Effect of different nap opportunity durations on short-term maximal performance, attention, feelings, muscle soreness, fatigue, stress and sleep

The impact of strategic napping on peak expiratory flow and respiratory function in young elite athletes

Respiratory health is a critical determinant of athletic performance, and the utilization of restorative strategies, such as strategic napping, may offer a competitive edge to athletes. This study investigates the effects of nap duration on the respiratory function of young elite athletes who have achieved top rankings national competitions. Participants engage in three test sessions with varying nap durations: no nap (N0), a 25-minute nap (N25), and a 45-minute nap (N45), with a minimum 72-hour interval between sessions. Respiratory parameters including Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), FEV1/FVC ratio, Peak Expiratory Flow rate (PEF), Forced Expiratory Flow at 25-75% of FVC (FEF25-75%), and Forced Expiratory Time (FET) are assessed. Results reveal a significant enhancement in PEF values following a 45-minute nap (N45) compared to the no-nap control (N0) [F1 - 11=7.356, p =.004, ηp2 = 0.401, (95% CI for difference: -1.56 to - 0.056)], indicating a potential positive influence of napping on maximum expiratory flow rate and, consequently, athletes' respiratory performance. While no significant changes are observed in other respiratory parameters across different nap durations, these findings underscore the potential benefits of strategic napping in optimizing respiratory health in young elite athletes.

The Impact of Daytime Napping Following Normal Night-Time Sleep on Physical Performance: A Systematic Review, Meta-analysis and Meta-regression

BACKGROUND

Daytime napping is used by athletes as a strategy to supplement night time sleep and aid physical performance. However, no meta-analytical overview regarding the impact of napping following a night of normal sleep (7-9 h) on physical performance is available.

OBJECTIVE

The aim of this study was to evaluate the effect of daytime napping following normal night-time sleep on physical performance in physically active individuals and athletes.

METHODS

This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Seven electronic databases (i.e., PubMed, Web of Science, Scopus, SPORTDiscus, CINAHL, SCIELO, and EBSCOhost) were used to search for relevant studies that investigated the impact of daytime napping, following normal night-time sleep, on physical performance in physically active individuals and athletes, published in any language, and available before September 01, 2022. Studies that included assessments of any physical performance measures were included. QualSyst was used to assess the methodological quality of the studies.

RESULTS

Of 18 selected articles, 15 were of strong quality and 3 were of moderate quality. Compared with no-nap conditions, physically active individuals and athletes who napped experienced an increase in highest distance (effect size [ES] 1.026; p < 0.001) and total distance (ES 0.737; p < 0.001), and a decrease in fatigue index (ES 0.839, p = 0.008) during the 5-m shuttle run test (5MSRT). However, napping yielded no effect on muscle force (ES 0.175; p = 0.267). No effect of napping was found in one study that measured sprint performance and in two studies that measured performance during the 30-s Wingate test. Two of three studies reported an increase in jump performance after napping. Two of three studies reported an increase in repeated sprints after napping. One study reported an increase in upper-body power performance after napping, and napping was beneficial for endurance performance in one of two studies.

CONCLUSION

Following normal sleep, napping is beneficial for the performance of the 5MSRT, with no significant effect on muscle force. No firm conclusions can be drawn regarding other physical performance measures due to the limited number of studies.

Association of Midday Napping with All-Cause Mortality in Chinese Adults: A 8-Year Nationwide Cohort Study

This study aimed to investigate the longitudinal association of estimated daytime nap duration with all-cause mortality in Chinese adults. We conceived a prospective cohort design using adult survey data of the baseline and four follow-up waves (2010-2019) from China Family Panel Studies. Cox frailty models with random intercepts for surveyed provinces were used to estimate risks of all-cause mortality associated with midday napping. Trend and subgroup analyses were also performed stratified by demographic, regional and behavioral factors. Compared with non-nappers, those who reported a long napping duration (≥60 min/day) had an increased risk of all-cause mortality, while shorter napping (<60 min) showed no association with mortality. We observed significant trends for greater risks of mortality associated with longer nap duration. Long nap-associated higher risk of all-cause mortality was seen in a group of nocturnal sleep duration ≥9 h. We identified stronger associations of long nap with mortality among adults aged over 50 years, those with lower BMI (<24 kg/m2), residents in rural regions and unregular exercisers. Long midday napping is independently associated with higher risks of all-cause mortality in Chinese adults.

The combined effects of napping and self-selected motivation music during warming up on cognitive and physical performance of karate athletes

Introduction: It has been established that napping or listening to motivational music during warm-up is an effective strategy to enhance cognitive and physical performances. However, which could provide better enhancement warrants further investigation. This study aimed to examine the effect of a 30-min nap opportunity (N30), a warm-up with self-selected motivational music (WUMM), and the combination of N30 with WUMM (WUMM + N30) on cognitive and physical performances in karate athletes. Method: In a randomized order, 14 national-level male karate athletes performed four experimental sessions: control, N30, WUMM, and WUMM + N30. Simple (SRT) and choice (CRT) reaction times, selective attention, subjective sleepiness (ESS), mood state (POMS), countermovement jump (CMJ), and karate agility test (KAT) were evaluated before and after an all-out exhaustive task [i.e., the Karate Specific Test (KST)]. Ratings of perceived exertion (RPE) were measured immediately after the KST. Results: Compared to the control, all interventions improved cognitive outcomes, mood, and sleepiness. No effects on physical performances (CMJ and KAT) were found after N30. Compared to N30, WUMM + N30 improved SRT pre- and post-exercise (pre: p < 0.05, d = 0.72; post: p < 0.001, d = 0.14), CRT (pre: p < 0.001, d = 0.07; post: p < 0.001, d = 0.10), attention (pre: p < 0.05, d = 0.06; post: p < 0.01, d = 0.06), mood (pre: p < 0.001, d = 2.53; post: p < 0.001, d = 0.23), and decreased ESS scores (pre: p < 0.01, d = 1.41; post: p < 0.05, d = 1.18). However, there was no significant difference between WUMM and N30. KST performance was not affected by the experimental conditions. However, the KST-induced performance deficit in CMJ and KAT was smaller following WUMM + N30 compared to WUMM and N30. RPE scores were lower following WUMM + N30 and WUMM. Conclusion: These findings suggest that a combination of listening to self-selected motivational music during warm-up with a 30-min nap could be an effective strategy to enhance cognitive and physical performance decline caused by fatigue induced by exercise.

