Within-subject Effects Research Articles

Loneliness and sleep in the American Indian Blackfeet community

BackgroundSleep is largely understudied in American Indians (AIs), even though sleep is implicated in the chronic diseases which disproportionately affect AI communities. ObjectiveTo investigate relationships between daily self-reported loneliness and sleep as measured with actigraphy. MethodsIn a sample of 98 Blackfeet adults living on the Blackfeet reservation in Montana, we used Ecological Momentary Assessment and actigraphy over a week-long period to investigate relationships between loneliness and sleep. Loneliness was measured daily using the Short Loneliness Scale and actigraphy was used to measure total sleep time, sleep onset latency (SOL), wake after sleep onset (WASO), and sleep efficiency (SE). ResultsUsing a series of generalized linear mixed-effects models controlling for demographic characteristics, anxiety and depressive symptoms, and adverse childhood experiences, we found that those who were lonelier had higher WASO and SOL, and lower SE relative to those who were less lonely. Within-subject effects indicate that participants who were lonelier for a given day relative to their own weekly average had higher WASO that night relative to their own weekly average. ConclusionsOur findings provide initial preliminary evidence suggesting that loneliness may be a psychosocial factor which contributes to poor sleep in AI communities.

Acute Effects of Wearing Bite-Aligning Mouthguards on Muscular Strength, Power, Agility and Quickness in a Trained Population: A Systematic Review.

The purpose of the present systematic review was to determine the acute effects of wearing bite-aligning mouthguards on muscle strength, power, agility and quickness in athletes. A search of the current literature was performed using the electronic databases (until 1 May 2021) Web of Science, Scopus and Medline. The inclusion criteria were: (1) descriptive design studies; (2) with randomized clinical trials; (3) examining the within-subject acute effects of wearing mouthguards on functional and neuromuscular performance parameters; (4) in physical active, recreational or high-standard athletes. Twenty-seven studies met the inclusion criteria. Sixteen reported positive effects in some of the variables assessed, two reported negative effects and the rest found no significant differences. Overall, the main findings described in the literature are inconclusive concerning the neuromuscular advantages of using mouthguards in muscle strength, power, agility and quickness. These discrepancies might be related to several factors such as differences in testing protocols, poor control of the jaw magnitude and improper mouthguard designs. Despite these differences, after conducting the present systematic review, the authors speculate that jaw clenching while wearing custom-made, bite-aligning oral devices might promote beneficial effects in lower limb power actions, especially in jump ability and knee extension movements. Thus, athletes might consider the use of mouthguards, not only for their protective role but also for the potential ergogenic effects in specific actions, mainly those for which lower limb muscular power are required.

Supplemental Material for Narrative Theory IV: Within-Subject Effects of Active and Control Scarcity Narratives on Delay Discounting in Alcohol Use Disorder

Supplemental Material for Narrative Theory IV: Within-Subject Effects of Active and Control Scarcity Narratives on Delay Discounting in Alcohol Use Disorder

Volanesorsen, an Antisense Oligonucleotide to Apolipoprotein-CIII, Decreases Triglycerides and Increases Lipoprotein Lipase Activity in Partial Lipodystrophy

