Subjective sleep need and daytime sleepiness in adolescents / Necessidade subjetiva de sono e sonolência diurna em adolescentes

ABSTRACT Objective: To analyze the contribution of subjective sleep need for daytime sleepiness in adolescents, and to compare questions about sleep, age and body mass index between adolescents who considered to sleep enough and those who reported the need for more sleep. Methods: This is a descriptive, epidemiological and cross-sectional study. Data collection was performed in August 2016, with 773 adolescents aged 14-19 years old, from Paranaguá, Paraná, Southern Brazil. The analysis included the following variables: time in bed, half-sleep phase, sleep need, social jetlag, daytime sleepiness, body mass index and physical activity. Results: The prevalence of adolescents with subjective need for sleep was 73.0%, with an average need of 1.7 extra hours of sleep. These adolescents woke up earlier (p<0.001) and slept less on school days (p<0.001). The need for more sleep was associated with higher daytime sleepiness scores (rho=0.480; p<0.001) and with later half-sleep phase (rho=0.200; p<0.001). No correlation was identified between the sleep need and time in bed (rho=-0.044; p=0.225). The subjective sleep need was the variable with the greatest explanatory power for daytime sleepiness (24.8%; p<0.001). In addition, the less adolescents practiced physical activity, the higher their daytime sleepiness scores (rho=-0.117; p<0.001). Conclusions: The subjective sleep need has an important role in explaining daytime sleepiness among adolescents. Adolescents who needed to sleep more reported waking up early and experienced sleep deprivation during class days; they also woke up later on the weekends and experienced more daytime sleepiness, compared to those who believed they had enough sleep.

RESUMO Objetivo: Analisar a contribuição da necessidade subjetiva de sono para a sonolência diurna em adolescentes e comparar questões sobre sono, idade e índice de massa corporal entre os adolescentes que consideram dormir o suficiente e os que julgam necessitar dormir mais. Métodos: Estudo descritivo, epidemiológico e transversal, cuja coleta de dados ocorreu em agosto de 2016 em 773 adolescentes de 14 a 19 anos de Paranaguá, PR, Brasil. As variáveis de análise foram tempo de cama, meia fase do sono e necessidade de mais horas de sono, além do jetlag social, sonolência diurna, índice de massa corpórea (IMC) e atividade física. Resultados: A prevalência de adolescentes com necessidade subjetiva de sono foi 73,0%, sugerindo precisar, em média, de 1,7 hora a mais de sono. Estes acordavam mais cedo (p<0,001) e dormiam menos nos dias de aula (p<0,001). A necessidade de dormir mais associou-se a maiores pontuações de sonolência diurna (rho=0,480; p<0,001) e com meia fase do sono mais tardia (rho=0,200; p<0,001). Não foi identificada correlação entre necessidade de sono e tempo de cama (rho=-0,044; p=0,225). A necessidade subjetiva de sono foi a variável com maior poder explicativo da sonolência diurna (24,8%; p<0,001). Além disso, quanto menos os adolescentes praticavam atividade física, maiores as pontuações de sonolência diurna (rho=-0,117; p<0,001). Conclusões: A percepção subjetiva de sono teve papel importante para explicar a sonolência diurna dos adolescentes. Os jovens que precisavam dormir mais relataram acordar mais cedo e apresentavam privação de sono durante os dias de aula, acordaram mais tarde no final de semana e apresentaram maior sonolência diurna, comparando-se aos que acreditavam dormir o suficiente.

Sleep and weight-height development / Sono e desenvolvimento pondero-estatural

Abstract Objectives: To describe the association between sleep duration and weight-height development in children and adolescents. Source of data: A non-systematic search in the MEDLINE database was performed using the terms anthropometry, body composition, overweight, obesity, body mass index, growth, length, short stature, sleep, children, and infants and adolescents, limited to the last 5 years. The references cited in the revised articles were also reviewed, when relevant. Synthesis of data: Sleep disorders are prevalent in the pediatric population. Among them, insomnia, which leads to a reduction in total sleep time, is the most prevalent disorder. Evidence found in the current literature allows the conclusion that sleep time reduction has a role in the current pandemic of overweight and obesity. Studies associating sleep deprivation and deficit in height growth are still insufficient. Conclusions: The association between shorter sleep duration and risk of overweight and obesity is well established for all pediatric age groups. However, more evidence is needed to establish an association between insufficient sleep duration and height growth deficit. Pediatricians should include the encouragement of healthy sleep habits in their routine guidelines as an adjuvant in the prevention and management of excess weight.