Physiological response and physical performance after 40 min and 90 min daytime nap opportunities

This study aimed to examine the impact of 40-min and 90-min naps on performance in the 5-m shuttle run test (5mSRT) and on various physiological and perceptual measures. Sixteen male athletes (20 ± 3 years, 173 ± 7 cm, 67 ± 7 kg) performed the 5mSRT after a 40-min nap (N40), after a 90-min nap (N90), and in a no-nap, control condition (N0). The 5mSRT involves six repetitions of 30 s of all-out exercise. Total distance (in the six repetitions) and highest distance (in a single repetition) in the 5mSRT were greater after naps than in N0 (p < 0.001), and the total distance, which reflects the anaerobic capacity, was greater in N90 than in N40 (p < 0.05). Physiological and perceptual responses were favourable in both nap conditions (p < 0.01), more so in N90 than in N40 (p < 0.05). Together, the results support the contention that physiological/perceptual responses after napping contribute to improved exercise performance and that longer naps are more effective.

Is daytime napping an effective strategy to improve sport-related cognitive and physical performance and reduce fatigue? A systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To estimate the association between daytime napping and cognitive and physical sport performance and fatigue after normal sleep and partial sleep deprivation (less sleep duration than necessary).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

The PubMed, Scopus, Web of Science, Cochrane Central, SportDiscus and PsycINFO databases.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials on the effect of daytime napping on sport performance and fatigue available from inception to 2 December 2022. Standardised mean differences (SMD) and their 95% compatibility intervals (CI) were estimated with the DerSimonian-Laird method through random effect models.

RESULTS

In the 22 included trials, 291 male participants (164 trained athletes and 127 physically active adults) aged between 18 and 35 years were studied. When performed after a normal night of sleep, napping from 12:30 hours to 16:50 hours (with 14:00 hours being the most frequent time) improved cognitive (SMD=0.69, 95% CI: 0.37 to 1.00; I²=71.5%) and physical performance (SMD=0.99, 95% CI: 0.67 to 1.31; I²=89.1%) and reduced the perception of fatigue (SMD=-0.76, 95% CI: -1.24 to -0.28; I²=89.5%). The positive effects of napping were also confirmed after partial sleep deprivation. Overall, the benefits were higher with a nap duration between 30 and <60 min and when the time from nap awakening to test was greater than 1 hour.

CONCLUSIONS

After a night of normal sleep or partial sleep deprivation, a daytime nap between 30 and <60 min has a moderate-to-high effect on the improvement of cognitive performance and physical performance and on the reduction of perceived fatigue.

PROSPERO REGISTRATION NUMBER

CRD42020212272.

Longitudinal associations between daytime napping and cognitive function in Chinese older adults

BACKGROUND

Little was known about the longitudinal associations between daytime napping and cognitive function in China. Thus, the study aimed to explore the cross-sectional and the longitudinal relationship between daytime napping and cognitive performance in the elderly Chinese population.

METHODS

The data was from the China Health and Retirement Longitudinal Study (CHARLS). Daytime napping was self-reported. Cognitive function was assessed via a structured questionnaire in two dimensions: episodic memory and mental status. Linear regression and mixed-effect model were applied to explore the association between daytime napping and cognitive function.

RESULTS

A total of 2,875 and 2,440 participants aged over 65 years were included in the cross-sectional and the longitudinal studies, respectively. In the cross-sectional study, non-nappers and extended nappers had significantly lower global cognition scores (P<0.01), as well as significantly lower scores for episodic memory (P<0.05) and mental status (P<0.01), compared with moderate nappers. In the longitudinal analysis, no napping and extended napping were significantly associated with global cognitive decline (P<0.05) and only extended napping showed the significant association for the decline in episodic memory as well as mental status (P<0.01).

LIMITATIONS

Daytime napping duration was self-reported by participants.

CONCLUSION

The study found a longitudinal association between extended napping duration and worse cognitive function.

A systematic review of effects of daytime napping strategies on sports performance in physically active individuals with and without partial-sleep deprivation

Background

Sleep is the body's natural recovery process, restoring routine metabolic and regulatory functions. Various sleep interventions have been developed to facilitate recovery, and athletic performance, and daytime napping are among them. However, due to inconsistencies in studies, it remains unclear whether daytime napping affects sports performance. This article aims to review the effects of daytime napping on various variables of sports performance in physically active individuals with and without partial-sleep deprivation.

Methods

A systematic search in three clinical databases, namely Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, and Web of Science, was conducted. To be included in the current review, the study should be a randomized controlled trial that evaluated the influence of daytime napping on one or more components of sports performance in healthy adults, 18 years old or older.

Results

In the accessible data available until December 2021, 1,094 records were found, of which 12 relevant randomized controlled trials were selected for qualitative synthesis. The majority of studies reported favourable effects of daytime napping on sports performance. However, only one study reported no significant impact, possibly due to a different methodological approach and a shorter nap duration.

Conclusion

Napping strategies optimize sports performance in physically active, athletic populations, benefitting partially sleep-deprived and well-slept individuals, with longer nap durations (~90 min) having more significant advantages. Daytime naps can be considered as cost-efficient, self-administered methods promoting recovery of body functions.

