Sesta e desempenho cognitivo

Orientador : Prof. Dr. Fernando Mazzilli LouzadaTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Biologia Celular e Molecular. Defesa: Curitiba, 21/03/2014Inclui referênciasÁrea de concentração : FisiologiaResumo: Os avanços científicos do último século trouxeram grandes esclarecimentos acerca das funções do sono. Entre essas funções destaca-se a associação do sono com funções cognitivas como a atenção, o aprendizado, a memória e a resolução de problemas. No entanto, pouco se sabe sobre a maneira como o sono está associado ao desempenho cognitivo. Menos ainda sobre a relação entre a sesta e o desempenho cognitivo. Nesse contexto, trabalhamos com o objetivo de avaliar o efeito de uma sesta sobre o desempenho cognitivo de jovens universitários. Para isso três experimentos foram realizados: um que avaliou o efeito da sesta sobre a consolidação de memórias não-declarativas, outro sobre a consolidação de memórias declarativas e o último que avaliou o efeito da sesta sobre a resolução de problemas. O desenho experimental foi o mesmo nos três experimentos. Os sujeitos eram treinados e após o treino tinham a oportunidade (grupo Sesta) ou não (grupo Controle) de dormir durante 90 minutos. Os sujeitos que dormiram a sesta apresentaram melhor desempenho na tarefa de memória não-declarativa e além disso, aqueles que completaram um ciclo de sono apresentaram melhor desempenho na tarefa.Com relação à memoria declarativa, apenas sujeitos que alcançaram estágio REM de sono apresentaram algum benefício da sesta sobre a consolidação desse tipo de memória. Por fim, a sesta também aumenta a chance de resolver problemas, sendo, aparentemente, o sono de ondas lentas diretamente associado a esse efeito. Essas evidências, em conjunto com outras apresentadas na literatura posicionam o sono como agente protagonista nos processos de consolidação da memória. Em conclusão, esse trabalho de tese adiciona mais uma evidência em favor de um sistema ativo de consolidação de memórias durante o sono, sugerindo que o sono é uma estratégia eficiente no enfrentamento dos desafios do dia-a-dia. Palavras-chave: Sesta, cognição, sono, memória, sono e memória, consolidação da memória, resolução de problemas.Abstract: Many discoveries have been made regarding sleep’s function in the last century. Associations between sleep and energy balance, immune system and cognition have been made. Sleep has been associated as important for different cognitive aspects such as attention, learning and memory, and problem solving. However there are still many gaps regarding the physiological process related to sleep’s function on cognition, especially on memory and problem-solving. Despite the habit of take a nap after lunch, the siesta, being common in many countries, little is known about the effect siesta cognition. Our aim is sought for the effect of a post-lunch nap on cognition. To do so, three experiments were performed, one evaluating the effect of a post-lunch nap on non-declarative memory, other evaluating the effect of a post-lunch nap on declarative memory and another one evaluating the effect of a post-lunch nap on problem-solving. The experimental design was the same for the three experiments. In short, subjects were trained and had the opportunity to sleep for 90 minutes (Siesta Group) while another set of subjects remained in quiet wakefulness for the same time (Control Group). Subjects from Siesta group showed better performance for non-declarative memory after sleep, especially if they had achieved deep sleep. The association of siesta and declarative memory was not clear, however. Only subjects who slept REM sleep showed significant effect of the siesta on one aspect of declarative memory evaluated. Regarding the problem-solving, subjects who took a nap were almost twice as likely to solve the problem as the ones who remained awake. Interesting to note that slow wave sleep seems to play important role in the problem-solving. These results add more pieces of evidences in favor of an active system of consolidation, and more, it attributes to sleep a function of optimize the cognitive function in order to overcome the everyday challenges. Key-words: Sleep, siesta, nap, memory, memory-consolidation, problem-solving

Avaliaçao do ciclo sono/vigília, da sonolencia diurna e do desempenho psicomotor de adolescentes submetidos a um programa de educaçao sobre o sono

Orientador: Fernando Mazzilli LouzadaDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Biológicas, Programa de Pós-Graduaçao em Biologia Celular e Molecular. Defesa: Curitiba, 2008Inclui bibliografia e anexosAdolescent sleep delay has been well-documented and is related to greater social pressures as well as to ontogenetic trends. As a consequence, a partial sleep deprivation is observed and morning school routine can promote excessive daytime sleepiness during schooldays and a poorly academic performance. Some studies have pointed out the positive effect of sleep educational programs. This study aimed to evaluate the effect of an Educational Sleep Program (ESP) on adolescent sleep/wake cycle, subjective sleepiness and psychomotor vigilance performance. 21 adolescents (13-14y) of a public school in Curitiba – Brazil participated in the study. Two groups were formed: Experimental (n=10), submitted to the EPS, and Control (n=11), not submitted to the EPS. Sleep/wake cycle data, onset, offset, sleep duration and sleep efficiency were recorded with actimeters; subjective sleepiness were obtained by means Karolinska Sleepiness Scale and psychomotor performance were performed by means Psychomotor Vigilance Task (PVT), before and after the ESP. The ESP consisted in activities related to the importance of sleep and sleep hygiene. It lasted four hours. Data of sleep patterns, psychomotor performance subjective sleepiness were compared by means two-way ANOVA for dependent samples - treatment (before or after intervention) and group (Control and Experimental) were considered factors. Results did not show any EPS effect on adolescents sleep/wake pattern, subjective sleepiness and psychomotor performance. Further studies with longer ESPs should be carried out to evaluate the validity of such programs as a countermeasure to prevent excessive daytime sleepiness among adolescents

