Nap Duration Research Articles

Association analyses of the autosomal genome and mitochondrial DNA with accelerometry-derived sleep parameters in depressed UK biobank subjects

BackgroundThe bidirectional relationship between sleep disturbances and depression is well documented, yet the biology of sleep is not fully understood. Mitochondria have become of interest not only because of the connection between sleep and metabolism but also because of mitochondria's involvement in the production of reactive oxygen species, which are largely scavenged during sleep. MethodsGenome-wide association studies (GWAS) of eight accelerometry-derived sleep measures were performed across both the autosomal and mitochondrial DNA (mtDNA) among two severity levels of depression in UK Biobank participants. We calculated SNP heritability for each of the sleep measures. Linear regression was performed to test associations and mitochondrial haplogroups. ResultsVariants included in the GWAS accounted for moderate heritability of bedtime (19.6%, p = 4.75 × 10−7), sleep duration (16.6%, p = 8.58 × 10−6) and duration of longest sleep bout (22.6%, p = 4.64 × 10−4). No variants passed genome-wide significance in the autosomal genome. The top hit in the severe depression sample was rs145019802, near GOLGA8B, for sleep efficiency (p = 1.17 × 10−7), and the top hit in the broad depression sample was rs7100859, an intergenic SNP, and nap duration (p = 1.25 × 10−7). Top mtDNA loci were m.12633C > A of MT-ND5 with bedtime (p = 0.002) in the severe sample and m.16186C > T of the control region with nap duration (p = 0.002) in the broad sample. ConclusionSNP heritability estimates support the involvement of common SNPs in specific sleep measures among depressed individuals. This is the first study to analyze mtDNA variance in sleep measures in depressed individuals. Our mtDNA findings, although nominally significant, provide preliminary suggestion that mitochondria are involved in sleep.

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.

Prevalence and associated factors of cognitive impairment among the elderly population: A nationwide cross-sectional study in China.

Cognitive impairments are associated with increased risk for progression to dementia. In China, limited surveys have been conducted to estimate the national prevalence and risk factors associated with cognitive impairment in China. This study aims to assess the national prevalence and modifiable risk factors for cognitive impairments in the Chinese elderly population. This cross-sectional study was based on the 2018 China Health and Retirement Longitudinal Study. The Mini Mental State Examination (MMSE) is recommended to test for cognitive impairment. Univariate and multivariate logistic regression models were used in assessing risk factors for cognitive impairments in the Chinese elderly population. A total of 3768 participants aged 60 years or older were enrolled in this study. The national prevalence of cognitive impairments was 22.24% in China, and the prevalence of cognitive impairment was higher in the south-west region than in the north region (29.94 vs. 16.53%, p < 0.05). The risk for cognitive impairments was higher in the following participants: not married or not living with spouse relative to married with spouse present (OR = 1.39, 95% CI, 1.15-1.70; p = 0.001), nap duration of ≥ 90 min relative to 30-60 min (OR = 1.54, 95% CI, 1.20-1.98; p = 0.001), sleep duration of ≥ 8 h relative to 6-8 h (OR = 1.73, 95% CI, 1.29-2.31; p < 0.001), and depression relative to no depression (OR = 1.67, 95% CI, 1.41-1.97; p < 0.001). The risk of cognitive impairment was lower in participants living in the urban areas relative to the rural areas (OR = 0.57, 95% CI, 0.47-0.69; p < 0.001) and consuming alcohol once a month relative to never consuming alcohol (OR = 0.69, 95% CI, 0.51-0.94; p = 0.02). Cognitive impairment prevalence was high in the Chinese elderly population. The potentially modifiable risk factors for cognitive impairment should be further assessed in the development of interventions for the elderly Chinese population.

