Circadian preference and physical and cognitive performance in adolescence: A scoping review

Morningness and Conscientiousness: A Meta-analysis, Online Survey and Resting fMRI Study

Morningness is associated with several positive health outcomes and personality traits such as conscientiousness. In the current report, meta-analysis demonstrated a significant association between morningness and conscientiousness, data that are consistent with previous meta-analyses. Further, survey report and resting-state functional Magnetic Resonance Imaging (rs-fMRI, N = 43) indicated that the relationship between morningness and conscientiousness was moderated by functional connectivity with the Default Mode Network (DMN). DMN connectivity has been implicated in a number of cognitive functions and higher connectivity in this network is associated with higher conscientiousness.

The Impact of Circadian Preferences on Quality of Life in Patients With Gastroesophageal Reflux Disease: An Evaluation Using the SF-36

Background/Aims

Gastroesophageal reflux disease (GERD) is a common gastrointestinal disorder that negatively impacts individuals' quality of life.

Methods

This study investigates the effect of circadian preferences on the quality of life in patients with GERD. A total of 152 participants (80 patients diagnosed with GERD and 72 healthy controls) were included in the study. Participants' circadian preferences were assessed using the morningness-eveningness questionnaire (MEQ), quality of life was evaluated with the SF-36 scale, and the severity of GERD symptoms was measured using the gastroesophageal reflux disease quality of life scale (GERD-QOL).

Results

The study's findings indicate that the quality of life and circadian preferences of GERD patients differ significantly from those of the control group. Correlation analyses revealed a positive relationship between SF-36 and MEQ, but no direct relationship was found between GERD-QOL and SF-36 or MEQ. Mediation analyses demonstrated that the effect of GERD-QOL on SF-36 is entirely mediated by circadian preferences.

Conclusions

These results highlight the significant impact of circadian preferences on the quality of life in GERD patients, suggesting that individuals with an evening chronotype may have lower quality of life. Our study contributes to the literature as one of the first to suggest that circadian preferences should be considered in the management of GERD.

Circadian Rhythm and Physical Fatigue Separately Influence Cognitive and Physical Performance in Amateur Athletes

BACKGROUND/OBJECTIVES

Circadian rhythm (CR) influences various physiological functions, including physical and cognitive performance, which fluctuate throughout the day. The present study aimed to investigate the combined and separate effects of CR and physical fatigue on cognitive and physical performance.

METHODS

A sample of 18 amateur athletes was subjected to a series of tests at three different times of the day: morning, afternoon, and evening. Fatigue was induced following an isokinetic concentric exercise combined with a 20 min treadmill run, followed by assessments of selected physical and cognitive tasks.

RESULTS

A repeated measure ANOVA did not reveal an interaction between CR and fatigue in cognitive performance (p > 0.05). However, a significant main effect of fatigue was observed in visual reaction time (VisRT) across all three timepoints. Moreover, peak torque (PT) and the peak torque fatigue index (PTFI) showed significant differences between the three times of the day, peaking in the evening.

CONCLUSIONS

Although we found no interaction between CR and the physical fatigue state on selected cognitive parameters at the three times of the day, a separate effect of fatigue on cognitive performance was identified. Additionally, physical parameters exhibited peak values occurring in the evening hours. Future research should further explore underlying mechanisms that potentially influence cognitive performance at different times of the day.

Exploring the nexus between sleep, chronotype, and non-cognitive predictors in university students: Implications for academic success

While the association between sleep-related variables and academic achievement is widely acknowledged, limited attention has been directed towards exploring non-cognitive predictors of academic achievement such as conscientiousness and self-regulation. In this study, we investigated the relationships between various sleep-related factors (circadian preference, chronotype, sleep duration, quality, and irregularity) and non-cognitive predictors (conscientiousness, self-regulation, self-efficacy, and achievement motivation) in 637 university students. Bivariate analyses revealed moderate to strong correlations among several sleep-related measures. Notably, distinctness, representing the subjective perception of daily changes, and daytime sleepiness exhibited negative associations with self-regulation, while high sleep quality was positively linked to robust self-regulation. These findings emphasize the importance of exploring various measures, particularly distinctness within circadian typology. Furthermore, we discuss the potential integration of sleep intervention programs with strategies aimed at enhancing self-regulation.