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

AbstractHere our goal was to determine the magnitude of sleep-related motor skill enhancement. Performance on the finger tapping task (FTT) was evaluated after a 90min 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

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

AbstractHere our goal was to determine the magnitude of sleep-related motor skill enhancement. Performance on the finger tapping task (FTT) was evaluated after a 90min 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

Amerindian (but not African or European) ancestry is significantly associated with diurnal preference within an admixed Brazilian population

Significant questions remain unanswered regarding the genetic versus environmental contributions to racial/ethnic differences in sleep and circadian rhythms. We addressed this question by investigating the association between diurnal preference, using the morningness–eveningness questionnaire (MEQ), and genetic ancestry within the Baependi Heart Study cohort, a highly admixed Brazilian population based in a rural town. Analysis was performed using measures of ancestry, using the Admixture program, and MEQ from 1,453 individuals. We found an association between the degree of Amerindian (but not European of African) ancestry and morningness, equating to 0.16 units for each additional percent of Amerindian ancestry, after adjustment for age, sex, education, and residential zone. To our knowledge, this is the first published report identifying an association between genetic ancestry and MEQ, and above all, the first one based on ancestral contributions within individuals living in the same community. This previously unknown ancestral dimension of diurnal preference suggests a stratification between racial/ethnic groups in an as yet unknown number of genetic polymorphisms

Comparison between an African town and a neighbouring village shows delayed, but not decreased, sleep during the early stages of urbanisation

The well-established negative health outcomes of sleep deprivation, and the suggestion that availability of electricity may enable later bed times without compensating sleep extension in the morning, have stimulated interest in studying communities whose sleep pattern may resemble a pre-industrial state. Here, we describe sleep and activity in two neighbouring communities, one urban (Milange) and one rural (Tengua), in a region of Mozambique where urbanisation is an ongoing process. The two communities differ in the amount and timing of daily activity and of light exposure, with later bedtimes (≈1 h) associated with more evening and less daytime light exposure seen in the town of Milange. In contrast to previous reports comparing communities with and without electricity, sleep duration did not differ between Milange (7.28 h) and Tengua (7.23 h). Notably, calculated sleep quality was significantly poorer in rural Tengua than in Milange, and poor sleep quality was associated with a number of attributes more characteristic of rural areas, including more intense physical labour and less comfortable sleeping arrangements. Thus, whilst our data support the hypothesis that access to electricity delays sleep timing, the higher sleep quality in the urban population also suggests that some aspects of industrialisation are beneficial to sleep

Compared Heritability of Chronotype Instruments in a Single Population Sample

It is well established that the oldest chronotype questionnaire, the morningness-eveningness questionnaire (MEQ), has significant heritability, and several associations have been reported between MEQ score and polymorphisms in candidate clock genes, a number of them reproducibly across populations. By contrast, there are no reports of heritability and genetic associations for the Munich chronotype questionnaire (MCTQ). Recent genome-wide association studies (GWAS) from large cohorts have reported multiple associations with chronotype as assessed by a single self-evaluation question. We have taken advantage of the availability of data from all these instruments from a single sample of 597 participants from the Brazilian Baependi Heart Study. The family-based design of the cohort allowed us to calculate the heritability (h2) for these measures. Heritability values for the best-fitted models were 0.37 for MEQ, 0.32 for MCTQ, and 0.28 for single-question chronotype (MEQ Question 19). We also calculated the heritability for the two major factors recently derived from MEQ, “Dissipation of sleep pressure” (0.32) and “Build-up of sleep pressure” (0.28). This first heritability comparison of the major chronotype instruments in current use provides the first quantification of the genetic component of MCTQ score, supporting its future use in genetic analysis. Our findings also suggest that the single chronotype question that has been used for large GWAS analyses captures a larger proportion of the dimensions of chronotype than previously thought

Poor sleep quality and lipid profile in a rural cohort (The Baependi Heart Study)