Partial lipodystrophy syndromes (PL) involve selective deficiency of adipose tissue, with regional deficiency of fat in the lower extremities and preservation or even excess fat in the face and neck. Clinical features typical of PL include severe insulin resistance, diabetes mellitus, hypertriglyceridemia and non-alcoholic fatty liver disease. Apolipoprotein CIII (Apo-CIII) is elevated in PL, and is thought to contribute to high TG by inhibiting lipoprotein lipase (LPL). However, prior studies of this drug in patients with LPL mutations demonstrated LPL-independent mechanisms of TG-lowering. We hypothesized that Volanesorsen, an antisense oligonucleotide (ASO) to apo-CIII, would decrease apo-CIII, increase LPL activity, and lower TG in PL. We further hypothesized that Volanesorsen would improve insulin resistance and glycemia by directing free fatty acids (FFA) into adipose tissue, rather than ectopic sites (e.g. liver) associated with insulin resistance. Five adults with PL and TG ≥500 mg/dL or TG≥200 with A1c >7.0% were enrolled in a 16-week placebo-controlled, randomized, double blind study of Volanesorsen, 300 mg SC weekly, followed by a 1-year open label extension. Here, we report within-subject effects of Volanesorsen lipids, glycemia and lipolysis, before and after 16 weeks of active drug. From week 0 to week 16, apoC-III decreased from 380 (246, 600) to 75 (26, 232) ng/mL, TG decreased from 503 (330, 1040) to 116 (86, 355) mg/dL; and LPL activity measured in post-heparin plasma utilizing the subject’s serum as activator increased from 22.0±3.0 to 35.5±5.9 nEq/ml/min. Free fatty acid turnover (measured by palmitate tracer studies) decreased from 0.41 (0.35, 0.45) to 0.25 (0.23, 0.29) mg/kg/min. There was no change in A1c (8.4±1.2 to 8.3±0.9%), however there was a decrease in HOMA-IR from 26 (20, 54) to 13 (9, 43) and an increase in peripheral insulin sensitivity (glucose infusion rate during euglycemic hyperinsulinemic clamp, 120 mU/m2/min) from 3.6±2.4 to 4.4±1.5 mg/kgFFM/min and in hepatic insulin sensitivity (% suppression of hepatic glucose production during clamp) from 78±19 to 90±13%. Adverse events include injection site reactions and decreased platelets. Volanesorsen decreased apo-CIII and triglycerides, at least in part through an LPL dependent mechanism, and may improve insulin resistance.

Using GAMMs to model trial-by-trial fluctuations in experimental data: More risks but hardly any benefit

• We compared two modeling approaches applied to data with by-trial fluctuations. • Linear Mixed-Effects Models (LMEMs) did not show excess false positive rates. • Generalized Additive Mixed Models (GAMMs) impaired between-subject power. • Randomization is sufficient defense against by-trial noise in experimental datasets. Data from each subject in a repeated-measures experiment form a time series, which may include trial-by-trial fluctuations arising from human factors such as practice or fatigue. Concerns about the statistical implications of such effects have increased the popularity of Generalized Additive Mixed Models (GAMMs), a powerful technique for modeling wiggly patterns. We question these statistical concerns and investigate the costs and benefits of using GAMMs relative to linear mixed-effects models (LMEMs). In two sets of Monte Carlo simulations, LMEMs that ignored time-varying effects were no more prone to false positives than GAMMs. Although GAMMs generally boosted power for within-subject effects, they reduced power for between-subject effects, sometimes to a severe degree. Our results signal the importance of proper subject-level randomization as the main defense against statistical artifacts due to by-trial fluctuations.

Influence of step-surface visual properties on confidence, anxiety, dynamic stability, and gaze behaviour in young and older adults.

Step-surface visual properties are often associated with stair falls. However, evidence for decorating stairs typically concerns the application of step-edge highlighters rather than the entire step-surface. Here we examine the influence of step-surface visual properties on stair descent safety, with a view to generating preliminary evidence for safe stair décor. Fourteen young (YA: 23.1±3.7years), 13 higher (HAOA: 67±3.5) and 14 lower (LAOA: 73.4±5.7) ability older adults descended a seven-step staircase. Older adults were stratified based on physiological/cognitive function. Step-surface décor patterns assessed were: Black and white (Busy); fine grey (Plain); and striped multicolour (Striped); each implemented with/without black edge-highlighters (5.5cm width) totalling six conditions. Participants descended three times per condition. Confidence was assessed prior to, and anxiety following, the first descent in each condition. 3D kinematics (Vicon) quantified descent speed, margin of stability, and foot clearances with respect to step-edges. Eye tracking (Pupil-labs) recorded gaze. Data from three phases of descent (entry, middle, exit) were analysed. Linear mixed-effects models assessed within-subject effects of décor (×3) and edge highlighters (×2), between-subject effects of age (×3), and interactions between terms (α= p<.05). Décor: Plain décor reduced anxiety in all ages and abilities (p=.032, effect size: gav=0.3), and increased foot clearances in YA and HAOA in the middle phase (p<.001, gav=0.53), thus improving safety. In contrast, LAOA exhibited no change in foot clearance with Plain décor. Patterned décor slowed descent (Busy: p<.001, gav=0.2), increased margins of stability (Busy: p<.001, gav=0.41; Striped: p <.001, gav =0.25) and reduced steps looked ahead (Busy: p =.053, gav =0.25; Striped: p =.039, gav =0.28) in all ages and abilities. This reflects cautious descent, likely due to more challenging conditions for visually extracting information about the spatial characteristics of the steps useful to guide descent. Edge highlighters: Step-edge highlighters increased confidence (p <.001, gav=0.53) and reduced anxiety (p <.001, gav=0.45) in all ages and abilities and for all décor, whilst removing them slowed descent in HAOA (p =.01, gav=0.26) and LAOA (p=.003, gav=0.25). Step-edge highlighters also increased foot clearance in YA and HAOA (p =.003, gav=0.14), whilst LAOA older adults showed no adaptation. No change in foot clearances with décor or step-edge highlighters in LAOA suggests an inability to adapt to step-surface visual properties. Patterned step surfaces can lead to more cautious and demanding stair negotiation from the perspective of visually extracting spatial information about the steps. In contrast, plain décor with step edge highlighters improves safety. We therefore suggest plain décor with edge highlighters is preferable for use on stairs.