P033 Associations between sleep and emotional self-regulation in toddlers

Abstract Introduction Emotional self-regulation (ESR) skills are vital for mental and physical health. There is growing evidence linking sleep to ESR in school-aged children, but associations in toddlers remain unclear. The current study examined associations between toddlers’ sleep duration and behaviors and ESR. Materials and methods This study utilized baseline data from 1358 toddlers (Mage=26±3.9mo) from the Let’s Grow trial. Total sleep duration was calculated by summing parent-reported average nighttime sleep and daytime nap duration. Sleep behaviors (bedtime routine, bedtime resistance, sleep latency, and night waking) were assessed using the Children’s Sleep Habits Questionnaire and Brief Infant Questionnaire. Toddlers’ ESR skills were assessed via a 4-item parent-report scale adopted from the Fast Track Project Child Behaviour Questionnaire, with a lower score indicating better ESR. Linear regression models assessed associations of sleep duration and behaviors with ESR. Results Toddlers’ average daily total sleep, nighttime sleep, and nap duration were 12.1h, 10.6h, and 1.5h, respectively. Girls and boys had similar nighttime sleep, total sleep, and ESR scores. However, girls had longer naps than boys (1.6h vs 1.4h, t=-3.5, p=0.0004). Total sleep, nighttime sleep, and nap duration were inversely associated with ESR (all p&amp;lt;0.01), indicating that higher sleep duration was associated with better ESR. Sleep behaviors were positively associated with ESR (all p&amp;lt;0.01), with more problem sleep behaviors associated with poorer ESR. Conclusion Initial results suggest that improving sleep duration and behaviors are associated with better ESR in toddlers. Supporting parents to improve their toddlers’ sleep may help foster better ESR skills.

Effects and differences of sleep duration on the risk of new-onset chronic disease conditions in middle-aged and elderly populations

BackgroundFew longitude cohort studies investigated the risk of the duration of nighttime sleep and naps to the new-onset common chronic disease conditions (CDCs) in middle-aged (45-60) and the elderly (age ≥ 60) populations using an age-stratified strategy. MethodsThe 7025 participants from The China Health and Retirement Longitudinal Study were screened as eligible subjects. Established 13 cohorts with CDCs, acquired their’ sleep records in 2011, and obtained new-onset incidents of CDCs during follow-up in 2011-2018. Performed risk association analyses between sleep duration and 13 new-onset CDCs respectively. ResultsNew-onset risk of four CDCs decreased with increasing nighttime sleep (p-nonlinear>0.05). The risk threshold was approximately 7 hours in middle-aged people and 6 hours in the elderly.For the middle-aged population, compared with 7-9hours sleep, <5hour and 5-7hours nighttime sleep were associated with 1.312∼1.675 times more risk of hypertension, kidney disease, diabetes or high blood sugar status, and multimorbidity; Compared with no nap, a 0-30 min nap was associated with 1.413(1.087∼1.837) times the heart disease risk.In the elderly, < 5 hours of night sleep was a significant risk factor for four CDCs including kidney disease and multimorbidity, etc. A long night's sleep (>9 hours) was connected with 61.2% reduction in risk of memory disease, a >90 min nap increased 62% risk of memory disease, and a 0-30 min nap was associated with higher risks of heart disease, hypertension, and a lower kidney disease risk. ConclusionsNighttime sleep and daytime naps may have their own implications for the new-onset CDCs' risk in the aging process.

Causal relationships of excessive daytime napping with atherosclerosis and cardiovascular diseases: a Mendelian randomization study.

Previous observational studies have found conflicting evidence on the relationship between daytime napping and incident cardiovascular diseases (CVDs), but it remains unclear whether these associations present causality. This study aims to verify whether and why there is a causal relationship between these parameters, and whether there is an etiological basis. A two-sample Mendelian randomization analysis was performed using 79 single nucleotide polymorphisms associated with daytime napping. Summary-level data for coronary atherosclerosis, peripheral atherosclerosis, total CVD, and five CVD outcomes were obtained from the FinnGen study. Meta-analyses were aimed at investigating the relationships of excessive daytime napping with total CVD, coronary heart disease, myocardial infarction (MI), and stroke incidence. Subgroup, network meta-analysis (NMA) and trial sequential analysis (TSA) were also performed in this study. The inverse-variance weighted method demonstrated that a genetic predisposition to more frequent daytime napping was significantly associated with higher odds of coronary atherosclerosis (odds ratio [OR] = 1.55, 95% confidence interval [CI]: 1.11 to 2.17), MI (OR = 1.63, 95% CI: 1.06 to 2.50), and heart failure (OR = 1.80, 95%CI: 1.28 to 2.52). In NMA, an increased risk of developing CVD in people who napped for more than 60 min a day than those who did not nap was demonstrated and then supported by TSA results (summary relative risk = 1.98, 95% CI: 1.39 to 2.82). Habitual daytime napping is causally associated with an increased risk of incident CVD primarily via the development of coronary atherosclerosis. An average napping duration of more than 60 min is associated with an elevated risk of CVD in all participants.

