Time Of Day Effects Research Articles

Time of day effects on consumers’ online review characteristics: Evidence from the homestay platform

Considering the unique mechanism underlying time of day effects due to biological clock on cognition, mood, and behavior, this study seeks to investigate the time of day effects on consumers' online review characteristics in the context of homestay platforms. Mixed approaches were employed, where the textual analysis and econometric analysis were based on the dataset with 189,523 reviews received from Tujia and an online randomized experiment recruited 378 participants. The results show that in the daytime consumers are under high cognitive load and more likely to rely on affective processes rather than cognitive processes when they craft online reviews, and conversely in the nighttime. The emotional expressions extracted from review texts and reflected in online ratings suggest consumers' mood change along time of a day, which further influences their review texts crafting and online ratings posting. Positive (negative) emotions are found to be stronger (weaker) in the daytime than nighttime. This work is conducive to enrichment in extant literature in hospitality academia and numerous rationales and theories in psychology field. Our work suggests important implications for homestay platform operations, hosts' managerial strategies, and consumers’ decision-making.

Measuring urofecal glucocorticoid metabolites in broiler chicken: a noninvasive tool for assessing stress as a marker of welfare

The poultry industry is an important and still growing sector in many parts of the world. For ethical reasons and due to increased consumer awareness for animal welfare in production animals, it is of importance to establish a reliable and objective test system for monitoring and improving health and welfare. During the rearing process, broiler chickens are exposed to numerous potential stressors and management interventions (e.g. weighing of individual animals, preslaughter fasting and capture processes), but assessing the level of stress perceived by the animals entirely through behavioral observations can be challenging. Monitoring stress-related physiological markers, such as glucocorticoids, can be an accurate and presumably more objective addition. To avoid additional stressors induced by blood collection, a noninvasive approach using urofecal samples is advisable. However, a thorough validation is needed to establish a suitable test system for measuring stress hormone levels, including potential effects of the time of day of collection or the time that has elapsed since defecation. Therefore, the aim of this study was to test the stability of urofecal glucocorticoid metabolites (ufGCM) postdefecation, to determine time of day effects on ufGCM levels, and to investigate the effect of standard management procedures on ufGCM concentrations in broiler chickens. Our results revealed a time window of 4 h in which fecal samples from broilers can be collected without major alterations to the ufGCM concentrations. In this regard, a "fecal box" proved useful for collecting uncontaminated fresh samples. The time of day of sample collection did not influence ufGCM concentrations significantly. Moreover, the used assay proved to be sensitive enough to detect even small and short-lasting activations of the HPA axis induced by handling, confinement, and fasting. Thus, the system used can be a powerful and easy to apply tool in a chicken production setup for assessing stress as a marker of welfare in commercially housed broiler chickens, which in the long-term can also improve production, particularly with regard to process quality.

The timing of the mouse hind paw incision does not influence postsurgical pain

Chronobiological approaches have emerged as tools to study pain and inflammation. Although time–of-day effects on the expression of pain after injury have been studied, it remains unaddressed whether the timing of the injury itself can alter subsequent pain behaviors. The aim of this study was to assess postsurgical pain behaviors in a mouse hind paw incision assay in a circadian-dependent manner. Incisions were made at one of four equally spaced time points over a 24-hour period, with evoked and spontaneous pain behaviors measured using the von Frey mechanical sensitivity test, Hargreaves’ radiant heat paw-withdrawal test, and the Mouse Grimace Scale. Algesiometric testing was performed in C57BL/6 mice prior to and at multiple time points after incision injury, at the same time of day, until pain resolution. No statistically significant differences were observed between groups. This study adds to the literature on circadian rhythms and their influence on pain in the pursuit of more biologically informed pre- and postoperative care.

Evaluation of surface type and time of day on agility course performance.