Resumo Objetivos: O objetivo deste artigo é descrever a associac¸ão entre a durac¸ão de sono e o desenvolvimento pondero-estatural entre crianc¸as e adolescentes. Fontes de dados: Foi realizada uma busca não-sistemática na base de dados MEDLINE utilizando os termos antropometria, composic¸ão corporal, sobrepeso, obesidade, índice de massa corporal, crescimento, comprimento, baixa estatura, sono, crianc¸as, lactentes e adolescentes, limitadas aos últimos cinco anos. As referências citadas nos artigos revisados também foram, conforme relevância, revisados. Síntese dos dados: Distúrbios do sono são prevalentes na população pediátrica. Dentre eles, a insônia, que cursa com redução do tempo total de sono, é a mais prevalente. Evidências presentes na literatura atual permitem apontar que a redução do tempo de sono tem um papel na pandemia atual de sobrepeso e obesidade. Os estudos que associam a privação de sono com déficit no crescimento estatural ainda são insuficientes. Conclusões: A associação entre menor duração de sono e risco para sobrepeso e obesidade está bem estabelecida para todas as faixas etárias da pediatria. Entretanto, maiores evidências são necessárias para que se possa estabelecer uma associação entre duração insuficiente de sono e déficit no crescimento estatural. O médico pediatra deve incluir nas suas orientações de rotina o estímulo a hábitos de sono saudáveis como coadjuvante na prevenção e manejo do excesso de peso.

Night work and BMI: is it related to on-shift napping?

ABSTRACT On-shift napping can benefit night workers regarding sleep loss, synchronization of circadian rhythms, and alertness. However, few studies on napping can be found in the literature focused on possible health benefits. This cross-sectional study has investigated the role of on-shift napping on the association between night work and BMI in 409 night-shift nursing professionals. The number of working nights and the years of exposure to night work were significantly associated with increased BMI levels among non-nappers, but not among nappers. Results suggest a benefit of napping for weight gain, thus subsidizing occupational health policies on the regulation of on-shift napping among nursing workers.

Autonomic and Renal Alterations in the Offspring of Sleep-Restricted Mothers During Late Pregnancy

OBJECTIVES: Considering that changes in the maternal environment may result in changes in progeny, the aim of this study was to investigate the influence of sleep restriction during the last week of pregnancy on renal function and autonomic responses in male descendants at an adult age. METHODS: After confirmation of pregnancy, female Wistar rats were randomly assigned to either a control or a sleep restriction group. The sleep-restricted rats were subjected to sleep restriction using the multiple platforms method for over 20 hours per day between the 14th and 20th day of pregnancy. After delivery, the litters were limited to 6 offspring that were designated as offspring from control and offspring from sleep-restricted mothers. Indirect measurements of systolic blood pressure (BPi), renal plasma flow, glomerular filtration rate, glomerular area and number of glomeruli per field were evaluated at three months of age. Direct measurements of cardiovascular function (heart rate and mean arterial pressure), cardiac sympathetic tone, cardiac parasympathetic tone, and baroreflex sensitivity were evaluated at four months of age. RESULTS: The sleep-restricted offspring presented increases in BPi, glomerular filtration rate and glomerular area compared with the control offspring. The sleep-restricted offspring also showed higher basal heart rate, increased mean arterial pressure, increased sympathetic cardiac tone, decreased parasympathetic cardiac tone and reduced baroreflex sensitivity. CONCLUSIONS: Our data suggest that reductions in sleep during the last week of pregnancy lead to alterations in cardiovascular autonomic regulation and renal morpho-functional changes in offspring, triggering increases in blood pressure.

The Effect of Sleep Deprivation on Cardiac Function and Tolerance to Ischemia-Reperfusion Injury in Male Rats / O Efeito da Privação de Sono na Função Cardíaca e Tolerância à Lesão de Isquemia-Reperfusão em Ratos

Abstract Background: Sleep deprivation (SD) is strongly associated with elevated risk for cardiovascular disease. Objective: To determine the effect of SD on basal hemodynamic functions and tolerance to myocardial ischemia-reperfusion (IR) injury in male rats. Method: SD was induced by using the flowerpot method for 4 days. Isolated hearts were perfused with Langendorff setup, and the following parameters were measured at baseline and after IR: left ventricular developed pressure (LVDP); heart rate (HR); and the maximum rate of increase and decrease of left ventricular pressure (±dp/dt). Heart NOx level, infarct size and coronary flow CK-MB and LDH were measured after IR. Systolic blood pressure (SBP) was measured at start and end of study. Results: In the SD group, the baseline levels of LVDP (19%), +dp/dt (18%), and -dp/dt (21%) were significantly (p < 0.05) lower, and HR (32%) was significantly higher compared to the controls. After ischemia, hearts from SD group displayed a significant increase in HR together with a low hemodynamic function recovery compared to the controls. In the SD group, NOx level in heart, coronary flow CK-MB and LDH and infarct size significantly increased after IR; also SD rats had higher SBP after 4 days. Conclusion: Hearts from SD rats had lower basal cardiac function and less tolerance to IR injury, which may be linked to an increase in NO production following IR.