Night shifts in interns: Effects of daytime napping on autonomic activity and cognitive function.

ObjectiveNight shifts have adverse cognitive outcomes that might be attenuated by daytime napping. The neurovisceral integration model suggests that resting vagally mediated heart rate variability (vmHRV) is linked with cognitive function. This study investigated the relationship between resting vmHRV and cognitive function after different nap durations in interns after shift work.MethodsA total of 105 interns were randomly allocated to one of three groups (non-nap, n = 35; 15-min nap, n = 35; 45-min nap, n = 35) to perform cognitive tests and resting vmHRV at 12:00, 15:00 and 18:00. Information processing (digit symbol substitution test; DSST), motor speed (finger tapping test; FTT), response selection (choice reaction time; CRT), and attention shifts (shifting attention test; SAT) were assessed. Resting vmHRV was assessed at baseline and during each cognitive task across groups.ResultsCompared with the non-nap control, the 15-min and 45-min naps improved all outcome measures (including subjective sleepiness and cognitive performance) at 15:00, with some benefits maintained at 18:00. The 15-min nap produced significantly greater benefits on the FTT at 15:00 after napping than did the 45-min nap. Resting vmHRV was significantly correlated with DSST and SAT performance. In addition, FTT performance was the only significant predictor of DSST performance across different nap durations.ConclusionOur results demonstrate links between daytime napping (in particular, a 15-min nap) and improved cognitive control in relation to autonomic activity after shift work in interns. These results indicated that autonomic activity when awake plays a crucial role in DSST and SAT performance and facilitated the understanding of differences in neurocognitive mechanisms underlying information processing after different nap durations.

Sleep and circadian rhythm profiles in seasonal depression

Sleep and circadian rhythm disruptions are symptoms of, and hypothesized underlying mechanisms in, seasonal depression. Discrepant observational findings and mixed responses to sleep/circadian-based treatments suggest heterogenous sleep and circadian disruptions in seasonal depression, despite these disruptions historically conceptualized as delayed circadian phase and hypersomnia. This study used a data-driven cluster analysis to characterize sleep/circadian profiles in seasonal depression to identify treatment targets for future interventions.Biobehavioral measures of sleep and circadian rhythms were assessed during the winter in individuals with Seasonal Affective Disorder (SAD), subsyndromal-SAD (S-SAD), or nonseasonal, never depressed controls (total sample N = 103). The following variables were used in the cluster analysis: circadian phase (from dim light melatonin onset), midsleep timing, total sleep time, sleep efficiency, regularity of midsleep timing, and nap duration (all from wrist actigraphy). Sleep and circadian variables were compared across clusters and controls.Despite limited sleep/circadian differences between diagnostic groups, there were two reliable (Jaccard Coefficients >0.75) sleep/circadian profiles in SAD/S-SAD individuals: a ‘Disrupted sleep’ cluster, characterized by irregular and fragmented sleep and an ‘Advanced’ cluster, characterized by early sleep and circadian timing and longer total sleep times (>7.5 h). Clusters did not differ by depression severity. Midsleep correlated with DLMO (r = 0.56), irregularity (r = 0.3), and total sleep time (r = −0.27).Sleep and circadian disruptions in seasonal depression are not uniformly characterized by hypersomnia and circadian phase delay. Presence of distinct sleep and circadian subgroups in seasonal depression may predict successful treatment response. Prospective assessment and tailoring of individual sleep and circadian disruptions may reduce treatment failures.