Duration of Daytime Napping Is Related to Physical Fitness among Chinese University Students

Reportedly, daytime napping affects the physical fitness of athletes. However, results of these studies are conflicting, and may not be generalizable to all populations. Early adulthood is an important period linking adolescents and adults, during which building good physical fitness is crucial for their remaining lives. Thus, we investigated whether daytime napping duration is associated with physical fitness among Chinese university students. This study was based on an annual physical health examination for all university students and included 11,199 participants (6690 males; 4509 females). The daytime napping duration was assessed using a self-report questionnaire. Physical fitness was measured with a 50 m sprint; 1000 m (for males) and 800 m (for females) runs; standing long jump, sit-and-reach, pull-up (for males), and sit-up (for females) tests; and vital capacity. The adjusted association was evaluated using analysis of covariance. Of the participants, 86% napped regularly. After covariate adjustment was performed, significant V-shaped associations were observed between the daytime napping duration and the 50 m sprint and 800 m run results in males and females. Inverted V-shaped associations were observed between the daytime napping duration and the sit-and-reach, standing long jump, and pull-up test performances and vital capacity in males and between the daytime napping duration and the standing long jump test performance in females. Daytime napping for <30 min may have beneficial effects on physical fitness among university students.

A Thirty-Minute Nap Enhances Performance in Running-Based Anaerobic Sprint Tests during and after Ramadan Observance

The purpose of this study was to determine the impact of a 30 min nap (N30) on the Running-Based Anaerobic Sprint Test (RAST) both during and after Ramadan. Ten physically active kickboxers (age: 21.20 ± 1.61 years, height: 174.80 ± 4.34 cm, body mass: 73.30 ± 7.10 kg and body mass index (BMI): 24.00 ± 2.21 kg/m²) voluntarily performed the RAST test after an N30 and in a no-nap condition (NN) during two experimental periods: the last ten days of Ramadan (DR) and ∼3 weeks after Ramadan (AR). During each DR-NN, DR-N30, AR-NN and AR-N30 protocol, kickboxers performed RAST performance. A statistically significant difference was found between Ramadan periods (DR vs. AR) in terms of max power (W) (F = 80.93; p₁ < 0.001; η²_p = 0.89), minimum power (W) (F = 49.05; p₁ < 0.001; η²_p = 0.84), average power (W) (F = 83.79; p₁ < 0.001; η²_p = 0.90) and fatigue index (%) results (F = 11.25; p₁ = 0.008; η²_p = 0.55). In addition, the nap factor was statistically significant in terms of the max power (W) (F = 81.89; p₂ < 0.001; η²_p = 0.90), minimum power (W) (F = 80.37; p₂ < 0.001; η²_p = 0.89), average power (W) (F = 108.41; p₂ < 0.001; η²_p = 0.92) and fatigue index (%) results (F = 16.14; p₂ = 0.003; η²_p = 0.64). Taking a daytime nap benefits subsequent performance in RAST. The benefits of napping were greater after an N30 opportunity for DR and AR.

Effect of sleep and fatigue on cardiovascular performance in young, healthy subjects

Physical performance could be negatively affected by sleep deficiency and fatigue. The present study assesses the role of sleep quality, fatigue and motivation on cardiovascular performance (VO₂peak, Wmax, and HRmax) in a sample of active young subjects. The current study is a cross-sectional design. Ninety-six university students (males 54.2%; 21.5 ± 2.9 yrs) completed an incremental exercise test on a bicycle ergometer. Sleep, fatigue, and motivation were assessed with the Pittsburgh Sleep Quality Index and two visual analogue scales, respectively. Differences in VO₂peak, Wmax, HRmax, self-perceived fatigue and motivation were compared between good and bad sleepers and sleep duration >/<7.5 h, while regression analysis defined the predictors of VO₂peak, Wmax, and HRmax_. In the male sample, good and bad sleepers' differences were significant only for self-perceived fatigue (p = 0.04). The female sample showed no statistically significant differences between good and bad sleepers and different sleep durations. In the male sample, linear regression analysis showed a significant inverse correlation between Wmax and the PSQI score (-0.4, p = 0.004). The stepwise regression model indicated that sleep (β = -0.3, p = 0.02) was a significant predictor of VO₂peak in males accounting for 20% of the variance, whereas physical performance seems more affected by fatigue (β = -0.4, p = 0.03) in females. In conclusion, chronic inadequate and self-reported sleep quality seems to be one of the factors compromising cardiovascular performance in males.

Effects of an afternoon nap on sustained attention and working memory: The role of physiological arousal and sleep variables

Taking a short midday nap has been associated with higher alertness and better cognitive task performance. Yet, the mechanisms associated with nap-dependent performance enhancement are unclear. The current study was conducted to explore the impact of physiological arousal during cognitive task and sleep architecture during a pre-task nap on post-nap behavioral outcomes. A within-subjects design (N = 18) was employed, in which participants either took a nap or remained awake for 40 min during the post-lunch period. The psychomotor vigilance test (PVT) and n-back task were administered to assess sustained attention and working memory, respectively, with each task including one block of easy trials and one block of difficult trials. Results showed that a short midday nap improved sustained attention but not working memory. In addition, a midday nap induced lower physiological arousal during the performance on both cognitive tasks, with relatively higher delta and lower beta activity. The relative power of theta and alpha were positively correlated with performance on the easy PVT, whereas the alpha power was negatively correlated with performance on the difficult PVT, and the theta power was negatively correlated with reaction speed in the n-back task regardless of the task difficulty. Meanwhile, the shorter total sleep time and longer time of wake after sleep onset were associated with the faster overall reaction speed in PVT easy trials. These findings suggested that both changes in physiological arousal and sleep variables might account for changes in task performance after a short midday nap.