Resumo Fundamento: A privação de sono (PS) acha-se fortemente associada a alto risco cardiovascular. Objetivo: Determinar o efeito da PS nas funções hemodinâmicas basais e tolerância à lesão miocárdica de isquemia‑reperfusão (IR) em ratos machos. Métodos: A PS foi induzida com o método da plataforma única por 4 dias. Utilizou-se o modelo de perfusão de coração isolado de Langendorff, medindo-se os seguintes parâmetros nas condições basais e após IR: pressão desenvolvida no ventrículo esquerdo (PDVE), frequência cardíaca (FC) e taxa máxima de aumento e redução da pressão do ventrículo esquerdo (±dp/dt). O nível cardíaco de NOx, o tamanho do infarto e os níveis de CK-MB e LDH no efluente coronário foram medidos após IR. A pressão arterial sistólica (PAS) foi medida no início e no final do estudo. Resultados: No grupo PS, os valores basais de PDVE (19%), +dp/dt (18%) e-dp/dt (21%) foram significativamente mais baixos (p < 0,05), e a FC (32%) significativamente mais alta em comparação aos dos controles. Após isquemia, os corações do grupo PS apresentavam um significativo aumento da FC além de uma menor recuperação da função hemodinâmica em comparação aos dos controles. No grupo PS, os níveis de NOx no coração e de CK-MB e LDH no efluente coronário, além do tamanho do infarto, foram significativamente maiores após IR. O grupo PS também apresentou maior PAS após 4 dias. Conclusão: Os corações do grupo PS apresentaram menor função cardíaca basal e menor tolerância à lesão de IR, o que pode estar relacionado ao aumento da produção de NO após IR.

Sleep in the intensive care unit / Sono na unidade de terapia intensiva

ABSTRACT Poor sleep quality is a consistently reported by patients in the ICU. In such a potentially hostile environment, sleep is extremely fragmented and sleep architecture is unconventional, with a predominance of superficial sleep stages and a limited amount of time spent in the restorative stages. Among the causes of sleep disruption in the ICU are factors intrinsic to the patients and the acute nature of their condition, as well as factors related to the ICU environment and the treatments administered, such as mechanical ventilation and drug therapy. Although the consequences of poor sleep quality for the recovery of ICU patients remain unknown, it seems to influence the immune, metabolic, cardiovascular, respiratory, and neurological systems. There is evidence that multifaceted interventions focused on minimizing nocturnal sleep disruptions improve sleep quality in ICU patients. In this article, we review the literature regarding normal sleep and sleep in the ICU. We also analyze sleep assessment methods; the causes of poor sleep quality and its potential implications for the recovery process of critically ill patients; and strategies for sleep promotion.

RESUMO O sono de má qualidade é uma situação persistentemente descrita em UTIs. O sono nesse ambiente potencialmente hostil é caracterizado pela sua extrema fragmentação e arquitetura não convencional, com predomínio de fases leves e limitada quantidade de tempo nos estágios reparadores. Entre as causas da privação do sono na UTI estão fatores intrínsecos aos pacientes e à condição aguda de sua doença, assim como fatores relacionados ao ambiente da UTI e ao tratamento em curso, como o suporte ventilatório e a terapia medicamentosa. Embora as consequências da má qualidade do sono no processo de recuperação desses pacientes ainda sejam desconhecidas, ela parece influenciar os sistemas imune, metabólico, cardiovascular, respiratório e neurológico. Evidências sugerem que intervenções multifacetadas, focadas na minimização das perturbações do sono noturno, promovem melhora na qualidade do sono nesses pacientes. Este artigo revisa a literatura acerca do sono normal e do sono na UTI. Também analisa seus métodos de avaliação, as causas da má qualidade do sono, suas potenciais implicações no processo de recuperação de pacientes críticos e estratégias para sua promoção.