Association of elevated glycated hemoglobin and obesity with afternoon napping for more than 1 h in young and middle-aged healthy adults.

IntroductionSleep has different patterns followed worldwide and can be influenced by social, cultural, and environmental factors. Daytime napping is commonly practiced in different parts of the world with controversial results of its effect on glucose metabolism. The current study aims to examine the association of afternoon napping and night sleep duration with metabolic derangements.MethodsThis is a cross-sectional study involving young adults and middle-aged subjects. Anthropometric measurements were taken for height and weight and hip and waist ratio. Consented subjects were asked to wear actigraphy for 1 week and run their usual daily activities. Home sleep apnea testing was performed to exclude obstructive sleep apnea. Subjects had been asked to come fasting on day seven for blood collection to test for fasting glucose, glycated hemoglobin, lipid profile, and insulin.ResultsA total of 405 subjects were involved to complete the study (52% male, 48% female). The mean age of participants was 32.8 ± 11.5 years. The study indicated that the duration of afternoon napping was significantly associated with abnormal glycated hemoglobin (HbA1c > 5.7%) (p = 0.01) and body mass index (p = 0.046) independent of age, gender, and nocturnal sleep duration. Nocturnal sleep duration was associated with increased insulin level (p = 0.04).ConclusionAfternoon napping is associated with an increased level of glycated hemoglobin and obesity and that may predispose to the development of type 2 diabetes mellitus.

Short total sleep duration and poor sleep quality might be associated with asthenozoospermia risk: A case-control study.

Sleep has been related to a variety of health outcomes. However, no association between sleep and asthenozoospermia has been reported. The aim of this study is to first investigate the relationship between sleep status and asthenozoospermia risk. A case-control study, including 540 asthenozoospermia cases and 579 controls, was performed from June 2020 to December 2020 in the infertility clinic from Shengjing Hospital of China Medical University. Data on sleep status were collected by Pittsburgh sleep quality index questionnaires and asthenozoospermia was diagnosed based on the World Health Organization guidelines. Odds ratio (OR) with 95% confidence interval (95% CI) was calculated by logistic regression analysis to assess the aforementioned association. Results of this study demonstrated that compared with total sleep duration of 8–9 h/day, < 8 h/day was related to asthenozoospermia risk (OR: 1.44, 95% CI: 1.05–1.99); compared to good sleep quality, poor sleep quality was associated with asthenozoospermia risk (OR: 1.35; 95% CI: 1.04–1.77). There were multiplicative model interaction effects between sleep quality and tea drinking (p = 0.04), rotating night shift work (p < 0.01) on asthenozoospermia risk. However, we failed to detect any associations between night sleep duration, daytime napping duration, night bedtime, wake-up time, sleep pattern and asthenozoospermia risk. In conclusion, short total sleep duration and poor sleep quality might be related to asthenozoospermia risk. Further well-designed prospective studies are warranted to confirm our findings.

Effects of Melatonin Treatment on Perioperative Sleep Quality: A Systematic Review and Meta-Analysis with Trial Sequential Analysis of Randomized Controlled Trials.