Aim: To test the association between cardiometabolic risk factors and subjective sleep quality assessed by the Pittsburgh sleep quality index (PSQI), independent of obstructive sleep apnea (OSA) and sleep duration. Methods: A total of 573 participants from the Baependi Heart Study, a rural cohort from Brazil, completed sleep questionnaires and underwent polygraphy for OSA evaluation. Multivariable linear regression analysis tested the association between cardiovascular risk factors (outcome variables) and sleep quality measured by PSQI, adjusting for OSA and other potential confounders (age, sex, race, salary/wage, education, marital status, alcohol intake, obesity, smoking, hypertension, and sleep duration). Results: The sample mean age was 43 ± 16 years, 66% were female, and mean body mass index (BMI) was 26 ± 5 kg/m 2 . Only 20% were classified as obese (BMI ≥30). Overall, 50% of participants reported poor sleep quality as defined by a PSQI score ≥5. A high PSQI score was significantly associated with higher very-low-density lipoprotein (VLDL) cholesterol levels (beta = 0.392, p = 0.012) and higher triglyceride levels (beta = 0.017, p = 0.006), even after adjustments, including the apnea–hypopnea index. Further adjustments accounting for marital status, alcohol intake, and medication use did not change these findings. No significant association was observed between PSQI scores and glucose or blood pressure. According to PSQI components, sleep disturbances (beta = 1.976, p = 0.027), sleep medication use (beta = 1.121, p = 0.019), and daytime dysfunction (beta = 1.290, p = 0.024) were significantly associated with higher VLDL serum levels. Only the daytime dysfunction domain of the PSQI components was significantly associated with higher triglyceride levels (beta = 0.066, p = 0.004). Conclusion: Poorer lipid profile was independently associated with poor sleep quality, assessed by the PSQI questionnaire, regardless of a normal sleep duration and accounting for OSA and socio-economic status

Association between light exposure and metabolic syndrome in a rural Brazilian town

Context: Metabolic syndrome (MetS) is a complex condition comprising a ‘clustering’ of components representing cardiometabolic risk factors for heart disease and diabetes; its prevalence rate is high and consequences serious. Evidence suggests that light exposure patterns and misalignment of circadian rhythms might contribute to MetS etiology by impacting energy metabolism and glucose regulation. Objective: We hypothesised that individuals with MetS would show disrupted circadian and sleep parameters alongside differences in light exposure profiles. We investigated this using data from a cohort study in Brazil. Methods: Data from 103 individuals from the Baependi Heart Cohort Study aged between 50 and 70 were analysed. Motor activity and light exposure were measured using wrist-worn actigraphy devices. Cardiometabolic data were used to calculate the number of MetS components present in each participant, and participants grouped as MetS/non-MetS according to standard guidelines. Between-group comparisons were made for the actigraphy measures; additionally, correlation analyses were conducted. Results: Motor activity and circadian profiles showed no differences between groups. However, the MetS group presented lower light exposure during the day and higher light exposure at night. Correlation analyses, including all participants, showed that greater daytime light exposure and greater light exposure difference between day and night were associated with reduced MetS risk (a lower number of MetS components). Also, the light exposure difference between day and night correlated with body mass index across all participants. Conclusions: The observed results suggest a direct association between light exposure and MetS which appears to not be attributable to disruptions in circadian activity rhythm nor to sleep parameters. This link between light exposure patterns and MetS risk could inform possible prevention strategies

Early chronotype with advanced activity rhythms and dim light melatonin onset in a rural population

Studying communities at different stages of urbanisation and industrialisation can teach us how timing and intensity of light affect the circadian clock under real-life conditions. We have previously described a strong tendency towards morningness in the Baependi Heart Study, located in a small rural town in Brazil. Here, we tested the hypothesis that this morningness tendency is associated with early circadian phase based on objective measurements (as determined by dim light melatonin onset, DLMO, and activity) and light exposure. We also analysed how well the previously collected chronotype questionnaire data were able to predict these DLMO values. The average DLMO observed in 73 participants (40 female) was 20:03 ± 01:21, SD, with an earlier average onset in men (19:38 ± 01:16) than in women (20:24 ± 01:21; P ≤.01). However, men presented larger phase angle between DLMO and sleep onset time as measured by actigraphy (4.11 hours vs 3.16 hours; P ≤.01). Correlational analysis indicated associations between light exposure, activity rhythms and DLMO, such that early DLMO was observed in participants with higher exposure to light, higher activity and earlier light exposure. The strongest significant predictor of DLMO was morningness-eveningness questionnaire (MEQ) (beta=−0.35, P ≤.05), followed by age (beta = −0.47, P ≤.01). Sex, light exposure and variables derived from the Munich chronotype questionnaire were not significant predictors. Our observations demonstrate that both early sleep patterns and earlier circadian phase have been retained in this small rural town in spite of availability of electrification, in contrast to metropolitan postindustrial areas