Effects of REM sleep restriction during pregnancy on rodent maternal behavior

Objective: To evaluate the effects of sleep restriction during pregnancy on maternal care and maternal aggression in a rodent model. Methods: Twenty-three female Wistar rats were assigned to one of two groups: control (n=12) or sleep restriction (n=11) during the entire pregnancy. At the fifth postpartum day, the animals were subjected to the resident-intruder paradigm and to the pup retrieval test. Results: Sleep restriction during pregnancy had no direct effects on maternal care. Regarding aggressive behavior, defensive aggression was increased by sleep loss, with a lower responsiveness threshold to hostile environmental stimuli. Sleep deprivation during gestation also reduced self-grooming behavior. Conclusion: Taking increased self-grooming as a behavioral correlate of anxiety in rodents, this study provides evidence that lactating dams were in a condition of reduced anxiety. From an adaptive perspective, this pattern of stress response may function to ensure proper maternal behavior, thereby guaranteeing the survival and viability of the litter. Under a translational perspective, the present article confronts the importance of biological and adaptive features to rodent maternal behavior with the relevance of sociocultural factors to the human mother-infant relationship and to the onset of postpartum depression.

Follow-up of obstructive sleep apnea in children / Acompanhamento clínico de crianças com distúrbios respiratórios do sono

INTRODUCTION: the evolution of snoring and OSAS in children is not well established since few studies of patients without surgical treatment have been published. OBJECTIVE: to evaluate the evolution of sleep disordered breathing in children who had not been submitted to upper airway surgery. METHOD: twenty-six children with snoring who had not undergone upper airway surgery were evaluated prospectively. Patients were evaluated by full physical examination and nocturnal polysomnography, after which they were divided into 2 groups: apnea (16 children) and snoring (10 children). After 6 months following the initial evaluation, patients were submitted to a new nocturnal polysomnography, and all data were compared to those of the first examination. RESULTS: the groups did not show any differences regarding age, weight, height and airway physical examination. After 6 months of follow-up, the apnea index did not change, but the respiratory disturbance index increased in the snoring group and the number of hypopneas decreased in the group apnea. CONCLUSION: there was an increase in the percentage of N1 sleep stage and the respiratory disturbance index in the patients with primary snore. The AHI did not show significant alteration in both groups, but the number of hypopneas decreased in patients with SAOS. .

INTRODUÇÃO: a evolução do ronco e da síndrome da apneia/hipoapneia obstrutiva do sono (SAOS) na infância ainda não está bem estabelecida e poucos estudos desses pacientes sem o tratamento cirúrgico foram publicados. OBJETIVO: avaliar a evolução da apneia e do ronco primário em crianças que não foram submetidas a cirurgia das vias aéreas superiores. MÉTODOS: foram avaliadas prospectivamente 26 crianças com ronco que não haviam sido submetidas a tratamento cirúrgico. Todas foram submetidas a exame físico, nasofibroscopia e polissonografia, a partir dos quais foram divididos em dois grupos: SAOS (16 crianças) e ronco (10 crianças). Após 6 meses da avaliação inicial, os exames foram repetidos, e os dados encontrados foram comparados. RESULTADOS: os grupos não apresentaram diferença entre si comparando idade, peso, altura e exame físico. Quando comparamos os resultados das duas polissonografias, houve um aumento da porcentagem do estágio do sono N1 no grupo ronco. O índice de apneia/hipoapnéeia (IAH) não apresentou alteração em ambos os grupos, o índice de distúrbios respiratórios (IDR) aumentou no grupo ronco, e o número de hipopneias diminuiu no grupo SAOS. CONCLUSÃO: houve aumento da porcentagem do estágio 1 do sono não-REM e do IDR nos pacientes com ronco primário; o IAH não apresentou alteração significante; o número de hipoapneias diminuiu nos pacientes com SAOS. .

The influence of sleep deprivation and obesity on DNA damage in female Zucker rats