PurposePerioperative sleep disorders have attracted much attention due to their high prevalence and severe harm, and the current treatment methods are insufficient. Some randomized controlled trials (RCTs) have produced controversial results on whether melatonin can improve perioperative sleep quality. This review aimed to evaluate the effects of melatonin treatment on perioperative sleep quality.Patients and MethodsA systematic search of six databases was performed to identify RCTs investigating melatonin and perioperative sleep. The outcomes analyzed were subjective sleep quality, sleep latency (SL), total sleep time (TST), sleep efficiency (SE), the behavior of awakenings and daily naps, and the incidence of poor sleep quality. RevMan 5.4 and Stata 16 software was used for the meta-analysis and sensitivity analysis, and trial sequential analysis was conducted using TSA 0.9.5.10 Beta software. This study was registered in PROSPERO (registration number: CRD42022311378).Results10 studies containing 725 participants were included. Melatonin improved postoperative subjective sleep quality (SMD: −0.30; 95% CI: [−0.47, −0.14]; P = 0.0004) but not preoperative sleep quality (MD: −2.76; 95% CI: [−10.44, 4.91]; P = 0.48). In the postoperative period, 6mg dose had the best efficacy (SMD: −0.31; 95% CI: [−0.57, −0.04]; P = 0.02). Melatonin increased postoperative TST (P = 0.02) and SE (P = 0.002) and decreased the incidence of postoperative poor sleep quality (P = 0.002) but had no effect on SL (P = 0.11), the number and duration of awakenings (P = 0.28; P=0.55), and the number and duration of daily naps (P = 0.26; P = 0.38). The trial sequential analysis showed that the accumulated Z value crossed both the traditional boundary value and the TSA boundary value, further confirming the stability of the result of the meta-analysis.ConclusionMelatonin treatment can improve postoperative sleep quality. A 6mg daily dose of melatonin may have a better beneficial effect, which needs further exploration. This study supports the application of melatonin for improving postoperative sleep quality.

Association of sleep quality and nap duration with cognitive frailty among older adults living in nursing homes.

BackgroundSleep status, including sleep quality and nap duration, may be associated with frailty and cognitive impairment in older adults. Older adults living in nursing homes may be more prone to physical and cognitive frailties. This study aimed to investigate the association between sleep quality and nap duration, and cognitive frailty among older adults living in nursing homes.MethodsThis study included 1,206 older adults aged ≥ 60 years from nursing homes in Hunan province, China. A simple frailty questionnaire (FRAIL scale) was used and Mini-Mental State Examination was conducted to assess physical frailty and cognitive impairment, respectively, to confirm cognitive frailty. The Pittsburgh Sleep Quality Index was used to assess the sleep quality. Nap duration was classified as follows: no, short (≤30 min), and long (>30 min) napping. Multinomial logistic regression was conducted to estimate the odds ratio (OR) and 95% confidence interval (CI).ResultsThe prevalence of cognitive frailty among the older adults in nursing homes was 17.5%. Approximately 60.9% of the older adults had a poor sleep quality. Among the 1,206 participants, 43.9% did not take naps, 29.1% had short naps, and 26.9% had long naps. After adjusting for all covariates, poor sleep quality (OR 2.53; 95% CI 1.78–3.59; P < 0.001) and long nap duration (OR 1.77; 95% CI 1.19–2.64; P = 0.003) were associated with higher odds of cognitive frailty, but short nap duration (OR 0.60; 95% CI 0.40–0.89; P = 0.012) was associated with low prevalence of cognitive frailty.ConclusionPoor sleep quality and long nap duration are significantly associated with high risk of cognitive frailty among the older adults in nursing homes. Short nap duration was associated with low prevalence of cognitive frailty. However, these associations require further validation in older adults.Clinical trial registrationhttps://osf.io/57hv8.

Mediating effects of sleep duration on the association between natural menopause and stroke risk among Chinese women.