Canine agility competitions are performed on a variety of surfaces. In the equine and human literature, surface type has been associated with speed, performance, and injury risk. The aim of this study was to evaluate the effect of general surface type and time of day on calculated speed (yards per second over a measured course distance) and course performance during the UKI Agility International (UKI) U.S. Open. We hypothesized that surface type would affect calculated speed, with sand being the slowest. Data on course performance from the 2021 and 2022 events were obtained directly from UKI. The officiating judge measured course length, automatic timers recorded dogs' course times, and speeds were calculated from these values. Three surfaces (dirt, grass, and sand) were compared across three categories of courses (jumpers, standard, and speedstakes). Differences in calculated speeds and qualifying rates were estimated using generalized estimating equations (GEE) to account for multiple runs by the same handler. Among jumpers courses, those run on sand in 2021 were markedly slower than those run on dirt. Grass and dirt were more similar in terms of average calculated speed, though some courses run on grass were significantly faster than courses run on dirt and vice versa. Time of day effects observed were inconsistent, with more variability observed for dirt and sand than for grass. There was a notable variation in calculate speed based on surface with sand being slowest, likely due to the increased energy cost required to run on sand due to its high compliance. Calculated speeds on grass and dirt appeared generally similar, but there was substantial variability of calculated speed among various courses, making comparison of surface effects challenging. Variables within the surface itself (such as compaction level and moisture content) likely play a role in the effects of surface on speed and performance. This study provides insight into the complexity of surface effects on performance in agility dogs and highlights the need for canine-specific surface studies on the effect of surface variables and how these relate to risk of development of musculoskeletal injuries.

Effect of immunotherapy-infusion time of day on survival of patients with advanced cancers: a study-level meta-analysis

Immune checkpoint inhibitors (ICIs) have become the standard of care for numerous malignancies. Emerging evidence suggests that the time of day (ToD) of ICI administration could impact the outcomes of patients with cancer. The consistency of ToD effects on ICI efficacy awaits initial evaluation. This meta-analysis integrates progression-free survival (PFS) and overall survival (OS) data from studies with a defined 'cut-off' ToD. Hazard ratios (HRs) [95% confidence interval (CI)] of an earlier progression or death according to 'early' or 'late' ToD of ICIs were collected from each report and pooled. Thirteen studies involved 1663 patients (Eastern Cooperative Oncology Group performance status 0-1, 83%; males/females, 67%/33%) with non-small-cell lung cancer (47%), renal cell carcinoma (24%), melanoma (20%), urothelial cancer (5%), or esophageal carcinoma (4%). Most patients received anti-programmed cell death protein 1 or anti-programmed death-ligand 1 (98%), and a small proportion also received anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) (18%). ToD cut-offs were 13:00 or 14:00 (i.e. ICI median infusion time), for six studies, and 16:00 or 16:30 (i.e. reported threshold for weaker vaccination responses) for sevenstudies. Pooled analyses revealed that the early ToD groups had longer OS (HR 0.50, 95% CI 0.42-0.58; P<0.00001) and PFS (HR 0.51, 95% CI 0.42-0.61; P < 0.00001) compared with the late ToD groups. Patients with selected metastatic cancers seemed to largely benefit from early ToD ICI infusions, which is consistent with circadian mechanisms in immune-cell functions and trafficking. Prospective randomized trials are needed to establish recommendations for optimal circadian timing of ICI-based cancer therapies.

Tracing diurnal differences in brain anatomy with voxel-based morphometry - associations with sleep characteristics

ABSTRACT Multiple aspects of brain functioning, including arousal, motivation, and cognitive performance, are governed by circadian rhythmicity. Although the recent rise in the use of magnetic resonance imaging (MRI) has enabled investigations into the macroscopic correlates of the diurnal brain processes, neuroanatomical studies are scarce. The current work investigated how time-of-day (TOD) impacts white (WM) and grey matter (GM) volumes using voxel-based morphometry (VBM) in a large dataset (N = 72) divided into two equal, comparable subsamples to assess the replicability of effects. Furthermore, we aimed to assess how the magnitude of these diurnal differences was related to actigraphy-derived indices of sleep health. The results extend the current knowledge by reporting that TOD is predominantly associated with regional WM volume decreases. Additionally, alongside corroborating previously observed volumetric GM decreases, we provide the first evidence for positive TOD effects. Higher replicability was observed for WM, with the only two replicated GM clusters being volumetric increases in the amygdala and hippocampus, and decreases in the retrosplenial cortex, with the latter more pronounced in individuals with shorter sleep times. These findings implicate the existence of region-specific mechanisms behind GM effects, which might be related to cognitive processes taking place during wakefulness and homeostatic sleep pressure.

