Bimodal diurnal preference in undergraduate students is associated with negative health and sleep outcomes.

The bimodal preference is a fourth diurnal preference proposed by re-scoring the Morningness-Eveningness Questionnaire. The present work aimed to describe the prevalence of the bimodal preference in a sample of undergraduate students and to characterize the bimodal type in terms of their health and sleep-related outcomes. A web-based cross-sectional study conducted between September 2018 and March 2021 (convenience sampling method). The sample was composed of undergraduate students who completed an electronic form that included the Morningness and Eveningness Questionnaire, the Pittsburgh Sleep Quality Index, the Self-Compassion Scale, the Epworth Sleepiness Scale, the Hospital Anxiety and Depression Scale, and the World Health Organization Subjective Well-Being Index. The final sample consisted of 615 students (82% female, mean age: 23.4 ± 6.5 years), of whom 108 (18%) had positive bimodality indexes. Bimodal subjects comprised 48 students, 8% of the total sample. Bimodal subjects had poorer subjective sleep quality, more daytime sleepiness, lower subjective well-being, greater anxiety and depression symptoms, and lower self-compassion than morning and/or intermediate types; they did not differ from evening types. The description of bimodal diurnal preference in this population may be of interest for the design of academic policies more in line with the circadian reality of students.

Evening chronotype predicts dropout of physical exercise: a prospective analysis.

Purpose: Eveningness preference to sleep/wake and perform physical/cognitive activities has been associated with worse health outcomes, when compared to morningness preference. Physical activity is one potential mediator that could explain this relationship; however, most of these evidences come from cross-sectional design studies. Our goal was to assess whether chronotype could predict the risk of dropout of physical exercise programs. Methods: We followed 153 newly enrolled volunteers at three different gyms, from both sexes, aged between 18 and 65 years, during 12 weeks. The daily frequency of exercises in the programs was objectively measured (gym's electronic turnstiles). Using questionnaires, we collected data of variables related to demographic characteristics, health, physical activity, sleep, anthropometric and chronobiological parameters (Morningness-Eveningness Questionnaire-MEQ). Two multivariate models were created using Cox regression analysis to test the risk of dropout of physical exercise practice. Both models accounted for age, educational level, civil status, membership plan duration, physical exercise practice frequency during week 1 and chronotype (MEQ score and chronotypes). Results: Model 1 results showed that higher MEQ score was associated with a lower chance of quitting the program (HR = 0.98; CI95% 0.95-1.00; p = 0.046). Considering the chronotypes, E-types showed the highest dropout risk compared to that of M-types (HR = 2.22; CI95% 1.09-4.52; p = 0.027). Conclusion: Our results suggest that chronotype is another variable to be considered in future studies on promoting PAs in formal environments. Likewise, the practice frequency during week 1 and duration of membership plan also deserve more attention in additional studies.

Worse sleep quality predicts early drop out from physical exercise programs.

Introduction and Objective: Sleep quality (SQ) benefits from regular physical exercise (PE) practice, but the effect of SQ over behavioral aspects of PE is not well known. In this study, we tested whether sleep variables can predict the drop out risk for PE programs during a six-week critical period for habit formation at gyms. Material and Methods: We assessed 153 volunteers, freshly enrolled at three different gyms and from both sexes, with average age of 33.6 (±11.9) years. Questionnaires provided sociodemographic, health, sleep, physical activity and circadian rhythmicity information. Daily PE practice frequency was monitored using the gym's turnstiles electronic records. We created a multivariate model using Cox regression in order to test the risk of PE program drop out during the first six weeks. Results: Worse SQ predicted a higher drop out risk (HR=1.11; 95%CI = 1.02-1.21; p<0.05), even when adjusted for other potential confounding variables. Conclusion: We found that worse SQ predicted a higher early drop out from PE programs in the formal context of gyms during the first six weeks, along with other variables related to PE practice.