Planning Ability and Alertness After Nap Deprivation: Beneficial Effects of Acute Moderate-Intensity Aerobic Exercise Greater Than Sitting Naps

Nap deprivation is regarded as a sleep loss for habitual nappers. The beneficial effects of napping and moderate-intensity aerobic exercise on the reduction in planning ability following nighttime sleep deprivation have been proven. However, it is still unknown whether it can improve the performance decline caused by daytime nap deprivation in habitual nappers. Seventy-four healthy adults who had a long-term habit of taking naps were assigned to three interventions after receiving nap deprivation: (1) Control group (no intervention); (2) Nap group (15-min sitting naps); (3) Exercise group (15-min aerobic exercise), in which subjective alertness, mood, fatigue, and task performance in objective alertness (Psychomotor Vigilance Task, PVT) and planning ability (the Tower of London Task) were measured. Results showed that nap deprivation negatively influenced some performance on the psychomotor vigilance (i.e., response times and 10% slowest response time) and planning ability (i.e., planning time). And acute moderate-intensity aerobic exercise improved psychomotor alertness (i.e., response times) and planning ability (i.e., execution accuracy, execution time), a 15-min sitting naps only alleviated subjective fatigue, whereas some performance (i.e., response times) deteriorated when no intervention was used. These findings suggested that acute moderate-intensity aerobic exercise has a better restorative effect on the reduced planning ability and objective alertness due to nap deprivation compared to sitting naps.

Evaluation on the automotive skill competency test through 'discontinuity' model and the competency test management of vocational education school in Central Java, Indonesia

This article provides an alternative competency test model for vocational education schools in Central Java, Indonesia which particularly for automotive skill competency in order to replace the current competency test model that has been implemented for several decades which the author's concern about the students' accomplishment during the competency test, aimed to improve competency test results to increase the students' job opportunity in the labor market. Currently, the applied competency test model is the ‘Continuity’ model, where the students are given five tasks and should be finished within five hours with limited break time. This model tends to increase students' fatigue and stress levels. Consequently, the students lose their focus and concentration which adversely impacts their competency test results. In this study, the new competency test model namely the ‘Discontinuity’ competency test model was proposed aiming to overcome the issue of the ‘Continuity’ model. To research the effect of the ‘Discontinuity’ model implementation on the students' competency test results and vocational school competency test management, a study was done among 100 students and 50 teachers in 10 vocational education schools around Central Java, Indonesia. The results show that the ‘Discontinuity’ competency test model gives a significant improvement in the students' competency test scores. This reasonably happened due to the implementation of the ‘Discontinuity’ model gives the students time to break for an hour of each competency task. Without this break time, fatigue and stress levels of the students will significantly increase which adversely affect the students' competency final score. In addition, the new management of the competency test was proposed in this research.

Longer Nap Duration During Ramadan Observance Positively Impacts 5-m Shuttle Run Test Performance Performed in the Afternoon

It is well-documented that changes in the rhythm of life during Ramadan affect sleep schedules (i.e., interruption of night sleep patterns) and are likely to have negative effects on physical and cognitive performances. The aim of the present study was to examine the effect of different naps opportunities’ durations during Ramadan on performance of short-duration repetitive maximal exercise and perception of effort. Fifteen physically active men (age: 21 ± 3 years, height: 177 ± 6 cm, body-mass: 73 ± 10 kg) performed a 6 × 30-s shuttle run test after a 25-min nap (N25), a 45-min nap (N45), and in a no-nap condition (NN) during three experimental periods: ∼2 weeks before Ramadan (BR), the last ten days of Ramadan (ER), and ∼3 weeks after Ramadan (AR). During the shuttle run test performed in the late afternoon, the greatest distance (GD), the total distance (TD) and a fatigue index (FI) were assessed. Rating of perceived exertion (RPE) was determined after each 30-s effort. Dietary intake and sleep quality were assessed in each of the three periods. Compared to BR, GD and TD were lower in the ER testing period (p = 0.005; d = 0.54) but returned to BR levels in the AR period. During ER, carbohydrate intake was lower (p = 0.04; d = 0.2), and sleep duration and sleep quality were reduced (d = 0.27 and 0.54, respectively), although other aspects of dietary intake and sleep pattern were not affected. Compared to NN, GD and TD were higher after N25 (d = 0.57 and 0.34, respectively) and N45 (d = 0.93 and 0.88 respectively). RPE was lower in N45 (p = 0.035, d = 0.84). N45 resulted in higher TD (p = 0.021, d = 0.13) and lower RPE (p = 0.004; d = 0.57) compared to N25 during ER. Taking a daytime nap benefits subsequent performance in a shuttle run test, whether sleep the previous night was normal (as in BR) or compromised (as in ER). The benefits of napping were greater after a 45-min nap opportunity than after a 25-min nap opportunity.

Structural Model of Napping Motivation Among Chinese College Students Based on Self-Rating: Evidence from an Exploratory Factor Analysis

PURPOSE

Previous epidemiological and psychological studies have assessed the effects of napping on individual performance and health. However, these studies did not distinguish between spontaneous and passive napping due to sleep disorders. Therefore, this study aimed to explore the potential motivation for napping among Chinese college students and to assess the relationship between different nap motivations and sleep.

PATIENTS AND METHODS

This cross-sectional study was conducted at a university in Shanghai in March 2021 using convenience sampling. A total of 564 Chinese college students with self-reported napping habits participated in this study. Exploratory factor analysis (EFA) was employed to analyze 34 self-rated motivations for napping to derive a potential structural model of napping motivation. Correlation and multiple linear regression analyses were performed to determine the influence of nap motivation on sleep behavior.