Time of Day Effects on Exercising in Cardiac Rehabilitation.

Time of Day Effects on Exercising in Cardiac Rehabilitation.

OR34-05 Second Phase Insulin Secretion Varies By Time Of Day And Body Mass Index

Abstract Disclosure: S. Naaman: None. S. Sintetas: None. E. Van Cauter: None. E.C. Hanlon: None. Diurnal variation in insulin secretion (ISR) is documented in healthy adults with and without obesity. However, in previous studies, the caloric content of meals varied across the day or the analysis focused solely on morning versus evening differences. It remains unclear if dietary intake timing is associated with metabolic response differences to the same dietary challenge if presented across a full day in individuals categorized as lean (L), with overweight (OW) or obesity (OB). Thus, we examined ISR following consumption of identical meals, equally spaced across the day, in a lab setting with controlled sleep and energy expenditure. Our study included 74 individuals; 41 lean (19 women), 14 overweight (4 women), and 19 obese (14 women). Obstructive sleep apnea (OSA), a known confounder of glucose metabolism, was an exclusion criterion. Mean age between groups was similar (L, 25.2 ± 5.3yrs vs OW, 27.0 ± 6.6yrs vs OB, 32.2 ± 7.6yrs). BMI was 38 ± 5.9 kg/m2 in the OB, 27 ± 1.2 kg/m2 in the OW, vs 22 ± 1.8 kg/m2 in the L groups, respectively (p &amp;lt; 0.0001). We collected blood samples continuously at regular intervals over a 24hr period in which participants ate isocaloric identical high carbohydrate meals (20% fat, 68% carbohydrate, 12% protein) at 0900, 1400, and 1900; each meal was 33% of total caloric intake. Serum C-peptide was measured using high-sensitivity chemiluminescence assays (Immulite). ISR was derived from plasma C-peptide levels by mathematical deconvolution using a two-compartment model for C-peptide clearance. Each profile was expressed as a percentage of individual 24hr mean ISR to examine the profile wave shape independently of individual differences in mean ISR. We examined 2 phases of ISR following meal ingestion; 1st phase (AUC, 0 - 1.5hrs) and 2nd phase (AUC, 1.5hrs - 3.5hrs). The profiles were analyzed with ANOVA for repeated measures with participants as a random factor and mealtime, group (L, OW, OB), and interaction “mealtime by group” as fixed effects. Despite 3 equally spaced identical meals, significant differences emerged. Irrespective of BMI, 1st phase relative ISR was similar across breakfast, lunch and dinner. Second phase relative ISR, however, revealed significant time of day effects; with midday eliciting the highest relative ISR for all groups (p = 0.0002). Significant time x group effects emerged in the 2nd phase such that relative ISR varied across the day, differently for each group (p &amp;lt; 0.0001). Specifically, 2nd phase relative ISR was lowest following dinner in those with obesity. This is the first study to compare 24hr profiles of ISR in healthy individuals at multiple BMI ranges, without OSA, in an experimental setting of 3 equally spaced identical meals. These findings imply that the midday meal elicits the highest ISRs, irrespective of BMI. Further, BMI impacts ISR across the day in response to identical meals. These findings have implications for obesity management. Presentation: Sunday, June 18, 2023

Time of Day Effects on Anaerobic Performance Using a Nonmotorized Treadmill.

