary break (frequency and duration) that yields improvements in established CVD risk factors. The maximally tolerated dose (e.g. the highest dose that does not cause undue physical/psychological distress) for both frequency and duration of sedentary breaks will also be determined. This study is a randomized crossover trial conducted under laboratory conditions among 324 adults without chronic medical conditions. Participants complete two trial conditions (8 h each), a sedentary break (intervention) condition and an uninterrupted sitting (control) condition, in a randomized order. The sedentary break condition consists of 1 of 25 possible frequency/duration combinations (e.g. walk every 30 min for 5 min), selected according to a Bayesian adaptive randomization method. Primary outcomes used to inform the adaptive randomization are glucose and blood pressure serially assessed over each trial condition. Constructs of dose toxicity (tolerability, safety, physical exhaustion/fatigue, and affect) are also serially assessed. This study will elucidate the minimally effective and maximally tolerated frequency and duration of a sedentary break that yields improvements in established CVD risk factors, information important for the development of quantitative sedentary behavior guidelines. This trial has been registered with the Clinical Trials Registry maintained by the National Library of Medicine at the National Institutes of Health on April 29, 2022. The registration ID is NCT05353322.

Increasing evidence highlights the efficacy of interruptions in prolonged sitting (i.e., activity/sedentary breaks) for improving cardiometabolic health, but precise conclusions and recommendations regarding the optimal interruption frequency remain poorly defined. This systematic review and meta‐analysis aimed to directly compare the effect of different frequencies of interrupting prolonged sitting on cardiometabolic health and to determine potential moderators. Randomized crossover trials with at least two frequency interruptions compared to a prolonged sitting condition were identified via systematic review. We compared the acute effects of high‐frequency (≤ 30 min per bout, HF) versus low‐frequency (> 30 min per bout, LF) interruption protocols on various cardiometabolic health outcomes via three‐level meta‐analysis with pooled effects evaluated within a random‐effects model and exploration of potential sources of heterogeneity through subgroup analyses. The quality of evidence was assessed using Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. Thirteen studies with 211 participants (24–66 years, 41% female) were included. When comparing HF to LF condition, the HF had a significantly greater reduction in glucose (9 studies [n = 740]; Hedge's g = −0.30, 95% CI [−0.57, −0.03], p = 0.03; I²‐level 3 = 42%, PI [−1.01, 0.41]). However, there was no difference in insulin (4 studies [n = 304]; Hedge's g = −0.22, 95% CI [−0.73, 0.29], p = 0.35; I²‐level 3 = 52%, PI [−1.18, 0.74]), triglyceride (3 studies [n = 484]; Hedge's g = 0.11, 95% CI [−0.10, 0.30], p = 0.29; I²‐level 3 = 0%, PI [−0.10, 0.30]), blood pressure (5 studies [n = 352]; Hedge's g = −0.06, 95% CI [−0.41, 0.28], p = 0.69; I²‐level 3 = 35%, PI [−0.81, 0.62]), and superficial femoral flow‐mediated dilation (3 studies [n = 98]; Hedge's g = −0.42, 95% CI [−2.43, 1.60], p = 0.47; I²‐level 3 = 78%, PI [−4.09, 3.25]) between the two conditions. The quality of evidence was low GRADE for all outcomes. The present study suggests that a higher sedentary interruption frequency might be more efficacious than a lower frequency/higher duration protocol for reducing glucose levels. Based on these findings, interrupting sedentary time at least, every 30 min may be an ideal strategy to improve glucose control.

The National Heart, Lung, and Blood Institute convened a virtual workshop in September 2022 to discuss “Optimal Instruments for Measurement of Diet, Physical Activity, and Sleep.” This report summarizes the proceedings, identifying current research gaps and future directions for measuring different lifestyle behaviors in adult population‐based studies. Key discussions centered on integrating report‐based methods, like questionnaires, with device‐based assessments, including wearables and physiological measures such as biomarkers and omics to enhance self‐reported metrics and better understand the underlying biologic mechanisms of chronic diseases. Emphasis was placed on the need for data harmonization, including the adoption of standard terminology, reproducible metrics, and accessible raw data, to enhance the analysis through artificial intelligence and machine learning techniques. The workshop highlighted the importance of standardizing procedures for integrated behavioral phenotypes using time‐series data. These efforts aim to refine data accuracy and comparability across studies and populations, thereby advancing our understanding of lifestyle behaviors and their impact on chronic disease outcomes over the life course.