BackgroundSleep disturbance is commonly reported by menopausal women. Stroke risk and poor stroke outcomes in women have usually been attributed to menopause. This study aimed to investigate the mediating effect of sleep duration on relationship between menopause and risk of stroke in natural menopause women.Materials and methodsA cross-sectional study was performed, and participants were recruited through a multistage, stratified, probability proportional to size sampling method in this research. The stroke risk was measured using the risk assessment form for high-risk stroke population. The average sleep duration was calculated by adding up night sleep and afternoon nap duration. Multivariate regression analysis was conducted to identify the association between menopause, sleep duration, and stroke risk. The direct and indirect effects of menopause on stroke risk were analyzed by using the sleep duration in a mediation framework.ResultsPerimenopause, menopause, average sleep duration, and night sleep duration were significantly associated with stroke risk (P < 0.001), after adjusting for covariates. Perimenopause and menopause were significantly related to average sleep duration (P < 0.001) and night sleep duration (P < 0.001). The average sleep duration (ab = 0.016, 95% CI: 0.003, 0.030; ab = −0.048, 95% CI: −0.070, −0.027) partially mediated the relationship between menopause and stroke risk. And night sleep duration (ab = 0.024, 95% CI: 0.009, 0.040; ab = −0.054, 95% CI: −0.077, −0.033) played a major mediating role, in which night sleep duration of ≤5 h mediated the link between both perimenopause (ab = 0.707, 95% CI: 0.392, 1.021) and menopause (ab = −0.787, 95% CI: −1.096, −0.478) and stroke risk; both night sleep duration of >8–9 h (ab = 0.079, 95% CI: 0.010, 0.193) and >9 h (ab = 0.379, 95% CI: 0.086, 0.712) had mediating effects on perimenopause and stroke risk.ConclusionA significant relationship between menopause and stroke risk factors among natural menopausal status was found in this study. The average sleep duration, especially night sleep duration, partially mediated the association between menopause and stroke risk, which is a novel insight to the progression of stroke risk in Women. Suitable prevention methods and interventions for sleep in menopausal women may reduce the risk of stroke.

Effects of 90 Min Napping on Fatigue and Associated Environmental Factors among Nurses Working Long Night Shifts: A Longitudinal Observational Study.

For nurses working long night shifts, it is imperative that they have the ability to take naps to reduce fatigue, and that an appropriate environment is prepared where such naps can be taken. We verified the effects of 90 min napping on fatigue and the associated factors among nurses working 16-h night shifts. We investigated 196-night shifts among 49 nurses for one month. Wearable devices, data logging devices, and questionnaires were used to assess nap parameters, fatigue, and environmental factors such as the napping environment, ways of spending breaks, and working environment. Nurses who nap at least 90 min on most night shifts had more nursing experience. Multivariable logistic regression analysis showed that the environmental factors significantly associated with total nap duration (TND) ≥ 90 min were noise, time spent on electronic devices such as cellphones and tablets during breaks, and nap break duration. The night shifts with TND ≥ 90 min showed lower drowsiness after nap breaks and less fatigue at the end of night shift compared to those with TND < 90 min. Nurses and nursing managers should recognize the importance of napping and make adjustments to nap for at least 90 min during long night shifts.

Sleep Pattern Is Related to Mental Health among Chinese Collegiate Student Athletes.

Regarding the association between sleep and napping duration and mental health in young and older adults, some studies indicated a positive association, while others indicated a negative, or no, association between them. Moreover, collegiate student athletes have different mental health stressors, such as training pressure, improving sports performance, and relationships with coaches. Therefore, sleep is important for athletes. Whether sleep duration is related to their mental health is unclear. Thus, this study aimed to examine the association between nighttime sleep duration, daytime napping duration, and mental health among collegiate student athletees. This cross-sectional study included 700 college athletes. Sleep and daytime napping durations were assessed using a self-reported questionnaire. The Zung Self-rating Depression Scale and Generalized Anxiety Disorder-7 assessed mental health. A multivariate logistic regression analysis was conducted to examine the adjusted association between sleep duration and mental health. In this study, the odds ratios for depression and anxiety symptoms were significantly higher for short sleep duration (<7 h). Additionally, a significant positive association was found between daytime napping duration and the prevalence of depression. This study indicates that short nighttime sleep and long daytime napping duration may be risk factors for collegiate student athletes’ mental health, having important implications for educators and coaches.

