Sleep duration is significantly correlated with other physiological characteristics
the verdict
CONTESTED
contested - evenly split
refutedsupported
the weight of evidence
8 sources for · 4 against
Evidence regarding the correlation between sleep duration and other physiological characteristics is mixed, with some sources indicating significant correlations while others report null findings or lack of significant association.
<b>Introduction:</b> Blue light from electronic devices has a bad reputation. It has a wavelength which may influence our circadian rhythm and cause bad sleep. But there are other aspects of blue light exposure which are often overlooked, for example, it may influence performance and wellbeing. However, few resources summarize its effects systematically. Therefore, the goal of this systematic review was to distil the present evidence on blue light exposure and its influence on sleep, performance and wellbeing and discuss its significance for athletes. <b>Methods:</b> The databases that were searched were Cochrane, Embase, Pubmed, Scopus, and Virtual Health Library. The studies included investigated the influence of blue light exposure on either sleep, performance, wellbeing or a combination of those parameters on healthy humans. Quality assessment was done based on the quantitative assessment tool "QualSyst." <b>Results:</b> Summarizing the influence of blue light exposure, the following results were found (expressed as proportion to the number of studies investigating the particular parameter): Fifty percent of studies found tiredness to be decreased. One fifth of studies found sleep quality to be decreased and one third found sleep duration to be decreased. Half of the studies found sleep efficacy to be decreased and slightly less than half found sleep latency to be increased. More than one half of the studies found cognitive performance to be increased. Slightly more than two thirds found alertness to be increased and reaction time to be decreased. Slightly less than half of the studies found wellbeing to be increased. <b>Conclusion:</b> Blue light exposure can positively affect cognitive performance, alertness, and reaction time. This might benefit sports reliant on team-work and decision-making and may help prevent injury. Blue light might also have negative effects such as the decrease in sleep quality and sleep duration, which might worsen an athlete's physical and cognitive performance and recovery. Further research should explore if blue light can improve sleep, performance and wellbeing to significantly benefit athletic performance.
Sleep is widely recognized as an important factor in physical health and recovery, yet the amount
of sleep needed to support optimal physiological performance remains unclear. This study examined
whether nightly sleep duration predicts exercise-related performance measures using a large wearablebased
archival dataset consisting of over 10,000 adult participants. Single variable statistical tests,
including Pearson correlations, were used alongside multivariable modeling through a neural network
to evaluate relationships between sleep duration and performance indicators such as resting heart rate,
workout duration, burned calories, steps taken, workout intensity, and mood after exercise. Across all
analyses, no statistically significant or robust predictive relationships were identified between sleep
duration and performance outcomes. These null findings suggest that wearable datasets may mask true
sleep-performance relationships due to factors such as device variability, participant heterogeneity,
self-reported measures, and unmeasured confounding variables. Despite the absence of significant
associations, this study highlights important methodological challenges and provides direction for future
research using more standardized sleep tracking and controlled sleep study designs.
The inflammatory potential of the diet, as measured by the Dietary Inflammatory Index (DII®), has been repeatedly shown to be associated with various inflammatory markers and mental and physical health outcomes. Of specific importance, several cross-sectional studies revealed mixed results regarding the correlations between the DII and sleep outcomes. Hence, in the current paper, a systematic review that examines the associations between the DII, sleep duration, and sleep quality was performed. The PubMed database was systematically searched for studies published up to November 2023 following PRISMA guidelines. Only cross-sectional studies that assessed the DII, sleep duration, and sleep quality across healthy and unhealthy cohorts were included. Eleven and seven studies were included in the systematic review for sleep quality and duration, respectively. The results of the present systematic review show that pro-inflammatory diets may be associated with poor sleep outcomes (duration and quality); however, as the current literature is inconsistent and limited, further cross-sectional studies in larger cohorts are necessary to (i) explore this relationship to address this heterogeneity and (ii) explore populations that are more sensitive to diet-induced inflammation.
<h4>Importance</h4>Understanding the within-person association between daily screen use and sleep can help clarify whether this association reflects potentially causal effects or confounding factors.<h4>Objective</h4>To synthesize evidence on the within-person association between daily screen use and sleep among youth and to examine whether this association varies by screen type, sleep assessment method, or timing of screen use.<h4>Data sources</h4>Ovid MEDLINE, PsycINFO, SPORTDiscus, and Scopus were searched from inception to August 22, 2025, with forward and backward snowball searching. Data were analyzed in October 2025.<h4>Study selection</h4>Studies reporting on children, adolescents, and young adults aged 3 to 25 years that assessed sleep, measured screen time, and examined daily within-person associations between screen time and sleep were analyzed.<h4>Data extraction and synthesis</h4>Random-effects meta-analysis with cluster-robust variance estimation estimated pooled within-person correlations. Subgroup analyses examined moderating effects of screen type, assessment method, and timing.<h4>Main outcomes and measures</h4>The primary outcome was within-person correlations between screen time and sleep outcomes, including total sleep time, sleep onset, sleep onset latency, sleep efficiency, wake after sleep onset, and subjective sleep quality.<h4>Results</h4>A total of 25 studies reporting on 4562 participants were included. A small significant positive within-person correlation was found between screen time and sleep onset (r = 0.079; 95% CI, 0.010-0.149; P = .03), indicating later bedtimes on days with increased screen use. No significant associations were observed for total sleep time, sleep onset latency, sleep efficiency, wake after sleep onset, or subjective sleep quality. Moderator analyses revealed that the association between screen time and subjective sleep quality significantly differed by timing, with screen time after bedtime showing stronger negative correlation (r = -0.092) vs daily (r = -0.026) or evening (r = -0.005) assessments (P = .007). No other significant moderator effects were observed.<h4>Conclusions and relevance</h4>Per the results of this systematic review and meta-analysis, daily screen time has a small but significant within-person correlation with later sleep onset; however, short-term daily fluctuations in screen time appear to have minimal impact on sleep duration, efficiency, or quality. Screen time may delay bedtime but is not inherently detrimental to other aspects of sleep health in youth, contrasting with between-person studies showing stronger adverse associations.