Relationship between Traumatic Experiences, Circadian Preference and ADHD Symptoms in Adolescents with ADHD Residing in Institutional Care: A Controlled Study

Circadian preference, describes biological and behavioural characteristics that influence the ability to plan daily activities according to optimal waking times. It is divided into three main categories: morning, evening and intermediate. In particular, the evening chronotype is associated with conditions such as Attention Deficit Hyperactivity Disorder (ADHD) and Post Traumatic Stress Disorder (PTSD). This study was conducted in three groups aged 14-18 years: The first group consisted of 34 adolescents diagnosed with ADHD who had been in institutional care for at least two years and had not used medication in the last six months. The second group included 29 adolescents with ADHD living with their families who had not used medication in the last six months. The third control group consisted of 32 healthy adolescents. The study utilized sociodemographic data forms, the Turgay DSM-IV Disruptive Behavior Disorders Rating Scale (T-DSM-IV-S) to measure ADHD symptoms, the Childhood Chronotype Questionnaire (CCQ), and the Childhood Trauma Questionnaire (CTQ). In institutionalized adolescents with diagnosed ADHD, ADHD and disruptive behavior symptoms were more severe. Increased trauma scores were associated with higher ADHD and disruptive behaviour symptom severity and evening chronotype. In the conducted mediation analysis, evening chronotype was identified as a full mediator in the relationship between trauma symptoms and ADHD symptoms, while it was determined as a partial mediator in the relationship between trauma symptoms and PTSD symptoms. In conclusion, traumatic experiences in institutionalized adolescents with diagnosed ADHD may exacerbate ADHD and disruptive behavior symptoms. Evening chronotype is associated with ADHD and disruptive behavior symptoms, and therefore, the chronotypes of these adolescents should be assessed. Chronotherapeutic interventions may assist in reducing inattention, hyperactivity, and behavioral problems.

Time-of-day effects on motor unit firing and muscle contractile properties in humans

Intrinsic factors related to neuromuscular function are time-of-day dependent, but diurnal rhythms in neural and muscular components of the human neuromuscular system remain unclear. The present study aimed to investigate the time-of-day effects on neural excitability and muscle contractile properties by assessing the firing properties of tracked motor units and electrically evoked twitch muscle contraction. In 15 young adults (22.9 ± 4.7 yr), neuromuscular function was measured in the morning (10:00), at noon (13:30), in the evening (17:00), and at night (20:30). Four measurements were completed within 24 h. The measurements consisted of maximal voluntary contraction (MVC) strength of knee extension, recording of high-density surface electromyography (HDsEMG) from the vastus lateralis during ramp-up contraction to 50% of MVC, and evoked twitch torque of knee extensors by electrical stimulation. Recorded HDsEMG signals were decomposed to individual motor unit firing behaviors and the same motor units were tracked among the times of day, and recruitment thresholds and firing rates were calculated. The number of detected and tracked motor units was 127. Motor unit firing rates significantly increased from morning to noon, evening, and night (P < 0.01), but there were no significant differences in recruitment thresholds among the times of day (P > 0.05). Also, there were no significant effects of time of day on evoked twitch torque (P > 0.05). Changes in the motor unit firing rate and evoked twitch torque were not significantly correlated (P > 0.05). These findings suggest that neural excitability may be affected by the time of day, but it did not accompany changes in peripheral contractile properties in a diurnal manner.NEW & NOTEWORTHY We investigated the variations of tracked motor unit firing properties and electrically evoked twitch contraction during the day within 24 h. The variation of motor unit firing rate was observed, and tracked motor unit firing rate increased at noon, in the evening, and at night compared with that in the morning. The variation in motor unit firing rate was independent of changes in twitch contraction. Motor unit firing rate may be affected by diurnal rhythms.