Renziehausen, JM, Bergquist, AM, Park, J-H, Hill, EC, Wells, AJ, Stout, JR, and Fukuda, DH. Time of day effects on anaerobic performance using a nonmotorized treadmill. J Strength Cond Res 37(10): 2002-2007, 2023-The purpose of this study was to determine the effects of time of day on performance during a maximal effort sprinting assessment (30nmt) and determine potential differences based on chronotype and sex. Twenty-six recreationally active men (n = 12) and women (n = 14) between the ages of 18 and 35 years old (21.5 ± 2.4 years) completed the 30nmt at 9:00 am, 2:00 pm, and 7:00 pm in a randomized order over a 24-hour period. Resting heart rate and temperature assessments were taken at each visit. A dietary recall and the Morningness-Eveningness Questionnaire were used to assess kilocalories (kcals) and chronotype, respectively. Two-way (time x sex) repeated measures analyses of variance were conducted to determine differences in peak/mean power, peak/mean velocity, distance, resting heart rate, temperature, and kcals at each time point. Paired sample t tests were used to assess peak and nadir of each performance variable. A significance level was set at p < 0.05. There was a significant main effect for temperature (p < 0.001), resting heart rate (p = 0.007), and pre-exercise caloric intake (p = 0.021) throughout the day. No significant main effects for time were found for peak power (p = 0.766), mean power (p = 0.094), peak velocity (p = 0.497), mean velocity (p = 0.193), or distance (p = 0.262). There were no significant time × sex interactions for any dependent performance variables (p > 0.05). Significant differences were shown between the peak and nadir of each performance variable (p < 0.001). There were no significant differences in performance during maximal effort anaerobic assessments shown throughout the day; however, peak/nadir of performance times may be individualized and differ between morning types and intermediate types.

Chronotype and Time of Day Effects on a Famous Face Recognition Task with Dynamic Stimuli.

Chronotype and Time of Day (ToD) can modulate several aspects of cognitive performance. However, there is limited evidence about the effect of these variables on face recognition performance, so the aim of the present study is to investigate this influence. For this, 274 participants (82.5% females; age 18-49 years old, mean = 27.2, SD = 1.82) were shown 20 short videoclips, each gradually morphing from a general identity unfamiliar face to a famous face. Participants should press the spacebar to stop each video as soon as they could identify the famous face, and then provide the name or an unequivocal description of the person. Analysis of response times (RT) showed that evening-types recognised the faces faster than morning-types. Considering different ToD windows, the effect of chronotype was only significant in the 13h-17h and in the 21h-6h time-windows. Altogether, results suggest an advantage of evening-types on famous face recognition using dynamic stimuli with morning-types, being particularly slower during their non-optimal period.

Time of Day Effects in the Relationships Between Daytime Sleepiness, Current Arousal, and Cognitive Performance.

Daytime sleepiness is commonly reported among older adults. Additionally, aging is associated with a shift toward greater alertness in the morning that wanes throughout the day. The impact of time of day of testing on the relationships between daytime sleepiness and cognition is unknown. We explored the effects of time of testing in relation to self-reported daytime sleepiness/current arousal and cognition among 133 older adults. Time of testing moderated the relationship between daytime sleepiness and immediate learning/memory, with greater sleepiness being associated with poorer performance in the afternoon, but not morning. Time of testing also moderated the relationship between current arousal and processing speed, with lower arousal being associated with worse performance in the afternoon. These findings suggest that time of testing is important to account for when assessing sleepiness and cognition in older adults and that consideration should be given to how sleepiness is measured.

THE EXPERIENCE OF SUBJECTIVE AGE DURING EVERYDAY LIFE

Abstract Empirical work has shown that subjective age is susceptible to momentary fluctuation throughout the day, and in certain contexts like challenging cognitive evaluations. We propose and test a contextual model that describes how momentary experiences impact subjective age, which in turn impacts daily activities and well-being. Using an experience sampling approach, 200 participants were asked to complete 6 surveys per day for a week. Questions asked about the task they were engaged in, including mental, physical and social engagement, challenge, motivation, confidence, and enjoyment. Participants also completed a manipulation of mental challenge and reported their momentary subjective age. Preliminary multilevel models show that certain momentary factors, such as whether participants were enjoying a task or found the task engaging, predict fluctuations in subjective age. We will also discuss moderators, subjective age domains, time of day effects, and the cross-lagged influence of cognitive stressors over time.

Exploring the usage of supervised driving automation in naturalistic conditions

This study reports usage of supervised automation and driver attention from longitudinal naturalistic driving observations. Automation inexperienced drivers were provided with instrumented vehicles with adaptive cruise control (ACC) and lane keeping (LK) features (SAE level 2). Data was collected comparing one month of driving without support to two months where drivers were instructed to use automation as desired.On highways, level 2 automation was used respectively 63% and 57% of the time by Tesla and BMW users, with peak usage during slow stop-and-go traffic (0–30 km/h) and higher speeds (>80 km/h). On roads with speed limits below 70 km/h, automation was used less than 8%, and use on urban roads was incidental rather than habitual. Automation usage increased with time in trip, but no clear time of day effects were found. Head pose data could not classify driver attention, and we recommend gaze tracking in future studies. Head pose deviation was selected as alternative indicator for monitoring activity. Comparing among forms of automation usage on the highway, head heading deviation was smallest during ACC use, but did not differ between automation and baseline manual driving. Head heading deviation during manual driving was smaller in the baseline than the experimental phase, which suggests that motives for manual highway driving may be attention related. Automation usage did not change much over the first 12 weeks of the experimental condition, and there were no longitudinal changes in head pose deviation.