Smoking is closely associated with significant disruptions in sleep architecture. Although previous studies have reported altered self-reported sleep quality in adolescent smokers, relatively few studies using polysomnography have objectively examined critical sleep microstructural components (i.e., slow-wave activity and sleep spindle characteristics) in young smokers. This study investigated changes in these electroencephalographic indices in adolescent smokers and their associations with smoking-related characteristics. We recruited 20 young smokers and 16 non-smokers, collecting their overnight polysomnography data. The Fagerström Test for Nicotine Dependence assessed dependence levels, and the pack-year index quantified cumulative smoking exposure. We analysed slow waves (0.5-4.5 Hz) in N3 sleep and spindles (11-16 Hz) in N2 sleep, quantifying parameters via the YASA toolbox. Smokers showed impaired N3 slow-wave integrity (reduced amplitude and slopes) and enhanced N2 spindle activity (increased density, frequency and duration). Slow-wave amplitude reduction correlated negatively with smoking indices, whereas spindle enhancements correlated positively. Sleep slow waves and spindles may serve as biomarkers for sleep quality in young smokers, deepening understanding of the sleep-smoking relationship.
A systematic review of the effects of water immersion thermotherapy (WIT) on sleep quality in healthy adults. A comprehensive search was conducted in PubMed, Cochrane Library, Web of science, Embase, Scopus, Ovid MEDLINE, Wiley Online Library, PEDro, CNKI, SinoMed and Yiigle databases. A meta-analysis method was adopted to evaluate the improvement of sleep quality by using WIT. By calculating the standardized mean difference (SMD) and its 95% confidence interval (CI), and selecting either a common effects model or a random effects model for data pooling and analysis. A total of ten randomized controlled trials were included in this study. The results showed that WIT significantly increased total sleep time (SMD = 0.63, P = 0.0438) and significantly improved sleep efficiency (SMD = 0.64, P = 0.0419). However, there were no significant effects on sleep latency (P = 0.0877) or the pittsburgh sleep quality index (PSQI). Furthermore, there were no significant effects on PSQI-total score (P = 0.1136), PSQI-subjective sleep quality (P = 0.3721), PSQI-sleep latency (P = 0.0864), PSQI-sleep duration (P = 0.1402), PSQI-sleep efficiency (P = 0.6793), PSQI-sleep disturbances (P = 0.0580), PSQI-use of sleep medication (P = 0.9991), or PSQI-day time dysfunction (P = 0.6525) among the various indicators of the PSQI. WIT can significantly prolong total sleep time and improve sleep efficiency, but has no significant effect on the improvement of subjective sleep quality, indicating that the sleep-improving effect of WIT has certain limitations.
This study aimed to investigate the relationship between sleep parameters and tear film hydration assessed by tear meniscus height (TMH), and to evaluate the usability of a mobile application for remote behavioral and physiological data collection.Eighteen healthy adults (mean age 29.6 ± 6.4 years) completed five consecutive days of linked measurements combining objective sleep tracking (using Fitbit Charge 4) and slit-lamp imaging of TMH under standardized conditions. Behavioral data on stress, caffeine intake, and smartphone use were collected via a custom mobile application, whose usability was assessed by the System Usability Scale (SUS).Ninety valid daily records were analyzed. TMH correlated positively with total sleep time (r=0.31, P=0.0033), REM sleep duration (r=0.28, P=0.0066), and sleep quality (r=0.32, P=0.0024). Each additional 30 min of REM sleep increased TMH by approximately 0.014 mm. Short sleepers (<6 h) showed significantly lower TMH (0.121 mm) than normal sleepers (≥6 h; 0.153 mm; P=0.0023). Stress and evening smartphone use were associated with reduced sleep quality and lower TMH. The mobile application achieved excellent usability (SUS = 87 ± 6).Our data indicate that sleep duration and architecture play essential roles in maintaining tear film stability. Behavioral habits that impair sleep continuity may thus directly affect ocular surface physiology. The combined use of wearable sensors and mobile self-reporting represents a practical approach to study
number of these brief arousals is significantly correlated with the magnitude of daytime sleepiness … pressure was correlated with nocturnal hypoxemia, whereas diastolic pressure correlated with obesity … baseline (sleep duration, mean ± SD, 7.61 ± 1.00 h). Reduced sleep duration should be considered
Sleep onset latency is significantly decreased. REM latency is significantly prolonged. Architecture: … muscle twitches, and other physiological phenomena. The usual duration is from milliseconds to … dur¬ ing developmental years.'® 3. Total sleep duration increases with body mass." 4. Release
Healthy sleep is known to contribute to psychosocial well-being. Pregnancy and postpartum could have profound influences on women’s psychosocial well-being related to physiological changes and interrupted sleep due to caring for the infant. The purpose of this study was to determine the associations between self-reported sleep characteristics and psychosocial well-being.