Investigating the Effects of Seizures on Procedural Memory Performance in Patients with Epilepsy.

Memory complaints are frequently reported by patients with epilepsy and are associated with seizure occurrence. Yet, the direct effects of seizures on memory retention are difficult to assess given their unpredictability. Furthermore, previous investigations have predominantly assessed declarative memory. This study evaluated within-subject effects of seizure occurrence on retention and consolidation of a procedural motor sequence learning task in patients with epilepsy undergoing continuous monitoring for five consecutive days. Of the total sample of patients considered for analyses (N = 53, Mage = 32.92 ± 13.80 y, range = 18–66 y; 43% male), 15 patients experienced seizures and were used for within-patient analyses. Within-patient contrasts showed general improvements over seizure-free (day + night) and seizure-affected retention periods. Yet, exploratory within-subject contrasts for patients diagnosed with temporal lobe epilepsy (n = 10) showed that only seizure-free retention periods resulted in significant improvements, as no performance changes were observed following seizure-affected retention. These results indicate general performance improvements and offline consolidation of procedural memory during the day and night. Furthermore, these results suggest the relevance of healthy temporal lobe functioning for successful consolidation of procedural information, as well as the importance of seizure control for effective retention and consolidation of procedural memory.

Cognitive function in association with high estradiol levels resulting from fertility treatment

The putative association between hormones and cognitive performance is controversial. While there is evidence that estradiol plays a neuroprotective role, hormone treatment has not been shown to improve cognitive performance. Current research is flawed by the evaluation of combined hormonal effects throughout the menstrual cycle or in the menopausal transition. The stimulation phase of a fertility treatment offers a unique model to study the effect of estradiol on cognitive function.This quasi-experimental observational study is based on data from 44 women receiving IVF in Zurich, Switzerland. We assessed visuospatial working memory, attention, cognitive bias, and hormone levels at the beginning and at the end of the stimulation phase of ovarian superstimulation as part of a fertility treatment. In addition to inter-individual differences, we examined intra-individual change over time (within-subject effects).The substantial increases in estradiol levels resulting from fertility treatment did not relate to any considerable change in cognitive functioning.As the tests applied represent a broad variety of cognitive functions on different levels of complexity and with various brain regions involved, we can conclude that estradiol does not show a significant short-term effect on cognitive function.

The path to dissociative experiences: A direct comparison of different etiological models.

Severe dissociation is trauma-related, but a range of dissociative experiences are also prevalent in clinical populations that are not necessarily trauma-based (e.g., depression, anxiety disorders, and obsessive-compulsive disorders). These remain poorly understood as the dominant etiological model for dissociation relies on trauma. Importantly, dissociation in such samples predicts poor prognosis and high drop-out rates. We set out to better understand the aetiology of dissociative experiences in a mixed clinical (anxiety and depression) and community sample by exploring between- and within-subjects effects of two domains: psychological distress or negative affectivity (operationalized as anxiety and depression symptoms), and poor sleep quality, including disturbed dreaming. The idea that negative affectivity triggers dissociation (Distress Model) is inspired by the trauma model. The idea that poor sleep and unusual dreaming underlie dissociation (Sleep Model) has been suggested as a competing theory. We examined both models by exploring which domains oscillate alongside dissociative experiences. N=98 adults, half of them diagnosed with depression and anxiety and half community controls, underwent a structured clinical interview and completed questionnaires monthly for 6months. Support was found for both models in that each domain had a unique explanatory contribution. Distress evinced consistent effects that could not be explained by sleep or dreaming, both between individuals and across time. Oscillations in dissociation across months, when taking psychological distress into account, were better explained by unusual dreaming than traditional sleep quality measures. These findings cannot be generalized to highly-traumatized samples. A complex, integrated etiological model for dissociative experiences is warranted.