Child sleep habits and maternal perception during the child's first year of life / Hábitos do sono infantil e percepção materna ao longo do primeiro ano de vida da criança

Introdução: na Introdução: Na saúde infantil, o sono desempenha um papel significativo, especialmente na maturação física e cognitiva e nas capacidades de lidar com estresse, regular emoções e socializar.Objetivo: analisar hábitos do sono infantil ao longo do primeiro ano de vida e fatores associados aos despertares noturnos segundo percepções maternas.Método: estudo longitudinal, prospectivo, com acompanhamento de 144 mães e crianças no primeiro mês, terceiro/quarto mês e 12º/13º mês de idade, de um município de médio porte do interior paulista, Brasil. Hábitos de sono foram analisados com medidas de tendência central e dispersão e testes de associação válido Qui-quadrado e Exato de Fisher, nível de significância α=0,05.Resultados: o local predominante onde as crianças dormem é o mesmo quarto e mesma cama dos cuidadores parentais. A maior parte das crianças dorme em decúbito lateral e dorsal. Tempo médio de sono foi 12,5h no primeiro mês, 11,5h no terceiro/quarto mês e 11,5h no 12º/13º mês. Tempo médio do sono noturno aumentou e sono diurno diminuiu. Do primeiro mês para o 12° mês de vida, não houve mudanças nos despertares noturnos. Percepção do sono como problema aumentou de 4% para 9% entre as participantes.Conclusão: três momentos no primeiro ano de vida trazem características dos hábitos do sono infantil, sobre local onde as crianças dormem, posição de dormir, tempo médio de sono e despertares noturnos, sugerindo a importância de informações obtidas longitudinalmente. Despertares noturnos mostraram-se associados à ocorrência do desmame e à percepção materna de considerar o sono da criança um problema.

Introduction: in children's health, sleep plays a significant role, especially in physical and cognitive maturation and in the abilities to deal with stress, regulate emotions and socialize.Objective: to analyze children's sleep habits during the first year of life and factors associated with nighttime awakenings according to maternal perceptions.Methods: a longitudinal, prospective study, with follow-up of 144 mothers and their children in the first month, third/fourth month and 12th/13th month of age, in a medium-sized city in the interior of São Paulo, Brazil. Sleep habits were analyzed using measures of central tendency and dispersion and valid association tests Chi-square and Fisher's exact, significance level α=0.05.Results: the predominant place where children sleep is the same room and bed as the parental caregivers. Most children sleep in the lateral and dorsal decubitus position. Mean sleep time was 12:30h in the first month, 11:30h in the third/fourth month and 11:24h in the 12th month. Mean nighttime sleep time increased and daytime sleep decreased. From the first month to the 12th month of life, there were no changes in nocturnal awakenings. Perception of sleep as a problem increased from 4% to 9% among participants.Conclusion: three moments in the first year of life show characteristics of children's sleep habits, about where children sleep, sleeping position, average sleep time and nocturnal awakenings, suggesting the importance of information obtained longitudinally. Nocturnal awakenings were associated with the occurrence of weaning and the maternal perception about child sleep as a problem.

Association of food intake with sleep disorders in children and adolescents with obesity.

Introduction: the great increase in childhood obesity rates is well documented in the scientific literature. However, the influence of diet on sleep quality in children and adolescents still needs further research in order to be better understood. The objective of this study was to evaluate the association between diet and sleep characteristics and in children and adolescents with obesity. Methods: observational analytical cross-sectional study with prospective data collection. Forty-three children and adolescents aged between 6 and 13 years diagnosed with obesity and treated at a public tertiary care institution participated in the study. The 6-day Food Intake Registry was used to evaluate the intake of energy and macronutrients. To investigate the risk of sleep disturbances and to know the routine and characteristics of sleeping habits, the Sleep Disturbance Scale for Children (SDSC) questionnaire was used. Results: and discussion: Food intake showed association with Sleep Breathing Disorders (SBD) and Sleep Wake Transition Disorders (SWTD). The sum of all SDSC factors demonstrated the presence of pathological sleep in most patients (n = 25).

Sleep regularity in athletes: Comparing sex, competitive level and sport type.

This study aims to describe the athletes' sleep regularity using the Sleep Regularity Index (SRI) and determine whether factors, such as sex, competitive level and sport type, could affect the sleep/wake rhythm. It is a descriptive, cross-sectional study consisting of 172 athletes (25 ± 7 y old; 45 women). Seventy-three competed in team sports and 99 in individual sports. Furthermore, 56 competed in the international level, 95 in the national and 21 in the regional. We recorded the SRI values for at least 5 d via continuous actigraphy. We recorded a mean SRI value of 73 ± 12. We found no significant differences between athletes' sleep parameters in relation to sleep regularity. Furthermore, SRI data showed no correlations (Spearman's ρ) with sleep parameters, bed time and wake time. Female athletes (p = 0.001) and individual sport athletes (p = 0.001) reported better sleep regularity than their counterparts. International-level athletes reported better sleep regularity than those in other competitive levels (national: p = 0.001; regional: p = 0.024). Our study showed that international level athletes, female athletes and individual sport athletes reported better sleep regularity. Additionally, SRI data showed no correlation with athletes' sleep parameters, bed and wake time.