Associations of sleep characteristics with cognitive and gross motor development in toddlers

ObjectiveTo examine cross-sectional associations of sleep characteristics (duration, consolidation, timing, variability) with cognitive and gross motor development in toddlers. MethodsParticipants were 205 toddlers (19.6 ± 4.3 months) from the GET-UP! Study. Nap/nighttime sleep onset and offset were measured using an accelerometer and used to calculate nap/nighttime sleep duration. Total sleep duration was calculated and classified as meeting or not meeting the sleep recommendation of the Australian 24-Hour Movement Guidelines (11-14 h/d). Nighttime sleep ratio (ie, nighttime sleep duration: total sleep duration), indicative of consolidation, was expressed as a percent value. Nighttime sleep midpoint (ie, the midpoint between nighttime sleep onset and offset), indicating the lateness of sleep schedules, was converted to a decimal hour. For sleep variability, the intraindividual standard deviation of nighttime sleep duration and nighttime sleep midpoint was calculated, respectively. Cognitive development (Bayley Scales of Infant and Toddler Development-III) and specific domains of gross motor development (Peabody Developmental Motor Scales, 2nd edition) were measured. ResultsShorter nap duration (B = -0.87, 95%CI: -1.71, -0.02) and higher nighttime sleep ratio (B = 0.13, 95% CI: 0.02, 0.24) were associated with better cognitive development. Regarding gross motor development, positive associations were found for nighttime sleep duration (object manipulation: B = 0.26, 95% CI: 0.01, 0.51; gross motor quotient: B = 1.21, 95% CI: 0.04, 2.38) and total sleep duration (object manipulation: B = 0.28, 95% CI: 0.03, 0.52); negative associations were found for nighttime sleep midpoint (stationary: B = -0.31; 95% CI: -0.58, -0.06) and nighttime sleep duration variability (stationary: B = -0.32, 95% CI: -0.64, -0.004). ConclusionsIn toddlers, more consolidated sleep may be an indicator of better cognitive development. Promoting longer and more consistent nighttime sleep duration, as well as an earlier nighttime sleep schedule, may facilitate gross motor development. However, our findings for the associations of sleep characteristics with cognitive and gross motor development need to be confirmed in prospective studies.

Daily relations between nap occurrence, duration, and timing and nocturnal sleep patterns in college students

Objective/DesignSleep patterns change during college, and students may nap to compensate for lost sleep. Despite the increased prevalence of napping among students, few studies have investigated daily relations between napping and nocturnal sleep, as well as how timing of naps and nocturnal sleep might influence one another. The present study used daily diaries to capture the occurrence, timing, and duration of napping and relation to nocturnal sleep. Setting/ParticipantsDaily diary data, collected for 4-7 days, from 654 college students from a mid-sized midwestern university (81.5% female). MeasurementParticipants reported nightly sleep durations, bedtimes, and wake times as well as nap durations and nap start times. ResultsMultilevel modeling (MLM) and multi-level logistic regressions revealed bidirectional relations between nocturnal sleep and napping. Regarding nocturnal sleep and its relation to next day napping, nocturnal sleep (including shorter duration and later bedtime) was associated with increased odds of napping and longer napping the following day. Shorter sleep duration was also associated with taking an earlier nap, while later bedtime was associated with a later nap the following day. Regarding napping and its association with same-night nocturnal sleep, taking a nap was associated with longer sleep duration that night, however, later nap start times and longer nap durations were associated with later bedtimes that night. ConclusionsFindings provide evidence for bidirectional associations between napping and nocturnal sleep. Future studies are needed to explore how naps could be optimized to promote nocturnal sleep among college students, as well as for whom naps might be most beneficial.

Self-reported daytime napping, daytime sleepiness, and other sleep phenotypes in the development of cardiometabolic diseases: a Mendelian randomization study.