Longitudinal Stability of Spatial Inattention in Children With Perinatal Stroke

BackgroundSigns of contralateral hemispatial inattention may be witnessed in children following perinatal brain infarcts (lesions), and evidence shows a pattern distinct from that in adults. This study is a longitudinal analysis of children with perinatal infarcts, with the goals of determining the pattern of inattention found in children with left or right hemisphere lesions and whether this pattern shows signs of change over time. MethodsTwenty-one children with left hemishpere lesions, nine children with right hemisphere lesions, and 80 neurologically healthy control children were given the Infant and Toddler Neglect Task at two different time points. At time 1, median age was 1.54 years (interquartile range [IQR] = 0.92 to 2.29). At time 2, median age was 3.25 years (IQR = 2.23 to 5.00). A standardized scoring system was developed to compare the children’s preference for the left versus right side of space. ResultsChildren with left hemisphere lesions showed a significantly increased preference for the left side of space and a slightly decreased preference for the right side of space at time 1 and a significantly decreased preference for the right side of space at time 2 compared with controls. Children with right hemisphere lesions showed a significantly decreased preference for the left side of space and a significantly increased preference for the right side of space compared with controls at time 1 and a significantly decreased preference for the left side of space and a significantly increased preference for the right side of space compared with controls at time 2. There were no significant within-subjects effects across time. ConclusionsThese data suggest that mechanisms of hemispatial inattention affect children early in the developmental process and that hemispatial inattention in children with both left and right hemisphere perinatal lesions likely persists at least through the early elementary school years.

Tailoring a dissonance-based body image intervention for adult women in a proof of concept trial: The Women’s Body Initiative

Although historically conceptualized as problems of youth, recent research indicates that women of all ages experience body dissatisfaction and eating disorder (ED) pathology. Despite this, existing body image interventions predominantly target youth. The Body Project (BP) has extensive support for reducing ED risk factors in younger women and girls. The current proof-of-concept study investigated the feasibility, acceptability, and estimates of intervention effect sizes of a modified BP for adult women, the Women’s Body Initiative (WBI). Conducted in the Southwestern United States, adult women (N = 13) aged 29–70 (M = 49.1) participated in 4, 1-h weekly sessions, completing measures at baseline, post-intervention, and 3-month follow-up. Participants rated the program as highly feasible and acceptable. Within-subjects effects sizes were medium to large for primary outcomes (body dissatisfaction, ED pathology) and secondary outcomes (psychosocial impairment, negative affect, quality of life, nutritious food consumption, and sleep) through 3-months. Results suggest preliminary feasibility and acceptability of WBI for adult women, and support proceeding with a larger trial to investigate intervention efficacy.

The Effect of a Psychotherapy Protocol on Dream Awareness in Adults With Generalized Anxiety Disorder.

This study aimed to examine the effect of an Affective and Sensory Psychotherapy Protocol (ASPP) on dream awareness in adults with generalized anxiety disorder (GAD). For this purpose, 60 self-referred male and female adults were studied within a randomized clinical trial. The Generalized Anxiety Disorder 7-Item Scale and the Mannheim Dream Questionnaire were used at baseline, posttreatment, and 3-month follow-up. No significant difference was observed between patients in the experimental and control groups at baseline. Findings showed that patients in the experimental group had a significant increase in dream recall, attitude toward dreams, and the total dream score than individuals in the control group. However, no sex difference was observed in the results for within-subject and between-group effects in the current study. The present research supported the influence of an ASPP on dream awareness in adults with GAD.

Efficacy of single versus multiple exposure by electromagnetic modalities on gram-negative and positive bacterial strains in an in-vitro model.