RESULTS

Chinese college students mainly take naps to reduce fatigue, usually in the form of frequent and long naps (6.25 ± 1.24 days; 64.62 ± 23.70 min). A structural model of nap motivation named the I-DREAM model was proposed, consisting of six factors: restorative, induced, mindful, appetitive, dysregulative, and exercise naps. There were also sex differences in nap motivation, as women preferred restorative naps and appetitive naps, while men preferred exercise naps (p < 0.01, p < 0.05). Furthermore, there was a significant correlation between nap motivation on nap duration, frequency and nighttime sleep quality (R² = 2.70-18.9%).

CONCLUSION

The proposed I-DREAM model implies that there are population differences in napping motivation. Different motivations also have different relationships with napping patterns and nighttime sleep. In understanding the relationship between naps and health status, nap motivation may be an extremely important influencing factor.

Performance, muscle damage, and inflammatory responses to repeated high-intensity exercise following a 40-min nap

The purpose of this study was to examine the effect of a 40-min nap opportunity (N40) on performance during, markers of muscle damage and inflammation, and the perception of fatigue and recovery, in response to a 5-m shuttle run test (5msrt). Fifteen male amateur athletes performed the 5msrt under two conditions: N40 and no-nap condition (NN). Blood biomarkers were collected at rest and after the 5msrt to measure muscle damage (i.e., creatinine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (ASAT), and alanine aminotransferase (ALAT)) and inflammation (i.e., C-reactive protein (CRP)). RPE was determined immediately after each repetition of the test and PRS and DOMS were determined 5 min, thereafter. Compared to NN, N40 improved the highest distance (p<0.001, Δ=+7.9%) and the total distance (p<0.001, Δ=+7.2%) attained during the 5msrt. Pre and post the 5msrt, participants presented lower muscle damage (i.e., CK, LDH, ASAT and ALAT) and inflammation (i.e., CRP) (p<0.05) values in the N40 compared to NN. Concerning RPE, DOMS, and PRS, there was a positive effect in the N40 vs. NN (p<0.01). N40 represents an effective method for improving repeated high intensity short-term maximal performance, PRS, and associated muscle damage and inflammation, and reducing RPE and DOMS.

The impact of daytime napping on athletic performance - A narrative review

Mid-day napping has been recommended as a countermeasure against sleep debt and an effective method for recovery, regardless of nocturnal sleep duration. Herein, we summarize the available evidence regarding the influence of napping on exercise and cognitive performance as well as the effects of napping on athletes' perceptual responses prior to or during exercise. The existing studies investigating the influence of napping on athletic performance have revealed equivocal results. Prevailing findings indicate that following a normal sleep night or after a night of sleep loss, a mid-day nap may enhance or restore several exercise and cognitive performance aspects, while concomitantly provide benefits on athletes' perceptual responses. Most, but not all, findings suggest that compared to short-term naps (20-30 min), long-term ones (>35-90 min) appear to provide superior benefits to the athletes. The underlying mechanisms behind athletic performance enhancement following a night of normal sleep or the restoration after a night of sleep loss are not clear yet. However, the absence of benefits or even the deterioration of performance following napping in some studies is likely the result of sleep inertia. The present review sheds light on the predisposing factors that influence the post-nap outcome, such as nocturnal sleep time, mid-day nap duration and the time elapsed between the end of napping and the subsequent testing, discusses practical solutions and stimulates further research on this area.

Does Bright Light Counteract the Post-lunch Dip in Subjective States and Cognitive Performance Among Undergraduate Students?

The post-lunch dip in alertness and performance was widely experienced during the early afternoon. Taking a short nap was documented as a practical strategy for habitual nappers to counteract the decline of alertness and performance. Yet, it remains unknown whether bright light exposure in the early afternoon working hours could alleviate the performance deficits caused by a post-lunch nap loss for habitual nappers. Seventeen undergraduate students who had a long-term habit of taking a post-lunch nap were assigned to three interventions: (1) a short nap + normal indoor light (100 lx, 4,000 K at eye level); (2) no nap + normal indoor light, and (3) no nap + blue-enriched bright light (1,000 lx, 6,500 K at eye level), in which subjective alertness (Karolinska Sleepiness Scale, KSS), mood (Positive and Negative Affect Schedule, PANAS), and task performance in sustained attention (psychomotor vigilance test, PVT), response inhibition (go/no-go task), and working memory (paced visual serial addition test, PVSAT) were measured. Results showed that a post-lunch nap deprivation significantly increased subjective sleepiness and negative mood and impaired performance in PVT and PVSAT, while exposure to bright blue-enriched white light vs. normal indoor light in the early afternoon significantly relieved such negative effects on mood, sleepiness, and performance in PVSAT; subjective positive mood and performance in PVT and go/no-go task remained unaffected with light intervention. These findings suggested that bright blue-enriched white light exposure could be a potential strategy for those who are suffering from drowsiness and low working memory following a habitual midday nap loss.

Benefits of Daytime Napping Opportunity on Physical and Cognitive Performances in Physically Active Participants: A Systematic Review

BACKGROUND

Evidence suggests that athletes often experience chronic sleep disturbance. Napping is widely recommended as a safe and non-invasive intervention to counteract the negative effects of partial sleep deprivation. However, systematic reviews on the benefits of napping have yet to be undertaken.

OBJECTIVE

(i) To evaluate the effectiveness of diurnal napping opportunities on athletes' physical and cognitive performance and (ii) to outline how aspects of the study design (i.e., nap duration, exercise protocol, participants' fitness level and previous sleep quantity) can influence the potential effects of napping through a systematic appraisal of the literature.

METHODS

This systematic review was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. PubMed, Web of Science and SCOPUS databases were searched up to June 2020 for relevant studies investigating the effect of napping on physical and cognitive performances in physically active participants. Fourteen strong-quality and four moderate-quality (mean QualSyst score = 75.75 ± 5.7%) studies met our inclusion criteria and were included in the final sample (total participants: 158 physically active and 168 athletes).