Daytime sleepiness in elementary school students: the role of sleep quality and chronotype.

OBJECTIVE: To investigate the occurrence of daytime sleepiness and associated sleep factors in a sample of elementary school students who attended school in the afternoon schedule. METHODS: Sleep data from 363 Brazilian public school students (12.78 ± 1.36 years, 206 girls) were obtained by applying questionnaires in classrooms. All subjects attended school in the afternoon schedule, with classes starting between 1:00 and 1:20 p.m. Daytime sleepiness was assessed by the pediatric daytime sleepiness scale; sleep quality, by the mini-sleep questionnaire; and sleep patterns and chronotypes, by the Munich chronotype questionnaire. Scores equal to or greater than 15 pediatric daytime sleepiness scale points were considered as excessive daytime sleepiness. The predictive power of sleep variables on daytime sleepiness was evaluated by a multiple linear regression. RESULTS: The subjects in the sample had an average time in bed greater than nine hours both on school days and on weekends. Nevertheless, 52.1% had an average pediatric daytime sleepiness scale score equal to or greater than 15 points, indicative of excessive daytime sleepiness. As for their quality of sleep, 41.1% had a very altered sleep. We observed, by a multiple linear regression, that quality of sleep (ß = 0.417), chronotype (ß = 0.174), mid-sleep on school days (ß = 0.138), and time in bed (ß = - 0.091) were all significant in predicting daytime sleepiness. CONCLUSION: This study showed the occurrence of excessive daytime sleepiness in non-sleep deprived students who attended school in the afternoon. The worst quality of sleep and eveningness had a greater predictive power on daytime sleepiness than time in bed. Therefore, we must consider other factors in addition to sleep duration when planning interventions for daytime sleepiness.

Changes in adolescents' sleep during COVID-19 outbreak reveal the inadequacy of early morning school schedules.

Objectives: The forced closure of schools during the COVID-19 outbreak imposed on adolescents a new reality of home-schooling. This new situation has affected adolescent sleep patterns due to the absence of the pressure to wake up earlier induced by school times during pandemic. This study aimed to investigate the changes in sleep and napping habits in Brazilian adolescents during the COVID-19 outbreak. Methods: A sample of 259 high school adolescents (mean age = 15.5 years) reported sleep and napping habits by means validated questionnaires in both baseline year (March-June 2019) and during COVID-19 lockdown (July 2020). Results: The tendency to eveningness was higher and daytime sleepiness was reduced during the social isolation. Time in bed (TIB) increased by more than 2 hours and sleep onset time was delayed during the pandemic. More adolescents reported getting enough TIB during the pandemic. Moreover, sleepiness during remote classes was reduced compared to that reported during traditional classes one year before. The nap habit decreased during the pandemic compared to the baseline year. Discussion: The lack of early wake-up pressure to attend school in the morning could explain the sleep improvements perceived during the COVID-19 outbreak. Therefore, parents, educators, and policy makers need to discuss more feasible school times for adolescents in order to implement these changes as soon as returning to presential/hybrid learning.

Daytime sleepiness in elementary school students: the role of sleep quality and chronotype

ABSTRACT OBJECTIVE To investigate the occurrence of daytime sleepiness and associated sleep factors in a sample of elementary school students who attended school in the afternoon schedule. METHODS Sleep data from 363 Brazilian public school students (12.78 ± 1.36 years, 206 girls) were obtained by applying questionnaires in classrooms. All subjects attended school in the afternoon schedule, with classes starting between 1:00 and 1:20 p.m. Daytime sleepiness was assessed by the pediatric daytime sleepiness scale; sleep quality, by the mini-sleep questionnaire; and sleep patterns and chronotypes, by the Munich chronotype questionnaire. Scores equal to or greater than 15 pediatric daytime sleepiness scale points were considered as excessive daytime sleepiness. The predictive power of sleep variables on daytime sleepiness was evaluated by a multiple linear regression. RESULTS The subjects in the sample had an average time in bed greater than nine hours both on school days and on weekends. Nevertheless, 52.1% had an average pediatric daytime sleepiness scale score equal to or greater than 15 points, indicative of excessive daytime sleepiness. As for their quality of sleep, 41.1% had a very altered sleep. We observed, by a multiple linear regression, that quality of sleep (β = 0.417), chronotype (β = 0.174), mid-sleep on school days (β = 0.138), and time in bed (β = - 0.091) were all significant in predicting daytime sleepiness. CONCLUSION This study showed the occurrence of excessive daytime sleepiness in non-sleep deprived students who attended school in the afternoon. The worst quality of sleep and eveningness had a greater predictive power on daytime sleepiness than time in bed. Therefore, we must consider other factors in addition to sleep duration when planning interventions for daytime sleepiness.

