The concept of the immune-pineal axis tested in patients undergoing an abdominal hysterectomy.

OBJECTIVE: Activation of the immune-pineal axis induces a transient reduction in nocturnal melatonin in the plasma during the proinflammatory phase of an innate immune response to allow the proper migration of leukocytes to the lesion site. This transient reduction should be regulated by inflammatory mediators, which are responsible for the fine-tuning of the process. In the present study, we measured the pre- and postoperative serum concentrations of melatonin, tumor necrosis factor (TNF) and cortisol in women who underwent an elective hysterectomy and correlated the variation in melatonin with postoperative pain. METHODS: We evaluated 12 women who had an abdominal hysterectomy. Blood was collected at 10.00 and 22.00 h 1 week and 1 day before the surgery, on the 1st and 2nd days after the surgery and at 22.00 h on the day of the surgery. RESULTS: On the night after the surgery, there was no melatonin detected at 22.00 h. High TNF levels were accompanied by a lower nocturnal melatonin output, higher postoperative pain according to a visual analog scale and the request of higher doses of analgesics. In addition, low cortisol levels were accompanied by a lower nocturnal melatonin output. CONCLUSION: Our results confirm that the same antagonistic pattern between TNF and glucocorticoids observed in cultured pineal glands also occurs in humans. This integrative pattern suggests that the cross talk between the immune and endocrine system orchestrates longitudinal changes in pineal activity, reinforcing the hypothesis of an immune-pineal axis.

The effect of sunlight exposure on interleukin-6 levels in depressive and non-depressive subjects.

BACKGROUND: The objective of this epidemiological study was to evaluate the effect of length of sunlight exposure on interleukin 6 (IL-6) levels in depressive and non-depressive subjects. METHODS: This was a cross-sectional study with 154 subjects (54 males, mean age: 43.5 ± 12.8 years) who were living in a rural area in south Brazil. Chronobiological and light parameters were assessed using the Munich Chronotype Questionnaire. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index. Depressive symptoms were assessed with the Beck Depression Inventory. Plasma levels of inflammatory cytokines (IL-2, IL-4, IL-6, IL-10, tumor necrosis factor-α, and interferon) were collected during the daytime and measured. RESULTS: IL-6 levels showed a positive correlation with light exposure (r = 0.257; p < 0.001) and a negative correlation with the mid-sleep phase on work-free days (r = -0.177; p = 0.028). Multiple linear regression analysis showed that only the length of light exposure was an independent factor for predicting IL-6 levels (ß = 0.26; p = 0.002). In non-depressed subjects, exposure to a different intensity of light did not affect IL-6 levels (t = -1.6; p = 0.1). However, when the two depressive groups with low and high light exposure were compared, the low light exposure group had lower levels of IL-6 compared with the high light exposure group (t = -2.19 and p = 0.0037). CONCLUSIONS: The amount of time that participants are exposed to sunlight is directly related to their IL-6 levels. Additionally, depressed subjects differ in their IL-6 levels if they are exposed to light for differing amounts of time.

A new chronobiological approach to discriminate between acute and chronic depression using peripheral temperature, rest-activity, and light exposure parameters.

BACKGROUND: Circadian theories for major depressive disorder have suggested that the rhythm of the circadian pacemaker is misaligned. Stable phase relationships between internal rhythms, such as temperature and rest/activity, and the external day-night cycle, are considered to be crucial for adapting to life in the external environmental. Therefore, the relationship and possible alterations among (i) light exposure, (ii) activity rhythm, and (iii) temperature rhythm could be important factors in clinical depression. This study aimed to investigate the rhythmic alterations in depression and evaluate the ability of chronobiological parameters to discriminate between healthy subjects and depressed patients. METHODS: Thirty female subjects, including healthy subjects, depressed patients in the first episode, and major recurrent depression patients. Symptoms were assessed using Hamilton Depression Scale, Beck Depression Inventory and Montgomery-Äsberg Scale. Motor activity, temperature, and light values were determined for 7 days by actigraph, and circadian rhythms were calculated. RESULTS: Depressed groups showed a lower amplitude in the circadian rhythm of activity and light exposure, but a higher amplitude in the rhythm of peripheral temperature. The correlation between temperature and activity values was different in the day and night among the control and depressed groups. For the same level of activity, depressed patients had lowest temperature values during the day. The amplitudes of temperature and activity were the highest discriminant parameters. CONCLUSIONS: These results indicate that the study of rhythms is useful for diagnosis and therapy for depressive mood disorders.

Morningness-eveningness, use of stimulants, and minor psychiatric disorders among undergraduate students.

Morningness-eveningness dimension in humans have been indicated to influence social behavior and individual health. The aim of the present study was to investigate the association of the morningness-eveningness dimension with behavioral and health aspects in a sample of undergraduate students. We assessed demographic data; the Pittsburgh Sleep Quality Index was used to evaluate sleep quality; the Morningness/Eveningness Questionnaire to determine morningness-eveningness, and the Self-Reporting Questionnaire to assess minor psychiatric disorders. A total of 372 students (66.7% females), on average 21.6 years old, participated in this study. Among them, 92.2% did not smoke, 58.9% engaged in physical activities, and 19.7% were night-shift workers. In regard to morningness-eveningness, 55.9% of the participants were intermediate between evening (39.5%) and morning (4.6%) types. Poor sleep quality (OR = 1.89), minor psychiatric disorders (OR = 1.92), and tobacco consumption (OR = 3.65) predominated among evening types. Evening types were predominantly males (OR = 1.72). This study suggests that evening types are more vulnerable to sleep and psychiatric disturbances, and tend to smoke more than morning types.