Abstract 096: Adrenal-specific KO Of The Circadian Clock Protein Bmal1 Alters Blood Pressure Rhythm

BMAL1 is a core circadian clock protein that regulates most physiological functions, including blood pressure (BP). Global BMAL1 knockout (KO) male mice exhibit reduced, non-dipping BP and loss of diurnal rhythm of renal sodium (Na) excretion. Although, BP and renal Na excretion rhythm remained intact in kidney-specific BMAL1 KO male mice. The adrenal gland synthesizes hormones which influence BP rhythm and renal electrolyte handling. The role of adrenal BMAL1 in the regulation of BP and renal function remains unknown. The goal was to test the hypothesis that adrenal BMAL1 is required for normal circadian rhythms of BP and renal Na excretion. Adrenal-specific aldosterone synthase Cre positive (AS)-BMAL1 KO male mice ( n =5) and littermate Cre negative, floxed control (CNTL) male mice ( n =6) underwent a telemetry study to measure BP. Cosinor analysis was performed to assess BP rhythms. During telemetry recordings, mice were placed in metabolic cages for 5 days on a normal salt diet. The latter 3 days, 12 h urine samples were collected before each light-dark Zeitgeber (6AM and 6PM/ Zeitgeber Time (ZT)0 and ZT12) to measure night/day patterns in renal Na excretion. Kidneys were collected from a separate cohort of mice ( n =7-8/genotype) at ZT0 and ZT12 for gene expression analysis of key Na transporters. No BMAL1-dependent changes in the 24 h averages for BP were observed. Cosinor analysis revealed significant differences in BP rhythm, however. The period (time taken for a full circadian cycle, ~24 h) was significantly shortened for BP in AS-BMAL1 KO mice vs. CNTL (23 h 31 vs 24 h 16, p =0.01). Acrophase (the time at which BP peaks) was shifted ~2 hours later in KO mice (KO ZT17 h 38 vs CNTL ZT15 h 45, p =0.002). The MESOR (midline estimating statistic of rhythm) of BP remained similar between groups (KO 133.5 mmHg vs CNTL 132.7 mmHg, p =0.904). Day/night Na excretion was not different in AS-BMAL1 KO mice vs. CNTL (ANOVA interaction p =0.168). This was consistent with a lack of genotype effects on gene expression for NCC, α, β, or γ ENaC. Significant time of day effects were observed for all 4 genes (all with p &lt;0.001). In conclusion, BMAL1 KO in the adrenal gland altered BP rhythm, with no changes in renal Na excretion. This work is the first to investigate the role of adrenal BMAL1 on BP regulation.

The effect of time of day on adolescent fast bowling performance: A pilot study

The game of cricket is played at various times of the day and no studies have investigated the time of day effects on perceptual, physical and performance measures of cricketers. Therefore, the purpose of this study was to focus on adolescent fast bowlers and their responses when bowling at different times of the day. First team, adolescent male fast bowlers (N = 5, Mean age 17.00 ± 0.55 years; stature 185.2 ± 6.5 cm and mass 86.06 ± 17.56 kg) were required to complete a fast-bowling simulation protocol whereby perceptual, physical and bowling-specific performance measures were tested at three different times of day (10:30, 14:30, 18:30). Over all the spells over one was significantly slower than all the other overs. There were no significant changes in bowling speed between the time intervals. However, there was a large increase in bowling speed at 14:30 compared to 10:30 (ES – 1.25) and a moderate increase in bowling speed (ES = 0.67) between 10:30 and 18:30. There was no significant change in accuracy at the different time intervals although it was best at 10:30 followed by 18:30 although the latter had a greater variance. In conclusion, this investigation found time of day did not significantly impact the responses, but the effects sizes show that bowling accuracy was worst at 14:30 despite the other parameters, such as speed of delivery, being best at this time, which may suggest a speed-accuracy trade-off. Additionally, both 10:30 and 18:30 were found to be times conducive to bowling performance with regards to accuracy.