OBJECTIVE: The aim of this study was to evaluate overall genetic damage induced by total sleep deprivation in obese, female Zucker rats of differing ages. METHOD: Lean and obese Zucker rats at 3, 6, and 15 months old were randomly distributed into two groups for each age group: home-cage control and sleep-deprived (N = 5/group). The sleep-deprived groups were deprived sleep by gentle handling for 6 hours, whereas the home-cage control group was allowed to remain undisturbed in their home-cage. At the end of the sleep deprivation period, or after an equivalent amount of time for the home-cage control groups, the rats were brought to an adjacent room and decapitated. The blood, brain, and liver tissue were collected and stored individually to evaluate DNA damage. RESULTS: Significant genetic damage was observed only in 15-month-old rats. Genetic damage was present in the liver cells from sleep-deprived obese rats compared with lean rats in the same condition. Sleep deprivation was associated with genetic damage in brain cells regardless of obesity status. DNA damage was observed in the peripheral blood cells regardless of sleep condition or obesity status. CONCLUSION: Taken together, these results suggest that obesity was associated with genetic damage in liver cells, whereas sleep deprivation was associated with DNA damage in brain cells. These results also indicate that there is no synergistic effect of these noxious conditions on the overall level of genetic damage. In addition, the level of DNA damage was significantly higher in 15-month-old rats compared to younger rats.

Relationship between sleep deprivation and anxiety: experimental research perspective / Relação entre privação de sono e ansiedade na pesquisa básica

Sleep deprivation is a condition that is more and more observed in modern society bringing various neurobehavioral effects, being anxious states one of the main problems. Many studies have successfully demonstrated the relationship between sleep deprivation and anxiety in clinical research. As to basic experimentation, various models have been efficiently used in order to evaluate an anxious behavior. However, the same efficacy is not found on basic studies that deal with the relationship between paradoxical sleep and anxiety. The great majority of studies which approach this matter in animal models do not present results that may be applied to clinical practice and this is basically due to two reasons: inconsistency among results and lack of replicability as related to clinical studies. It has to be emphasized that the use of animal models is extremely useful, mainly under experimental conditions which cannot be ethically or plausibly be approached in human beings. So, the present theoretical assay tries to evaluate in a brief and critical manner the applicability of animal models in sleep deprivation under a translational perspective.

A privação de sono é uma condição cada vez mais observada na sociedade moderna, resultando em diversos efeitos neurocomportamentais. Um dos principais efeitos comportamentais dessa condição é a proeminência de estados ansiosos. Diversos estudos têm demonstrado, com sucesso, a relação entre privação de sono e ansiedade na pesquisa clínica. Quanto à experimentação básica, diversos modelos têm sido eficientemente empregados na avaliação do comportamento do tipo ansioso. Todavia, a mesma eficácia não é encontrada nos estudos básicos, que abordam a relação entre privação de sono paradoxal e ansiedade. A maioria dos estudos que aborda essa relação em modelos animais não apresenta resultados passíveis de extrapolação à prática clínica, e isso se deve basicamente a dois motivos: inconsistência entre resultados e falta de replicabilidade em relação a estudos clínicos. Ressalta-se que o uso de modelo animais é extremamente útil, sobretudo em condições experimentais que não podem ser ética ou plausivelmente abordadas em seres humanos. Desse modo, o presente ensaio teórico busca avaliar, de modo sucinto e crítico, a aplicabilidade dos modelos animais de privação de sono, sob uma perspectiva translacional.

Impacto que tiene la falta de sueño sobre las habilidades cognitivas de una población de estudiantes de medicina / Impact of sleep deprivation on the cognitive abilities of a population of medical students

Los estudiantes que ingresan a la Escuela de Medicina son personas que pasarán los próximos años de su vida preparándose para entender la composición, la anatomía y la fisiología tanto normal como patológica del cuerpo humano con el fin de luego, aplicar ese conocimiento en el tratamiento de sus pacientes. Sin embargo, ser estudiante de Medicina se ha descrito como un extenuante proceso en el cual los jóvenes sufren alteraciones notables en sus horas de sueño, niveles de estrés, presión y fustración emocional e incluso depresión. Esta investigación se llevó a cabo para identificar en una población de estudiantes de segundo semestre de segundo año de Medicina de la Universidad de Costa Rica, el deterioro cognitivo que puede tener dicho estilo de vida y cómo influye en la capacidad de aprendizaje y los resultados que estos pueden obtener. A través de la figura compleja de Rey-Osterrieth y la prueba MoCA (Montreal Cognitive Assesment) se evaluó la muestra en dos oportunidades distintas: al encontrarse los estudiantes en un período de evaluación normal y con un nivel de cansancio notable tras un período de evaluación más intenso. Los datos obtenidos comprobaron que efectivamente existe un deterioro en el rendimiento y las capacidades cognitivas de los jóvenes...