RESULTS

Most studies (n = 15) confirmed the beneficial effects of napping and showed that diurnal napping improved short-term physical performance (n = 10), endurance performance (n = 3) and specific skills performance (n = 2). Two studies showed no significant napping effect and only one study showed reduced sprint performance following diurnal napping. Moreover, napping improved reaction time (n = 3), attention (n = 2) and short-term memory (n = 1) performances. Importantly, "replacement naps" improved both physical and cognitive performance regardless of the type of exercise. However, "prophylactic naps" improved only jump, strength, running repeated-sprint, attention and reaction time performances. In addition, this systematic review revealed that longer nap opportunities (i.e., 90 min) resulted in better improvement of physical and cognitive performance and lower induced fatigue.

CONCLUSIONS

A diurnal nap seems to be an advantageous intervention to enhance recovery process and counteract the negative effect of partial sleep deprivation on physical and cognitive performance. Particularly, to optimize physical performances of athletes experiencing chronic lack of sleep, findings from the included individual studies suggest 90 min as the optimal nap duration. Diurnal napping may be beneficial for athletes but this benefit should be viewed with caution due to the quality of the evidence, risk of bias and the limited evidence about napping interventions.

A daytime 40-min nap opportunity after a simulated late evening soccer match reduces the perception of fatigue and improves 5-m shuttle run performance

The effect of a 40-min nap opportunity was investigated during the day following a late evening simulated soccer match. Twelve male amateur soccer players (23 ± 3 years; 77.3 ± 5.3 kg; 1.76 ± 0.04 m) performed the Loughborough-intermittent-shuttle test at 21h00 and the following day they completed the sleepiness scale after either a nonap (N0) or 40-min nap (N40) opportunity that began at 14h00. At 17h00, participants performed the 5-m shuttle run test (5mSRT) (6 × 30-s with 35-s in-between; best distance (BD) and total distance (TD) were calculated). After performing the 5mSRT, they provided their rating of the perceived exertion (RPE) and rated their muscle soreness. Sleepiness scores were significantly lower in N40 in comparison with N0 (P < 0.05). A significant increase of TD (+64.5 m) and BD (+9.6 m) after N40 compared to N0 was observed (P < 0.05). The improved performance was associated with reduced levels of muscle soreness and lower RPE. In conclusion, a daytime 40-min nap opportunity after a late evening simulated soccer match improves short-term repetitive maximal performance in soccer players, and has positive effects on perception of sleepiness, muscle soreness, and RPE.

Association between daytime napping and stroke: A dose-response meta-analysis

Daytime napping is common in many regions around the world and has been an important part of people's daily life. Daytime napping has attracted increasing attention in recent years. Thus, we conducted a meta-analysis to evaluate the relationship between daytime napping and stroke, and help reduce the risk of stroke by improving living habits. The Embase, PubMed, Web of Science and PsycINFO databases were searched for cohort studies published before October 2020 and eight eligible studies with 524,408 participants and 5,875 stroke cases were included in the final analysis. The pooled relative risk (RR) of stroke was 1.47 (95% confidence interval [CI]: 1.24-1.74; p < .001) with significant heterogeneity (I²  = 58%, p for heterogeneity = 0.02). However, the heterogeneity decreased when the study in which adjusting for sleep duration and stratifying the results based on sleep duration was not performed was excluded (RR: 1.38; 95% CI: 1.19-1.60, I²  = 44%, p for heterogeneity = 0.10). In dose-response analysis, the linear trend indicated that for every 10-min increase in daytime napping, the risk of stroke increased by 3%. Further well-designed large studies are needed to explore the effects of daytime napping on stroke and the underlying biological mechanisms.

Does warming up with different music tempos affect physical and psychological responses? The evidence from a chronobiological study

BACKGROUND

This study examined the effects of listening to different music tempos during warm-up on short-term maximal performance and psychological responses, as a function of Times of Day (TOD).

METHODS

Fifteen well trained subjects (93.75% were semi-professional soccer players) randomly performed the 30-s Continuous Jump test (CJ30) during three morning sessions (07h00) and three evening sessions (17h00), separated by 48h of recovery, each after a warmup under three different conditions: without music (NO-M), with music at 60 bpm (LOW-M), and with music at 120-140 bpm (HIGH-M). The maximal jump height (Hmax), mean jump height of all jumps (Hmean), and fatigue index (FI %) were measured during CJ30. Feeling states (FS) were determined after warm-up, and body temperature was controlled before/after warm-up, as well as after CJ30.

RESULTS

Data analysis showed that Hmax, Hmean, and body temperature were higher at 17h00 than 07h00 in all experimental conditions. Moreover, Hmax, Hmean and FS were better after warm-ups with LOW-M and HIGH-M compared to NO-M condition at both TOD, with a higher gain at 07h00. More importantly, Hmax, Hmean and FS were better after warm-up with HIGH-M than with LOW-M at both TOD, with a higher gain at 07h00.

CONCLUSIONS

Although both music tempos were beneficial, warming-up with high music tempo (120-140 bpm) is better than warming-up with low music tempo (60 bpm) for improving short-term maximal performance and psychological responses whatever the TOD, especially in the morning hours.