The Effects of Aging and Time of Day on Inhibitory Control: An Event-Related Potential Study.

Time of day (TOD) influences on executive functions have been widely reported, with greater efficiency demonstrated at optimal relative to non-optimal TOD according to one’s chronotype (i.e., synchrony effect). Older adults (OAs) show declines in inhibitory control and are more sensitive to the effects of circadian variation on executive functioning. To date, no studies have investigated the effects of TOD and aging on executive functioning using electrophysiological measures. The present study investigated the effects of aging and TOD on the neural correlates of inhibitory processing (N2 and P3) using event-related potentials (ERPs). Go-NoGo and Flanker tasks were administered to 52 OAs of morning chronotype and 51 younger adults (YAs) of afternoon-to-evening chronotype who were randomly assigned to morning or afternoon test sessions, with the optimal TOD for OAs in the morning and for YAs in the afternoon/evening. While behavioral results demonstrated no TOD effects, ERPs indicated synchrony effects. Both YAs and OAs showed greater modulation of Go-NoGo N2 and greater P3 amplitude during the non-optimal than optimal TOD, consistent with the synchrony effect. For the Flanker task, age differences in P3 amplitude were only apparent during the non-optimal TOD. These results suggest that processes associated with inhibitory control are differentially affected by TOD and aging, with age-related reductions in inhibitory efficiency during off-peak test times on measures of interference control. These findings highlight the sensitivity of ERPs to detect TOD effects in the absence of behavioral differences, confirm more pronounced TOD effects in OAs relative to YAs on ERP measures of interference control, and reinforce the need to assess and control for circadian typology in research studies.

The effects of feed restriction, time of day, and time since feeding on behavioral and physiological indicators of hunger in broiler breeder hens

Broiler breeder chickens are commercially feed restricted to slow their growth and improve their health and production, however, there is research demonstrating that this leads to chronic hunger resulting in poor welfare. A challenge in these studies is to account for possible daily rhythms or the effects of time since last meal on measures relating hunger. To address this, we used 3 feed treatments: AL (ad libitum fed), Ram (restricted, fed in the morning), and Rpm (restricted, fed in the afternoon) to control for diurnal effects. We then conducted foraging motivation tests and collected home pen behavior and physiological samples at 4 times relative to feeding throughout a 24-h period. The feed treatment had the largest influence on the data, with AL birds weighing more, having lower concentrations of plasma NEFA, and mRNA expression of AGRP and NPY alongside higher expression of POMC in the basal hypothalamus than Ram or Rpm birds (P < 0.001). R birds were more successful at and had a shorter latency to complete the motivation test, and did more walking and less feeding than AL birds in the home pen (P < 0.01). There was little effect of time since last meal on many measures (P > 0.05) but AGRP expression was highest in the basal hypothalamus shortly after a meal (P < 0.05), blood plasma NEFA was higher in R birds just before feeding (P < 0.001) and glucose was higher in Ram birds just after feeding (P < 0.001), and the latency to complete the motivation test was shortest before the next meal (P < 0.05). Time of day effects were mainly found in the difference in activity levels in the home pen when during lights on and lights off periods. In conclusion, many behavioral and physiological hunger measures were not significantly influenced by time of day or time since the last meal. For the measures that do change, future studies should be designed so that sampling is balanced in such a way as to minimize bias due to these effects.

Slow oscillation-spindle coupling strength predicts real-life gross-motor learning in adolescents and adults.

Previously, we demonstrated that precise temporal coordination between slow oscillations (SOs) and sleep spindles indexes declarative memory network development (Hahn et al., 2020). However, it is unclear whether these findings in the declarative memory domain also apply in the motor memory domain. Here, we compared adolescents and adults learning juggling, a real-life gross-motor task. Juggling performance was impacted by sleep and time of day effects. Critically, we found that improved task proficiency after sleep lead to an attenuation of the learning curve, suggesting a dynamic juggling learning process. We employed individualized cross-frequency coupling analyses to reduce inter- and intragroup variability of oscillatory features. Advancing our previous findings, we identified a more precise SO-spindle coupling in adults compared to adolescents. Importantly, coupling precision over motor areas predicted overnight changes in task proficiency and learning curve, indicating that SO-spindle coupling relates to the dynamic motor learning process. Our results provide first evidence that regionally specific, precisely coupled sleep oscillations support gross-motor learning.