Influence of food restriction on lipid profile and spontaneous glucose levels in male rats subjected to paradoxical sleep deprivation

OBJECTIVES: The purpose of this study was to determine the paired consequences of food restriction and paradoxical sleep deprivation on lipid profile and spontaneous glucose levels in male rats. METHOD: Food restriction began at weaning, with 6 g of food being provided per day, which was subsequently increased by 1 g per week until reaching 15 g per day by the eighth week. At adulthood, both rats subjected to food restriction and those fed ad libitum were exposed to paradoxical sleep deprivation for 96 h or were maintained in their home-cage groups. RESULTS: Animals subjected to food restriction exhibited a significant increase in high-density lipoprotein levels compared to animals that were given free access to food. After the paradoxical sleep deprivation period, the foodrestricted animals demonstrated reduced concentrations of high-density lipoprotein relative to their respective controls, although the values for the food-restricted animals after sleep deprivation were still higher than those for the ad libitum group. The concentration of low-density lipoproteins was significantly increased in sleep-deprived animals fed the ad libitum diet. The levels of triglycerides, very low-density lipoproteins, and glucose in foodrestricted animals were each decreased compared to both ad libitum groups. CONCLUSION: These results may help to illustrate the mechanisms underlying the relationship between sleep curtailment and metabolism and may suggest that, regardless of sleep deprivation, dietary restriction can minimize alterations in parameters related to cardiovascular risk.

La reducción del sueño como factor de riesgo para obesidad / Sleep deprivation as a risk factor for obesity

Nocturnal sleep patterns may be a contributing factor for the epidemic of obesity. Epidemiologic ana experimental studies have reported that sleep restriction is an independent risk factor for weight gain and obesity. Moreover, sleep restriction is significantly associated with incidence and prevalence of obesity and several non-transmissible chronic diseases. Experimental sleep restriction is related to altered plasma leptin and ghrelin concentrations. Both hormones are directly related to appetite and satiety mechanisms. Also, a higher activity of the orexin/hypocretin system has been reported, as well as changes in glucose metabolism and autonomic nervous system. Some studies indicate that these endocrine changes could be associated with a higher diurnal food intake and preference for energy- dense foods. All these changes could result in a positive energy balance, leading to weight gain and a higher obesity risk in the long-term. The present article summarizes the epidemiologic and experimental evidence related to sleep deprivation and higher obesity risk. The possible mechanisms are highlighted.

Effects of Posture and Acute Sleep Deprivation on Heart Rate Variability

PURPOSE: In our previous study to investigate autonomic nervous system (ANS) activity due to radio frequency (RF) radiation using heart rate variability (HRV), drowsiness was observed in approximately half of all subjects. Therefore, the usage of HRV with unwanted drowsiness could falsely indicate the effects of RF radiation by mobile phones on the ANS. The objective of this study was to determine which posture is appropriate for accurate HRV analysis for provocation study. MATERIALS AND METHODS: A total of 52 healthy subjects (25 males and 27 females) participated in this experiment. We measured the number of times a subject showed drowsiness or sleep deprivation due to awakening, and analyzed HRV six times over 30 minutes in sitting and recumbent postures, using power spectrum. RESULTS: We employed the ratio of low frequency power to high frequency power (LFP/HFP) to analyze the changes in the ANS. The number of sleep deprivation occurrences in the sitting posture was significantly less than that in the recumbent posture (p<0.01), resulting in smaller increase of LFP/HFP. Although LFP/HFP of the two postures varied with time without any provocation, it was more stable in sitting than in recumbent postures. CONCLUSION: A sitting posture is preferable to a recumbent posture for analyzing HRV, because of decreased drowsiness and sleep deprivation, thereby decreasing variation of LFP/HFP during experiment. Considering the drowsiness, it is also recommended that any experiment should be completed within 15 minutes, if possible.

Paradoxical sleep deprivation: neurochemical, hormonal and behavioral alterations: evidence from 30 years of research

Sleep comprises approximately one-third of a person's lifetime, but its impact on health and medical conditions remains partially unrecognized. The prevalence of sleep disorders is increasing in modern societies, with significant repercussions on people's well-being. This article reviews past and current literature on the paradoxical sleep deprivation method as well as data on its consequences to animals, ranging from behavioral changes to alterations in the gene expression. More specifically, we highlight relevant experimental studies and our group's contribution over the last three decades.

O sono ocupa cerca de um terço de nossas vidas, entretanto seu impacto na saúde e sua influência nas condições patológicas ainda não foi completamente elucidado. A prevalência dos distúrbios de sono é cada vez maior, sobretudo nas regiões mais industrializadas, repercutindo diretamente no bem-estar da população. Este artigo tem como objetivo sintetizar e atualizar a literatura a respeito do método de privação de sono paradoxal e seu panorama de conseqüências desde comportamentais até genéticas em animais. Ainda, destacamos a contribuição e relevância dos estudos experimentais realizados por nosso grupo nas ultimas três décadas.