Chronic sleep restriction triggers inadequate napping habits in adolescents: a population-based study.

BACKGROUND: The prevalence of chronic sleep restriction during adolescence is a major public health issue. Napping has been adopted to alleviate sleep pressure complaints. However, it also has the potential to amplify sleep restriction due to a vicious cycle triggered by delayed sleep times. The aim of this study was to investigate sleep and napping habits in a sample of Brazilian adolescents. METHODS: This study enrolled 1554 high school students and included the evaluation of sleep times, daytime sleepiness, sleep quality, and circadian preference. The students were asked about their napping routine, ie its frequency and duration per week. RESULTS: The adolescent sleep recommendation was achieved by only 27.6% of the sample. Napping habit was reported by 58.1%, with 36.2% of nappers informing naps in 1-2 times per week. Prolonged naps were reported by 44.9% of nappers. Nappers had later median bedtime (23:30) and reduced time in bed (TIB) (median = 07:00 h) compared to non-nappers. The frequency of nappers who did not achieve satisfactory TIB was higher than non-nappers. In addition, nappers reported increased daytime sleepiness and poor sleep quality. Later bedtimes and reduced TIB were associated with longer nap duration. Increased sleepiness and poor sleep quality were linked to a higher nap frequency. CONCLUSIONS: This exploratory survey demonstrated a severe sleep restriction faced by Brazilian adolescents. Napping can be an efficient strategy to counteract sleep restriction, but it needs to be adopted with caution due to the detrimental effects of frequent and prolonged naps on nocturnal sleep.

The mediating effect of conscientiousness on the academic consequences of social jetlag.

Social jetlag (SJL) causes impairment of academic achievement; on the other hand, the personality factor of conscientiousness is related to better grades. We evaluated the impact of conscientiousness on the academic consequences of social jetlag. Undergraduate students (n = 556) were evaluated throughout their first 3 years of university education. Conscientiousness, as a mediating factor in the structural equation modeling, explained 20% of the effect of SJL on academic achievement. This is the first cohort study to evaluate the mediating effect of personality on the consequences of SJL.

Postural impairments in Parkinson's disease are not associated with changes in circadian rhythms changes.

Parkinson's disease (PD) is a progressive neurodegenerative disease, with a worldwide incidence of 1% in individuals >60 years of age. Its primary characteristics include postural impairments and changes in circadian rhythms. The authors investigated the association between postural impairment and changes in circadian rhythms in 24 PD subjects diagnosed with stages 1 to 3 on the Hoehn-Yard (HY) scale and regularly used dopaminergic medication for at least 1 year (experimental group - EG) and 24 healthy elderly individuals without a history of neurological impairment as the control group (CG). Static balance tests using a force plate were performed, and activity/rest rhythm, according to the relative amplitude of L5 and M10 values, was monitored for seven consecutive days using actimetry. The results indicated differences in posturographic indicators of mediolateral displacement (ML) [EG, 4.71 ± 0.85 mm; CG, 2.79 ± 0.53 mm (p < .0001)] and anteroposterior displacement of the center of pressure (COP) [EG, 5.61 ± 2.43 mm; CG, 8.23 ± 1.72 mm (< 0.0001)], ML velocity of the COP [EG, 2.39 ± 0.83 mm/s; CG, 1.40 ± 0.18 mm/s (p < .0001)], and total distance of the COP in the tandem stance condition [EG, 227.6 ± 75 mm; CG, 53.4 ± 6.1 mm (p < .0001)] between the EG and CG. There was no correlation between relative amplitude and posturographic data for the EG. Postural impairments were verified in comparing the EG and CG; however, there was no association between posturographic indicators and activity/rest rhythm.

Circadian ontogeny through the lens of nonparametric variables of actigraphy.