ObjectivesThe primary purpose of the recent experiment was to scrutinize the dissimilarity between single and multiple exposures by electrotherapeutic modalities to determine the development of Gram-positive and Gram negative bacteria spectrum.Material and methodsBacterial strains employed in this study were Gram-negative bacteria such as Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumonae and Gram-positive bacteria such as Staphylococcus aureus, Staphylococcus saprophyticus and Streptococcus pyogenes. Fluence for Low level laser therapy (LLLT) (810 nm) was 40 J/cm2 for 80 s, for microwave (MWD) a dosage of 100-Watt with duration of 5 min and for magnetic field therapy (MT) duration of 30 min with 100% intensity was used.ResultsRepeated Measures of analysis of variances (RANOVA) for within-subject effects was used to detect a global significant change within the means at dissimilar time points. The experiments of within-subjects revealed a significant difference within groups, df of (3, 40), F value of 39.38 and a p value less than 0.001, representing a significant variation between the three groups between pre and post exposures. There was a significant variation between single exposure and multiple exposures in the experimental sample’s pre-post between the four groups with df (1, 40) f value of 2943.69 and p value less than 0.001. Scanning and Transmission electron microscopy images were also taken into account to determine the extent of damage caused to the bacterial cells surface topography in Gram negative and Gram positive spectrums.ConclusionThe study demonstrated that single high exposure with the LLLT appears to have the most emphatic effect followed by exposure by MWD and MT.

Do early birds share their worms? How prosocial behaviour and empathy vary across the day

Social behaviours have been proposed to follow circadian patterns across the course of the day, but empirical support is mixed. As a within-subject test of circadian effects on everyday behaviour, we conduct an experience-sampling study with a near-representative population of 285 Americans (7405 observations). Prosocial behaviour and empathy were both somewhat more frequent in the morning (d = 0.08). However, these non-linear patterns only described morning-type participants; evening-types had consistent (and lower) rates of prosocial behaviour and empathy across time-of-day. These patterns were explained by morning-types reporting more social opportunities earlier in the day. These findings suggest that small, within-subject diurnal effects on social behaviour occur in daily life, and that some circadian effects may be driven by situation selection.

Mandatory Physical Education Classes of Two Hours per Week Can Be Comparable to Losing More than Five Kilograms for Chinese College Students.

Despite releases of governmental guidelines for promoting physical fitness among the youth in China, the performance of college students in fitness tests has been declining over the past three decades. Obesity and physical inactivity have been proposed as two main causes. However, their relative importance for improving physical fitness remains unclear. To address this knowledge gap, we collected longitudinal data spanning four consecutive years on the physical fitness test for students from Nanjing University, China. Physical education classes of two hours per week were mandatory for the first two years. Using mixed effects models, we quantify the within-subject effects of weight, muscular endurance, sex, and mandatory physical education courses, among other variables, on physical fitness total score. We found that, in spite of the dominance of normal weight among the students, losing weight was positively associated with the total score, with significant sex differences in the associations. Compulsory exercise provided by physical education classes per week had strong positive impacts on the total score, comparable to losing weight of roughly 15–17 kg for males and 5–10 kg for females. Half sex difference in the total score was explained by male students’ poor performance in the muscular endurance represented by pull-ups. Our results suggest that college students in China should engage in physical activity of higher levels to improve their physical fitness, with a heightened awareness of extra fat under normal weight and insufficient muscular endurance.

No differences in delay discounting between smokers with and without HIV.

People with HIV (PWH) smoke cigarettes at much higher rates than the general population and evidence-based cessation methods are less effective, putting PWH at greater risk for negative health outcomes. It is critical to identify the factors that underlie this health disparity. Delay discounting-the decline in the value of a reward when it is delayed-may explain this disparity. This study aimed to (1) compare delay discounting between adult smokers with HIV and without HIV and (2) evaluate whether acute smoking abstinence disproportionately increases delay discounting among smokers with HIV. This sub-study was part of a larger study (NCT03169101) examining predictors of smoking cessation outcomes among smokers with HIV (n = 34) and smokers without HIV (n = 46) at two counterbalanced laboratory sessions (once smoking-as-usual and once following 24-h biochemically confirmed abstinence) then again, after 8 weeks of smoking cessation treatment. There were no significant differences in delay discounting rates between HIV status groups (p = 0.49) or within-subject abstinence effects (p = 0.70). However, smokers without HIV exhibited a significant increase in delay discounting following smoking cessation treatment compared to baseline (p = 0.02), whereas the change among smokers with HIV did not reach statistical significance (p = 0.09). These findings do not support differences in delay discounting as a reason for the lower success rates of HIV+ smokers at quitting. Although delay discounting may not explain the disparity in smoking rates between people with and without HIV, future work should focus on additional correlates of higher smoking rates and lower quit rates among people with HIV.