On-line analysis of biosignals for the automation of total and specific sleep deprivation in the rat

A computer-based system that automates sleep studies, including sleep deprivation paradigms, is described. The system allows for total or REM-specific sleep deprivation and is based on a reliable, fast-responding, on-line state detection algorithm linked to a dependable intervention device. Behavioral state detection is achieved by dimension reduction of short-term EEG power spectrum. Interventions are made by serial outputs to servomotors that move a cage with different patterns and variable intensity. The system can adapt itself to individual characteristics and to changes in recording conditions. Customized protocols can be designed by defining the states or stages to be deprived, including scheduling temporal patterns. A detailed analysis of the relevant signals during and after deprivation is readily available. Data is presented from two experimental designs in rats. One consisted of specific REM-sleep short-term deprivation and the other of 10-hour total sleep deprivation. An outline of conceptual and practical considerations involved in the automation of laboratory set-ups oriented to biosignal analysis is provided. Careful monitoring of sleep EEG variables during sleep deprivation suggests peculiarities of brain functioning in that condition. A corollary is that sleep deprivation should not be considered to be merely a forced prolonged wakefulness.

Influence of gender on psychomotor vigilance task performance by adolescents

During adolescence, the sleep phase delay associated with early school times increases daytime sleepiness and reduces psychomotor performance. Some studies have shown an effect of gender on psychomotor performance in adults and children. Males present faster reaction times (RT) compared with females. The aim of the present study was to evaluate the influence of gender on Palm psychomotor vigilance task (PVT) performance in adolescents. Thirty-four adolescents (19 girls, 13 to 16 years old) attending morning school classes of a public school in Curitiba, PR, Brazil, participated in the study. Sleep patterns were measured using actigraphy and sleepiness data were accessed with the Karolinska Sleepiness Scale (KSS). KSS and PVT measurements were collected at two times in the morning (8:00 and 11:00 h). The data were compared using one-way ANOVA, considering gender as a factor. ANOVA indicated that gender did not affect sleep patterns and subjective somnolence; however, a statistically significant effect of gender was detected for PVT performance. Boys presented faster RT (RT-PVT1: 345.51 ms, F = 6.08, P < 0.05; RT-PVT2: 343.30 ms, F = 6.35, P < 0.05) and fewer lapses (lapses-PVT1: 8.71, F = 4.45, P < 0.05; lapses-PVT2: 7.82, F = 7.06, P < 0.05) compared with girls (RT-PVT1: 402.96; RT-PVT2: 415.70; lapses-PVT1: 16.33; lapses-PVT2: 17.80). These results showed that this effect of gender, already reported in adults and children, is also observed in adolescents. The influence of gender should be taken into account in studies that use Palm PVT to evaluate psychomotor performance in this age range.

Effects of cocaine, methamphetamine and modafinil challenge on sleep rebound after paradoxical sleep deprivation in rats

Sleep loss is both common and critically relevant to our society and might lead to the abuse of psychostimulants such as amphetamines, cocaine and modafinil. Since psychoactive substance abuse often occurs within a scenario of sleep deficit, the purpose of this investigation was to compare the sleep patterns of rats challenged with cocaine (7 mg/kg, ip), methamphetamine (7 mg/kg, ip), or modafinil (100 mg/kg, ip) subsequent to paradoxical sleep deprivation (PSD) for 96 h. Our results show that, immediately after 96 h of PSD, rats (10 per group) that were injected with a psychostimulant presented lower percentages of paradoxical sleep compared to those injected with saline (P < 0.01). Regarding slow wave sleep (SWS), rats injected with psychostimulants after PSD presented a late rebound (on the second night subsequent to the injection) in the percentage of this phase of sleep when compared to PSD rats injected with saline (P < 0.05). In addition, the current study has produced evidence of the characteristic effect of each drug on sleep architecture. Home cage control rats injected with modafinil and methamphetamine showed a reduction in SWS compared with the saline group. Methamphetamine affected sleep patterns most, since it significantly reduced paradoxical sleep, SWS and sleep efficiency before and after PSD compared to control (P < 0.05). Cocaine was the psychostimulant causing the least changes in sleep pattern in relation to those observed after saline injection. Therefore, our results suggest that abuse of these psychostimulants in a PSD paradigm aggravates their impact on sleep patterns.