Studies focusing on human rhythmicity show that human circadian rhythm suffers constant changes across lifespan. Changes in rest-activity patterns can be studied through nonparametric variables of actigraphy: L5 (an individual's least active 5 h), M10 (an individual's most active 10 h) and RA (relative amplitude of the rest-activity rhythm). The variable RA is the normalized difference between L5 and M10 - the higher the RA, the greater the difference between these two variables. This study used the data bank of the Human Chronobiology Laboratory of Federal University of Paraná (Brazil). It analyzed actimetric data of 93 children between 4 and 11 years of age in their naturalistic context in order to describe the development of nonparametric variables. Correlation between age and L5 was significantly negative (rho = - 0.29, p = 0.004), while correlation between age and RA was significantly positive (rho = 0.31, p = 0.003). The variables M10, sL5 (start of L5) and sM10 (start of M10) did not show significant correlation to age. Furthermore, there were no statistical differences between genders. The population of this study, healthy children, has been poorly assessed by similar literature. Through our results, we have demonstrated that, as children age, L5 significantly decreases, which reflects a smaller fragmentation of circadian rhythm. As an expected consequence, RA significantly increases. In other words, these nonparametric variables of actimetry successfully demonstrate that children tend to reduce nocturnal activity as they age, a phenomenon that reflects the ongoing consolidation of circadian rhythm.

Executive functioning is preserved in healthy young adults under acute sleep restriction.

OBJECTIVES: This study aimed to evaluate if a partial morning or evening sleep restriction protocol could affect executive functioning in healthy young adults. METHODS: Participants were assigned to one of three groups: control (n=18), in which participants maintained their habitual sleep/wake cycle; morning restriction (n=17), in which volunteers terminated sleep approximately three hours earlier than the usual on the experimental night, and evening restriction (n=13), in which volunteers initiated sleep approximately three hours later than the usual on the experimental night. On the day of the experiment, they performed the Stroop Test, the Go-NoGo Test and the Iowa Gambling Task (IGT). RESULTS: When compared to the control group, neither morning nor evening sleep-restricted individuals displayed any significant deficits in: a) selective attention as assessed by the interference index (H=3.38; p=0.18) and time to performed the interference card (H=2.61; p=0.27) on the Stroop test; b) motor response inhibition as assessed by number of false alarms (H=0.8; p=0.67) on the Go-NoGo Test; and c) in decision-making as assessed by total won (H=2.64; p=0.26) and number of selected advantageous cards (H=4.43; p=0.11) on the IGT. CONCLUSION: These findings suggest that the ability to pay attention, inhibit a motor response and make decisions is preserved following approximately 3 hours of sleep restriction, regardless of its timing (in the morning or in the evening).

Impairment of sleep quality and quality of life in bimodal chronotype individuals.

There is still insufficient data about the characteristics and clinical significance of the bimodal chronotype. We evaluated more than 1000 students with Morningness-Eveningness Questionnaire, Munich Chronotype Questionnaire (MCTQ), Pittsburgh Sleep Quality Index and 36-item Short Form Health Survey. Twelve percent of the sample was bimodal and they showed similar results to intermediate chronotype in MCTQ-chronotype and social jetlag, both different from morning and evening chronotypes. However, their quality of life and sleep quality were similar to evening types, both different from morning and intermediate types. We discuss if being bimodal would be a maladaptive aspect of circadian preference.

Circadian rest-activity rhythm in chronic obstructive pulmonary disease.

To characterize circadian rest-activity rhythm in COPD, 26 cases (66.9 ± 8.5y) and 15 controls (63.0 ± 10.7y) were assessed by actimetry. Rhythm fragmentation was measured by intradaily variability (IV), while synchronization to the 24-h light-dark cycle was measured by interdaily stability (IS). The average activity during the least active 5-h period (L5) and the average activity during the most active 10-h period (M10) were used to calculate the relative amplitude mean [RAm = (M10-L5)/(M10+L5)]. COPD patients presented higher IVm (0.242 ± 0.097 vs 0.182 ± 0.063) and L5 (36.849 ± 18.239 vs 19.888 ± 12.268) and lower RAm (0.696 ± 0.134 vs 0.833 ± 0.093) than controls. Future studies on the effects of chronotherapy measures in COPD are warranted.

Tactile stimulation during sleep alters slow oscillation and spindle densities but not motor skill.