My job impacts my sleep: signs and symptoms of insomnia among healthcare workers

Potential insomnia in healthcare workers is a public health concern as it may degrade the quality of patient care. We examined the prevalence of insomnia symptoms in healthcare workers and their perceived need for a sleep intervention. Participants were 62 nurses working full-time at a U.S. hospital. These nurses were asked about background characteristics, perceived stress, sleep concerns, and need for a sleep intervention. They also participated in 14-d ecological momentary assessment (EMA) and actigraphy sleep study. A qualitative analysis showed that the majority (92%) of participants reported at least one sleep concern with insomnia-related concerns being most prevalent (68%). Quantitative analyses indicated that those with insomnia-related concerns had higher perceived stress overall and lower EMA sleep sufficiency and sleep quality. Moreover, participants with insomnia concerns had shorter actigraphy-measured nap duration prior to non-workdays than those without. Nearly all (95%) expressed interest in participating in a sleep intervention; an online format and mindfulness contents were most preferred. Our results suggest a high prevalence of insomnia symptoms and a high interest in a sleep intervention in nurses. Information obtained from this study could be used to deliver a tailored sleep intervention for nurses whose role in public health is essential.

Exergaming and Aquatic Exercises Affect Lung Function and Weight Loss in Obese Children

We investigated the effect of exergames and aquatic exercises on lung function and weight loss in obese children. Sixty-one obese male primary-school children were randomly allocated to video game, aquatic exercise, and control groups. Lung functions and anthropometric variables were measured before and after the intervention and after one month (follow-up). In the video game group, an Xbox Kinect game was played for 60 min during three sessions a week. The aquatic aerobic exercise was performed three times per week and consisted of a warm-up, main exercises, and a cool down phase. For the video game group, there was a significant reduction in body weight between (i) pre- and (ii) post-intervention and follow-up. In the aquatic exercise group, there was a significant reduction in body weight between pre- and post-intervention and between pre-intervention and follow-up. Both exercise groups improved the waist/hip ratio index compared to the control group. Forced vital capacity was significantly improved in the follow-up of the video game group and the aquatic exercise group compared to the control group. A significant improvement was found in forced expiratory volume in the first second at post-intervention and follow-up in the video game and the aquatic exercise groups. Exergames and aquatic exercises improved weight loss and lung function in obese children.

Effects of a 30 min nap opportunity on cognitive and short-duration high-intensity performances and mood states after a partial sleep deprivation night

This study evaluated the effects of partial-sleep-deprivation (SDN) and a 30 min nap opportunity on physical and cognitive performances and mood states. Fourteen physically active students (BMI = 232.8 ± 0.4 kg/m²) performed the reaction time, the number cancellation (i.e., assessing vigilance) and the 5-m shuttle run tests and responded to the Profile of Mood States (POMS-f) questionnaire at 18h00 after a normal-sleep (NSN) and a SDN) and after two nap conditions (Nap and no-Nap) realized between 13h00 and 13h30. Vigilance and the reaction time were better after Nap compared to no-Nap opportunity following NSN and SDN and during NSN compared to SDN only during no-Nap. Total and peak distance during the 5-m shuttle run test were higher and the fatigue index was lower during Nap compared to no-Nap condition after NSN and SDN and during NSN compared to SDN during Nap and no-Nnap. Anxiety, fatigue, confusion, and depression were lower and vigour was higher during Nap compared to no-Nap after NSN and SDN and during NSN compared to SDN during Nap and no-Nap. In conclusion, a 30-min of nap opportunity helps to overcome the negative effect of SDN on mood states as well as physical and cognitive performances.

A Thirty-Five-Minute Nap Improves Performance and Attention in the 5-m Shuttle Run Test during and Outside Ramadan Observance

Ramadan observance is characterized by several changes in behaviors, such as food and sleep, which could affect physical and cognitive performance. The aim of the present study was to investigate the effects of a 35-min nap (N35) opportunity on physical performance during the 5-m shuttle run test (5mSRT); attention; feelings; mood states; and perceptual measures of stress, fatigue, and muscle soreness during Ramadan observance. Fourteen physically active men (22 ± 3 years, 177 ± 4 cm, 76 ± 5 kg) were tested after a no-nap condition (N0), N35 15 days before Ramadan (BR), the last 10 days of Ramadan (DR), and 20 days after Ramadan (AR). Measures included the digit cancellation test (attention estimation), the profile of mood state (POMS), and the Hooper questionnaires. After a 5-min standard warm-up, participants performed the 5mSRT (6 × 30 s with 35 s in between; best distance (BD), total distance (TD), and fatigue index (FI) were recorded), along with the rating of perceived exertion (RPE) after each test repetition. After the 5mSRT test, participants responded to the feeling scale (FS). The results showed that TD and FI during the 5mSRT were not affected by Ramadan observance. However, BD was significantly lower than DR compared to AR after N0 (∆ = -4.3 ± 1.3%; p < 0.01) and N35 (∆ = -2.6 ± 1.0%; p < 0.05). After N0, attention decreased significantly at DR in comparison with BR (p < 0.05) and AR (p < 0.001). BD and TD improved after N35 compared to N0 at BR (∆ = +4.4 ± 2.1%, p < 0.05 for BD and ∆ = +4.8 ± 1.6%, p < 0.01 for TD), DR (∆ = +7.1 ± 2.2%, p < 0.05 for BD and ∆ = +5.1 ± 1.6%, p < 0.01 for TD), and AR (∆ = +5.5 ± 1.5%, p < 0.01 for BD and ∆ = +5.2 ± 1.2%, p < 0.001 for TD). A significant increase in attention was observed after N35 in comparison with N0 at DR (p < 0.01) and AR (p < 0.01). However, no changes were found for the perception of mood states, stress, sleep, muscle soreness, and the FI during the 5mSRT. Also, N35 was better than N0 for RPE at DR (p < 0.05), feelings at AR (p < 0.05), and fatigue estimation at AR (p < 0.01). A 35-min nap opportunity may have beneficial effects on physical and cognitive performances before, during, and after Ramadan.