Forty-seven women who delivered a singleton infant after ≥ 37 weeks of gestation were interviewed at 6-8 weeks, 4 months, and 6 months after delivery. The Pittsburgh Sleep Quality Index (PSQI) was used to obtain sleep duration, sleep disturbance, and the global PSQI score, and the Epworth Sleepiness Scale total score was used to assess daytime sleepiness. The Edinburgh Postnatal Depression Scale, Perceived Stress Scale, and Rosenberg Self-Esteem Scale were used to assess psychosocial well-being, and a summary score of each instrument was calculated.
The self-reported nightly sleep duration decreased over time (535 ± 95, 505 ± 78, 488 ± 66 minutes, respectively at each timepoint, mean ± SD, p = 0.007). Other sleep characteristics did not change. There were also no significant changes over time in the scores of depressive symptoms, stress, or self-esteem. At 6-8 weeks postpartum, sleep disturbance was associated with stress (r = 0.32, p = 0.026) and self-esteem (r = -0.38, p = 0.008) so that women who had greater sleep disturbances perceived greater stress and lower self-esteem. These associations did not exist 4 months or 6 months after delivery. Sleep duration, global PSQI score, and sleepiness were not associated with any of the psychosocial measures.
Sleep disturbance is an important correlate of psychosocial well-being in early postpartum. The decreased sleep duration likely indicates recovering from pregnancy and delivery, and adapting to routine lifestyle.
National Institute On Minority Health And Health Disparities of the National Institutes of Health under Award Number R21MD012740
Background: Academic performance is related to cognitive functions and satisfied physiological needs such as proper sleep, a factor frequently overlooked by university students. Our aim was to investigate sleep-related variables, cognitive performance and stress level measured by heart rate variability among university students. Methods: A novel psychophysiological measurement system was used for data collection in which a screen-adapted questionnaire was used to collect data on sleep; gamified versions of standard psychological tests were used to assess cognitive performance, and ECG data were recorded by a wearable ECG sensor, all synchronized by a software. University students volunteered for anonymous testing that lasted approximately one hour. Results: Of the 107 students (mean age: 22.2 years, SD ± 2.22; 52% female), those who reported being well-rested achieved significantly higher overall cognitive performance ( p = 0.024). Sleep duration did not correlate with cognitive performance but longer sleep duration was associated with feeling rested ( rho = 0.326; p r = 0.195), higher values of which reflect higher autonomic stress load. Significant negative relation was found between cognitive performance and RMSSD ( r = −0.195), another HRV parameter, higher values of which allude to higher parasympathetic activity ( p = 0.050 for both). These findings suggest a link between mild arousal and performance. Conclusions: Being rested and lower autonomic stress load are positiv
<h4>Background</h4>Tension-type headache (TTH) is the most common primary headache, yet accompanying sleep disturbances have not been quantitatively synthesized.<h4>Methods</h4>PubMed, Embase, Web of Science, and the Cochrane Library were searched from inception to January 3, 2026, for observational studies reporting sleep outcomes in adults with TTH. The primary outcome was the prevalence of poor sleep quality assessed with the Pittsburgh sleep quality index (PSQI). Pooled estimates were calculated using random-effects models. Study quality was assessed with Joanna Briggs Institute checklists.<h4>Results</h4>Twenty-seven studies were included. Pooled prevalence of poor sleep quality in TTH was 67% (95% CI 53-79%; I<sup>2</sup> = 97%), stable across sensitivity and trim-and-fill analyses. Heterogeneity appeared partly related to recruitment settings. In five studies with non-headache controls, the odds of poor sleep quality were elevated but not significant (OR = 2.39; 95% CI 0.83-6.86; p = 0.08). The pooled mean PSQI score was 9.48 and significantly higher than controls (MD = 3.77; 95% CI 2.32-5.22; p < 0.01). Mean sleep duration was 6.61 h and did not differ significantly from controls. Insomnia was reported in 37%, excessive daytime sleepiness in 13%, and high OSA risk or PSG-defined OSA in 26%, with imprecise estimates. PSQI scores correlated robustly with depression (r = 0.51; FDR q = 0.005), whereas correlations with headache frequency and intensity were nominal and exploratory.<h4>Conclusions</h4>Poor subjective sleep quality is common in TTH, particularly among patients presenting to clinical settings, and is associated with depressive symptoms, with exploratory associations with headache burden, supporting consideration of sleep assessment in the clinical evaluation of TTH.
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