Chronotype and time of day effects on verbal and facial emotional Stroop task performance in adolescents

ABSTRACT This study investigated chronotype and time of day effects on lexical and facial emotion processing tasks and explored relationships with sleep quality and mental health outcomes. Participants were 351 Taiwanese adolescents (204 males) aged 13 to 16 years of age who completed both a Facial-Emotional Stroop and a Lexical-Emotional Stroop task at 08:00–10:00 am or at 14:00–16:00 pm. Chronotype was measured using the Morningness-Eveningness Questionnaire (MEQ) and grouped into Morning (n = 46), Intermediate (n = 248) or Evening types (n = 57). Participants completed validated measures of sleep quality (PSQI) and mental health difficulties (DASS-21). The study observed independent effects of time of day and chronotype on the Facial-Emotional Stroop task. Independent of chronotype group, delayed reaction times to anger stimuli were observed in adolescents tested in the morning. Younger adolescents with an Evening chronotype showed delayed responses to anger faces independent of the time of testing. Facial-Emotional Stroop task performance correlated with reported sleep quality and mental health only in Evening chronotypes, with attenuated responses to anger versus neutral stimuli associated with poorer sleep quality and worse mental health outcomes. An exploratory simple mediation analysis indicated that the relationship between attenuated responses to anger and greater mental health difficulties was fully mediated by poorer sleep quality. This study provides evidence of diurnal and chronotype-related variation in facial threat-related processing in typical adolescent development. It also indicates how social emotional processing is vulnerable to sleep disruptions and is linked to the greater mental health problems observed in adolescents with an eveningness profile.

Sharper in the morning: Cognitive sundowning revealed with high‐frequency smartphone testing

AbstractBackgroundIn Alzheimer’s disease (AD), patients and caregivers often report a pattern of increasing cognitive and behavioral difficulties in evening hours, known colloquially as “sundowning.” Here, we describe the first known attempt to capture circadian fluctuations in cognition in humans at risk for AD using a novel smartphone assessment that samples cognition rapidly and repeatedly over a 7‐day period. We hypothesized that cognitive sundowning would manifest among individuals with abnormal AD biomarkers, even in preclinical stages of AD.MethodsOlder adults (N=168, Ages 61‐94 years) were asked to complete 4 brief smartphone‐based testing sessions per day for 7 consecutive days at quasi random intervals throughout the day, from morning until evening. Tests included associate memory, processing speed, and visual working memory tasks (Figure 1). Cerebrospinal fluid biomarkers for beta amyloid (Ab42) and phosphorylated tau181 (ptau) were collected within ∼3 years of smartphone tests. Scores from morning hours (range ∼5am – 12pm) were averaged for comparison with averaged scores from evening hours (after 12pm). Mixed effect models evaluated time of day effects by CSF biomarker status and clinical status.ResultsParticipant characteristics are provided in Table 1. Models with terms for age, gender, education, APOE e4 status, and Clinical Dementia Rating™ Sum of Boxes tested the interaction between time of day and CSF ptau/Ab42 ratio in predicting cognition (Figure 2). Compared to those with normal biomarkers, participants with abnormal CSF ptau/Aβ42 ratio had worse associate memory (p=0.03) and processing speed performance (p=0.026) in evening hours. On processing speed, participants with abnormal ptau/Aβ42 ratios were slower by an average of 700ms in the evening compared to those with normal ptau/Aβ42 ratios tested in morning hours. When models were run in cognitively normal participants only, a similar pattern was observed, confirming the hypothesis that increasing loads of AD pathology result in worse cognitive performance in evening hours prior to symptom onset.ConclusionOur results provide the first known evidence of cognitive sundowning in preclinical and early symptomatic AD and suggest that time of day is an important consideration for studies of cognition in AD populations.