Sleep disorders are associated with an increased risk of cardiometabolic diseases in observational studies, but the causality remains unclear. In this study, we leveraged two-sample Mendelian randomization (MR) analyses to assess the causal associations of self-reported daytime napping, daytime sleepiness, and other sleep phenotypes with cardiometabolic diseases including ischaemic stroke (IS), coronary artery disease (CAD), heart failure (HF), and Type 2 diabetes mellitus (T2DM). We selected genetic variants as instrumental variables for self-reported daytime napping, daytime sleepiness, morning person, insomnia, short sleep duration, and long sleep duration from European-descent genome-wide association studies (GWASs). Summary statistics for cardiometabolic diseases originated from four different GWASs with a total of 2 500 086 participants. We used the inverse-variance weighted method to explore the role of self-reported sleep phenotypes on the aetiology of cardiometabolic diseases in the main analyses, followed by several sensitivity analyses for robustness validation. Genetically predicted self-reported daytime napping [T2DM: OR, 1.56 (95% confidence interval, 1.21-2.02)], insomnia [IS: OR, 1.07 (1.04-1.11)]; CAD: OR, 1.13 (1.08-1.17); HF: OR, 1.10 (1.07-1.14); T2DM: OR, 1.16 (1.11-1.22); and short sleep duration [CAD: OR, 1.37 (1.21-1.55)] were causally associated with an elevated risk of cardiometabolic diseases. Moreover, genetically determined self-reported daytime sleepiness [CAD: OR, 2.05 (1.18-3.57); HF: OR, 1.82 (1.15-2.87)] and morning person [HF: 1.06 OR, (1.01-1.11)] had potential detrimental effect on cardiometabolic risks. Self-reported daytime napping, insomnia, and short sleep duration had causal roles in the development of cardiometabolic diseases, while self-reported daytime sleepiness and morning person was the potential risk factor for cardiometabolic diseases.

Sleep in Paralympic athletes and its relationship with injuries and illnesses

ObjectivesTo evaluate sleep characteristics and investigate the relationship of sleep with injuries and illnesses in Paralympic athletes. DesignCross-sectional. SettingSports Training Center. Participants20 Paralympic athletes of athletics, swimming, and powerlifting. OutcomesInjury and illnesses were recorded during the sports season through the Oslo Sports Trauma Research Center questionnaire (OSTRC-BR). Sleep-wake pattern was monitored for 2 weeks using actigraphy. Chronotype, sleep quality, sleep behavior, and sleep complaints were cross-sectionally collected. ResultsPoor sleep quality and poor sleep behavior were highly prevalent. The mean total sleep time was 6.57 ± 49.91. Duration of naps (r= −0.46; p=0.04) was associated with occurrence of health problems; frequency of insomnia (r= 0.51; p= 0.02), Pittsburgh Sleep Quality Index score (r= 0.45; p=0.04), and frequency of awakenings at night (r= 0.58; p= 0.01) were associated with severity of health problems; frequency of movements during sleep was associated with OSTRC-BR cumulative score (r= 0.58; p=0.00); and frequency of nightmares was associated with OSTRC mean score. ConclusionsParalympic athletes tend to report poor sleep quality, have poor sleep behavior and sleep less than the recommended. Insomnia symptoms, awakenings at night, movements during sleep and poor sleep quality were associated with the occurrence and/or severity of health problems.

Association Between Nap Duration and Cognitive Functions Among Saudi Older Adults.

PurposeCurrent evidence of whether napping promotes or declines cognitive functions among older adults is contradictory. The aim of this study was to determine the association between nap duration and cognitive functions among Saudi older adults.MethodsOld adults (> 60 years) were identified from the Covid-19 vaccine center at Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia between May and August 2021. Face-to-face interviews were conducted by a geriatrician or family physicians. Data collected for each participant included sociodemographic, sleep patterns, health status and cognitive functions. St. Louis University mental status (SLUMS) was used to assess the cognitive functions. A multi-Linear regression model was used to determine the association between cognitive functions and nap duration.ResultsTwo-hundred participants (58 females) aged 66 ± 5 years were recruited. Participants were categorized according to their nap duration into non-nappers (0 min), short nappers (> 0- ≤ 30 min), moderate nappers (> 30–≤ 90 min), and extended nappers (> 90 min). The mean duration of the nap was 49.1 ± 58.4 min. The mean SLUMS score was 24.1 ± 4.7 units. Using the multi-linear regression model, the mean total SLUMS score for extended nappers was, on average, significantly lower than non-nappers [−2.16 units; 95% CI (−3.66, −0.66), p = < 0.01] after controlling for the covariates (age, sex, education level, sleep hours, diabetes mellitus, hypertension, pain).ConclusionsExtended napping was associated with deterioration in cognitive function among Saudi older adults.