Effects of a 20-min Nap after Sleep Deprivation on Brain Activity and Soccer Performance

We examined effects of a 20-min nap following 3 h of sleep deprivation on brain wave activity, auditory reaction time, the running-based anaerobic sprint test, leg muscle strength and the rating of perceived exertion in male college soccer players. Eleven players underwent three sleep conditions; normal sleep, sleep deprivation and 20-min nap after sleep deprivation. The sleep deprivation demonstrated an increase in the mean power of delta waves over the frontal area and a decrease in the mean power of alpha waves over the parietal area compared to the normal sleep. The nap and the sleep deprivation showed an increase in auditory reaction time compared with those in the normal sleep. The sleep deprivation demonstrated a decrease in the running-based anaerobic sprint test compared to the normal sleep, whereas the nap has partially reversed only minimal power and average power of the running-based anaerobic sprint test. The nap showed a recovery effect on leg muscle strength, but not on the rating of perceived exertion compared with the sleep deprivation. Thus, a 20-min nap after sleep deprivation did not completely return brain activity back to active state and did not entirely reverse the negative impact of sleep deprivation on soccer performance in soccer players.

A 90 min Daytime Nap Opportunity Is Better Than 40 min for Cognitive and Physical Performance

This study examined the effects of different nap durations on attention and physical performance as well as mood states, sleepiness, perceived exertion (RPE), recovery (PRS), and muscle soreness (DOMS) in trained men. Fourteen amateur team sport players (age: 20.3 ± 3.0 years, height: 173.1 ± 6.7 cm, body-mass: 68.1 ± 6.6 kg) performed a maximal voluntary isometric contraction (MVIC) test, 5-m shuttle run, and the digit-cancellation (i.e., attention) test after a no-nap (N0) and 40-min (N40) and 90-min (N90) of nap opportunities. Subjective measurement of mood states, RPE, PRS and DOMS were determined. Compared to N0, both nap durations enhanced attention, MVIC, total distance (TD), and higher distance (HD) (p < 0.001), with a higher gain after N90 compared to N40 for attention (Δ = +3), MVIC (Δ = +30 N) and TD (Δ = +35 m) (p < 0.001). Total mood scores were better after N40 and N90 compared to N0 (p < 0.05), with lower scores after N90 compared to N40 (p < 0.05). DOMS and RPE scores were significantly lower and PRS was significantly higher after N40 and N90 compared to N0 and after N90 compared to N40 (p < 0.05). Although both nap opportunity durations were beneficial, N90 was better than N40 for improving physical performances and attention as well as the perception of recovery, reducing fatigue perception, muscle soreness, and negative mood states.

Effects of 25-Min Nap Opportunity during Ramadan Observance on the 5-m Shuttle Run Performance and the Perception of Fatigue in Physically Active Men

We aimed to investigate the effects of a 25-min nap opportunity on physical performance during the 5-m shuttle run test (5mSRT), feelings (i.e., evaluated by the feeling scale), attention (i.e., evaluated by the digit cancellation test) and the perception of fatigue (i.e., recorded by the rating of perceived exertion (RPE)) during Ramadan observance. Twelve physically active men (age: 21.1 ± 3.2 yrs, height: 1.76 ± 0.05 m, body-mass: 71.2 ± 9.3 kg) voluntarily participated in five test sessions: 15 days before Ramadan (BR), the first 10 days of Ramadan (FR), the last 10 days of Ramadan (ER), 10 days after Ramadan (10AR) and 20 days after Ramadan (20AR). During each test session, participants performed the digit cancellation test, a 5-min standard warm-up, the 5mSRT (6 × 30-s with 35-s intervals-between) and the rating of perceived exertion (RPE) after no-nap (N0) and 25-min nap opportunity (N25) conditions. Participants also completed the Pittsburgh Sleep Quality Index (PSQI) during each period. The total distance covered during the 5mSRT did not differ significantly before, during or after Ramadan, but was significantly greater after N25 compared to N0 at 10AR (687.5 ± 23.0 m vs. 725.6 ± 41.1 m; p = 0.018) and 20AR (698.3 ± 19.8 m vs. 742.6 ± 58.3 m; p = 0.003). The attention scores were higher after N25 in comparison with N0 at 10AR (p = 0.04) and 20AR (p = 0.02). RPE scores were not significantly different between N25 and N0 conditions. Feelings scores were higher after N25 compared to N0 during both FR (p = 0.007) and 20AR (p = 0.04). A significant deterioration of sleep quality was recorded during Ramadan (i.e., PSQI scores were significantly higher during and after compared to BR (p < 0.0005)). A 25-min nap opportunity was beneficial for physical and cognitive performance after Ramadan observance; however, any effect is insufficient to show significant beneficial impacts during Ramadan.

Effect of Angle of View and Partial Sleep Deprivation on Distance Perception

The present study aimed to investigate the effects of intensive effort on egocentric distance perception according to different angles of view after sleep deprivation at the beginning (SDB) or at the end (SDE) of the night and after a normal sleep night (NNS). Ten male students soccer players (age 22.8 ± 1.3 years; body mass 72.0 ± 10.4 kg; body height 180.0 ± 3.0 cm) performed a repeated cycling (RS) exercise (10 × 6 s maximal cycling with 24 s in between) after SDB, SDE, and NNS. They were asked to estimate three distances (i.e. 15, 25, and 35 m) before and after RS from different angles of view [i.e. in front (0°) and in side (45° left and 45° right)]. For 35 m, distance estimation was better during NNS compared to SDB and SDE for the front and the two side angles either before or after RS (p < 0.05). Concerning 25 m, distance estimation was better after compared to before RS for the front angle during the NNS session (p < 0.05). For 15 m, distance estimation was better during NNS than SDB and SDE for the front and both side angles after RS (p < 0.05). We concluded that partial sleep deprivation negatively affected the estimation of the egocentric distance for the three angles of view either at rest or after RS exercise.