Effect of sildenafil (Viagra®) on the genital reflexes of paradoxical sleep-deprived male rats

Since there is evidence that paradoxical sleep deprivation (PSD) elicits penile erection (PE) and ejaculation (EJ), and that the erectile response of rats is mediated by nitric oxide, the present study sought to extend the latter finding by assessing the effects of sildenafil on the genital reflexes of male Wistar rats subjected to PSD. We also determined the influence of sildenafil on hormone concentrations. In the first experiment, sildenafil at doses ranging from 0.08 to 0.32 mg/kg was administered intraperitoneally to rats that had been deprived of sleep for 4 days and to home cage controls (N = 8-10/group). The frequency of PE and EJ was measured for 60 min. PSD alone induced PE in 50 percent of the animals; however, a single injection of sildenafil did not significantly increase the percentage of rats displaying PE compared to PSD-saline or to home cage groups. PSD alone also induced spontaneous EJ, but this response was not potentiated by sildenafil in the dose range tested. Testosterone concentrations were significantly lower in PSD rats (137 ± 22 ng/dL) than in controls (365 ± 38 ng/dL), whereas progesterone (0.9 ± 0.1 vs 5.4 ± 1 ng/mL) and plasma dopamine (103.4 ± 30 vs 262.6 ± 77 pg/mL) increased. These changes did not occur after sildenafil treatment. The data show that although sildenafil did not alter the frequency of genital reflexes, it antagonized hormonal (testosterone and progesterone) and plasma dopamine changes induced by PSD. The stimulation of the genital reflexes by sildenafil did not result in potentiating effects in PSD rats.

Pontas positivas occipitais transitórias no eletrencefalograma de pacientes epilépticos submetidos a privação do sono / Sleep occipital positive transient spikes seen at EEG of epileptic patients submitted to sleep deprivation

OBJETIVO: Comparar o aparecimento do grafoelemento de ponta positiva occipital transitória do sono em eletrencefalograma (EEG) de pacientes epilépticos com e sem privação do sono, como método de ativação. MÉTODO: Foram analisados 40 EEG de 20 pacientes epilépticos com idade variando de 12 a 43 anos sendo 60 por cento do sexo masculino, atendidos no Hospital das Clínicas da Universidade Federal de Pernambuco, no período de 1995 a 2000. Foram incluídos pacientes com epilepsia diagnosticada clinicamente e EEG sem alteração. Cada paciente foi submetido a um EEG sem privação de sono e outro após 36 horas de privação. O registro dos dois EEG foi separado por intervalo de 48 horas, obedecendo ao protocolo padrão. O efeito da privação do sono foi avaliado pelo aparecimento do grafoelemento PPOTS durante o estágio NREM do sono. RESULTADOS: No EEG sem privação do sono, a PPOTS foi identificada em 6 (30 por cento) pacientes no estágio I e em 1 (5 por cento) paciente em ambos os estágios I e II NREM. Após privação do sono, PPOTS estiveram ausentes em apenas um paciente, mas presentes em 25 por cento casos no estágio I NREM e em 70 por cento, nos estágios I e II NREM. CONCLUSÃO: O aumento da freqüência de PPOTS após privação do sono, parece indicar a existência da liberação de neurotransmissores excitatórios, o que pode contribuir significativamente para a investigação da excitabilidade cerebral.

OBJECTIVE: To compare the presence of "sleep occipital positive transient spikes" (SOPTS) in the electroencephalogram (EEG) of epileptic patients without sleep deprivation (SD) to those with SD, as an activation method. METHOD: The author analyzed 40 EEG of 20 epileptic patients, aging from 12 to 43 years, 60 percent, males. Those patients were attempted at the Clinics Hospital of Universidade Federal de Pernambuco, from 1995 to 2000. Every patient included in this study had epilepsy clinically diagnosed and all EEG without abnormalities. Each subject was submitted to one EEG without SD and another, after 36 hours of SD. The register of these EEG was performed within an interval of 48 h, obeying to the standard protocol. The effect of sleep deprivation was evaluated by the presence of the graphic element SOPTS during NREM sleep stage. RESULTS: On the EEG without SD, the SOPTS were present in 6 (30 percent) patients on stage I and in 1 (5 percent) other, on both stages I and II NREM. After SD, SOPTS were absent for only one patient, but were identified on stage I NREM for 25 percent of patients and, on stages I and II NREM, for 75 percent of cases. CONCLUSION: The increase on the frequency of SOPTS after sleep deprivation seems to indicate the existence of excitatory neurotransmitters, what may significantly contribute to the investigation of cerebral excitability.