Korean Clear Speech Improves Speech Intelligibility for Individuals with Normal Hearing and Individuals with Hearing Loss.

Clear speech is an effective communication strategy to improve speech intelligibility. While clear speech in several languages has been shown to significantly benefit intelligibility among listeners with differential hearing sensitivities and across environments of different noise levels, whether these results apply to Korean clear speech is unclear on account of the language's unique acoustic and linguistic characteristics. This study aimed to measure the intelligibility benefits of Korean clear speech relative to those of conversational speech among listeners with normal hearing and hearing loss. We used a mixed-model design that included both within-subject (effects of speaking style and listening condition) and between-subject (hearing status) elements. We compared the rationalized arcsine unit scores, which were transformed from the number of keywords recognized and repeated, between clear and conversational speech in groups with different hearing sensitivities across five listening conditions (quiet and 10, 5, 0, and -5 dB signal-to-noise ratio) using a mixed model analysis. The intelligibility scores of Korean clear speech were significantly higher than those of conversational speech under most listening conditions in all groups; the former yielded increases of 6 to 32 rationalized arcsine units in intelligibility. The present study provides information on the actual benefits of Korean clear speech for listeners with varying hearing sensitivities. Audiologists or hearing professionals may use this information to establish communication strategies for Korean patients with hearing loss.

Watching Pornography Alone or Together: Longitudinal Associations With Romantic Relationship Quality

Pornography viewing has been cross-sectionally and longitudinally linked to poorer romantic relationship quality. However, only a few studies have looked at (1) the associations of changes in pornography viewing over time with relationship characteristics, (2) differential impacts of watching alone and watching with one’s partner, and (3) how gender moderates these associations. The current study utilizes multilevel modeling to assess for between- and within-subject effects of watching pornography alone versus together on romantic relationship quality over time. A random national sample of 1,234 individuals, who began the study in unmarried heterosexual romantic relationships of at least 2 months’ duration, completed five waves of mail-in surveys over a 20-month period. Watching pornography alone was generally associated with poorer relationship quality for men (e.g., lower relationship adjustment and commitment, less emotional intimacy), but better relationship quality for women. People who reported watching more pornography with their partner reported more relationship intimacy and increases in watching together over time were associated with increases in sexual intimacy. Both watching alone and watching together were related to higher levels of psychological aggression between partners, with few differences by gender. Implications for sex education, relationship education, and couples therapy will be discussed.

Intensity warping for multisite MRI harmonization

In multisite neuroimaging studies there is often unwanted technical variation across scanners and sites. These “scanner effects” can hinder detection of biological features of interest, produce inconsistent results, and lead to spurious associations. We propose mica (multisite image harmonization by cumulative distribution function alignment), a tool to harmonize images taken on different scanners by identifying and removing within-subject scanner effects. Our goals in the present study were to (1) establish a method that removes scanner effects by leveraging multiple scans collected on the same subject, and, building on this, (2) develop a technique to quantify scanner effects in large multisite studies so these can be reduced as a preprocessing step. We illustrate scanner effects in a brain MRI study in which the same subject was measured twice on seven scanners, and assess our method’s performance in a second study in which ten subjects were scanned on two machines. We found that unharmonized images were highly variable across site and scanner type, and our method effectively removed this variability by aligning intensity distributions. We further studied the ability to predict image harmonization results for a scan taken on an existing subject at a new site using cross-validation.

Using Ecological Momentary Assessment to Examine the Effects of Duty Status on Acute Stress and Tiredness in Firefighters: A Pilot Study.

Characterize firefighters' acute stress and tiredness by duty status (ie, "off night/day," "on night/day"). Thirty nine career firefighters completed three, eight-day smartphone-based ecological momentary assessment periods with seven surveys per day assessing stress and tiredness. Mixed-effects location scale models examined duty status effects on stress and tiredness. Firefighters' lowest stress and tiredness levels were when off-duty (β = 16.27 and β = 24.71, respectively) and their highest levels were when on-duty (β = 24.47 and β = 32.18, respectively). Within-subject effects of duty status accounted for a larger proportion of variability in stress and tiredness for all duty types, except for stress when "on-duty night/off-duty day." Firefighters had more similar stress and tiredness outcomes when they were on-duty and less similar outcomes when off-duty. This could be due to firefighters having more similar experiences when they are on- versus off-duty.