Studies using targeted memory reactivation have shown that presentation of auditory or olfactory contextual cues during sleep can bias hippocampal reactivations towards the preferential replay of the cue-associated material, thereby resulting in enhanced consolidation of that information. If the same cortical ensembles are indeed used for encoding and storage of a given piece of information, forcing the sleeping brain to re-engage in task-intrinsic information processing should disturb the natural ongoing consolidation processes and therefore impair possible sleep benefits. Here we aimed at recreating an integral part of the sensory experience of a motor skill in a daytime nap, by means of a tactile stimulation. We hypothesized that tampering with the tactile component of a motor skill during sleep would result in hindered performance at retest, due to interference between the highly congruent incoming stimuli and the core skill trace. Contrary to our predictions, the tactile stimulation did not influence neither speed nor accuracy, when compared to natural sleep. However, an exploratory sleep EEG analysis revealed stimulation-induced alterations in the abundance and cortical topography of slow oscillations and spindles. These findings suggest that despite the lack of a significant effect on motor behavior, tactile stimulation induced changes in EEG features suggestive of a possible uncoupling between the sleep oscillations thought to underlie consolidation processes, i.e. slow oscillations and sleep spindles.

Re-examining sleep׳s effect on motor skills: How to access performance on the finger tapping task?

Here our goal was to determine the magnitude of sleep-related motor skill enhancement. Performance on the finger tapping task (FTT) was evaluated after a 90 min daytime nap (n=15) or after quiet wakefulness (n=15). By introducing a slight modification in the formula used to calculate the offline gains we were able to refine the estimated magnitude of sleep׳s effect on motor skills. The raw value of improvement after a nap decreased after this correction (from ~15% to ~5%), but remained significantly higher than the control. These results suggest that sleep does indeed play a role in motor skill consolidation.

Sono e adolescência: quantas horas os adolescentes precisam dormir? / Sleep and adolescence: how many hours sleep teenagers need?

Objetivo Determinar a especificidade e a sensibilidade de uma medida para apontar o melhor ponto de corte para a duração de sono como preditor da sonolência diurna excessiva em adolescentes. Métodos Participaram do estudo 1.359 adolescentes, com idades de 14 a 21 anos, de duas cidades do sul do Brasil, que responderam a questionário de hábitos de sono e sonolência diurna. Utilizou-se a Receiver Operating Characteristic para estimar a capacidade preditiva da duração de sono para a sonolência diurna excessiva. Resultados A média de duração do sono para os adolescentes com sonolência diurna excessiva foi de 7,9 horas e para aqueles sem sonolência diurna excessiva foi de 8,33 horas (p < 0,001). A prevalência de sonolência diurna excessiva foi de 35,7%. Foi observada correlação significativa e negativa entre a duração do sono e as idades analisadas (p < 0,001). A análise de Receiver Operating Characteristic indicou duração mínima de 8,33 horas como proteção para a sonolência diurna excessiva. Conclusão Foi observada alta prevalência de sonolência diurna excessiva e propõe-se como possível duração de sono um mínimo de 8,33 horas nos dias com aula para que os adolescentes evitem esse desfecho. .

Objective Determine specificity and sensibility, to point the best cut off for the sleep duration as predictor of excessive daytime somnolence in adolescents. Methods One thousand three hundred fifty-nine adolescents aged 14 to 21 years of two cities from South Brazil answered a questionnaire about sleep habits and daytime somnolence. To estimate the predictive capacity of sleep duration for the excessive daytime somnolence was used the Receiver Operating Characteristic. Results The sleep duration mean for adolescents with excessive daytime somnolence was 7.9 hours and for those without excessive daytime somnolence was 8.33 hours (p < 0,001). The prevalence of excessive daytime somnolence was 35.7%. Significant and negative correlation between the sleep duration and the ages analyzed was observed (p < 0,001). The Receiver Operating Characteristic analysis indicated a minimum duration of 8.33 hours as protection for excessive daytime somnolence. Conclusion High prevalence of excessive daytime somnolence was observed and is proposed as a possible sleep duration a minimum of 8.33 hours of sleep in the days with classes for adolescents to avoid this outcome. .

A fresh look at the use of nonparametric analysis in actimetry.

Actimetry has been used to estimate the sleep-wake cycle instead of the rest-activity rhythm. Although algorithms for assessing sleep from actimetry data exist, it is useful to analyze the rest-activity rhythm using nonparametric methods. This would then allow rest-activity rhythm stability, fragmentation and amplitude to be quantified. In addition, sleep and wakefulness efficiency can be quantified separately. These variables have been used in studies analyzing the effect of age, diseases and their respective treatments on human circadian rhythmicity. In this study, we carried out a comprehensive analysis of the main results from published articles and devised a functional model of interaction among the several components involved in generating the sleep-wake cycle. The nonparametric variables render it possible to infer the main characteristics of circadian rhythms, such as synchronization with a zeitgeber, and its amplitude and robustness.