[Clinical Protocol of the Brazilian Ministry of Health on Parkinson's Disease: adherence and perception of the prescribing physician]. / Protocolo Clínico do Ministério da Saúde/Brasil para Doença de Parkinson: adesão e percepção do médico prescritor.

This study evaluated the adherence of physicians to the Clinical Protocol and Therapeutic Guidelines on Parkinson's Disease (CPTG-PD) within the scope of the Unified Health System (SUS). A descriptive analysis of 375 drug application documents sent to the Pharmaceutical Services of the Rio Grande do Sul State Public Health Department (AF/SES/RS) between March and September 2016, and a structured survey to evaluate the physician's perception about the protocol and barriers to its use was conducted. Only 5.33% of the requests analyzed presented all the necessary data, considering the criteria of the protocol. The requests from specialists had a higher percentage of adherence to the diagnostic and dose criteria (p<0.05). The main barriers to protocol use were the lack of awareness or familiarity with the protocol (48%) and the lack of time to complete the mandatory documents (52%). More recently qualified physicians tended to perceive fewer barriers to protocol use (p<0.05). The results indicate that actions are still necessary to implement the PCDT-DP in medical practice, focusing on care and management teams. Greater integration between pharmaceutical assistance and the healthcare network is needed.

Este estudo avaliou a adesão de médicos ao Protocolo Clínico e Diretrizes Terapêuticas para a Doença de Parkinson (PCDT-DP), no âmbito do SUS. Dois métodos complementares foram utilizados: avaliação descritiva de 375 solicitações de medicamentos encaminhadas à Assistência Farmacêutica da Secretaria de Estado da Saúde do Rio Grande do Sul, de março a setembro de 2016, e levantamento por meio de questionário estruturado aos prescritores para investigar a percepção de barreiras à utilização. Apenas 5,33% das solicitações analisadas apresentaram adesão completa às recomendações do protocolo. As solicitações oriundas de especialistas em DP tiveram maior adesão aos critérios para o diagnóstico (p<0,05) e dose do medicamento (p<0,05). Dentre as respostas ao questionário destacaram-se como principais barreiras a falta de tempo para preenchimento dos documentos obrigatórios (52%) e nenhum ou pouco conhecimento sobre o protocolo (48%). Médicos com menor tempo de exercício de profissão tendem a perceber menos barreiras para a utilização do protocolo (p<0,05). Os resultados indicam a necessidade de ações de implementação do PCDT-DP à prática médica, direcionadas às equipes assistenciais e de gestão, e maior integração da assistência farmacêutica com a rede de atenção.

Relationship Between Circadian Strain, Light Exposure, and Body Mass Index in Rural and Urban Quilombola Communities.

Industrialization has greatly changed human lifestyle; work and leisure activities have been moved indoors, and artificial light has been used to illuminate the night. As cyclic environmental cues such as light and feeding become weak and/or irregular, endogenous circadian systems are increasingly being disrupted. These disruptions are associated with metabolic dysfunction, possibly contributing to increased rates of overweight and obesity worldwide. Here, we aimed to investigate how activity-rest rhythms, patterns of light exposure, and levels of urbanization may be associated with body mass index (BMI) in a sample of rural and urban Quilombola communities in southern Brazil. These are characterized as remaining social groups who resisted the slavery regime that prevailed in Brazil. Quilombola communities were classified into five groups according to their stage of urbanization: from rural areas with no access to electricity to highly urbanized communities. We collected anthropometric data to calculate BMI, which was categorized as follows: from ≥ 18.5 kg/m2 to < 25 kg/m2 = normal weight; from ≥ 25 kg/m2 to < 30 kg/m2 = overweight; and ≥ 30 kg/m2 = obese. Subjects were asked about their sleep routines and light exposure on workdays and work-free days using the Munich Chronotype Questionnaire (N = 244 included). In addition, we analyzed actimetry data from 121 participants with seven consecutive days of recordings. Living in more urbanized areas and higher intradaily variability (IV) of activity-rest rhythms were associated with an increased risk of belonging to the overweight or obese group, when controlling for age and sex. These findings are consistent with preclinical data and point to potential strategies in obesity prevention and promotion of healthy metabolic profiles.

Circadian Strain, Light Exposure, and Depressive Symptoms in Rural Communities of Southern Brazil.

Irregular light-dark cycles and circadian/sleep disturbances have been suggested as risk or co-occurring factors in depression. Among a set of metrics developed to quantify strain on the circadian system, social jetlag (SJL) has been put forward as a measure of the discrepancy between biological and social clocks. Here, we approached the question on whether light exposure and SJL would also be associated with depressive symptoms in Quilombola communities in Southern Brazil. These rural communities are void of potential confounders of modern lifestyles and show low levels of SJL. 210 Quilombolas (age range 16-92; 56% women) were asked about their sleep times and light exposure using the Munich ChronoType Questionnaire (MCTQ). The Beck Depression Inventory (BDI) was used to assess depressive symptoms. Additionally, we analyzed 7-day actimetry recordings in 124 subjects. BDI scores higher than 10 (having clinically significant depressive symptoms; controlled for age and sex in the multivariate analysis) were positively associated with SJL >1 h and negatively associated with median light exposure during the day, especially in the morning from 8:00 to 10:00. Our results suggest that low light exposure during the day, and higher levels of SJL are associated with depressive symptoms; longitudinal and experimental studies are needed to understand the underlying mechanisms. Nevertheless, we highlight the potential of treatment strategies aimed at decreasing circadian strain and insufficient light exposure, which are suggested as areas of further research in Psychiatry.

Sleep and light exposure across different levels of urbanisation in Brazilian communities.

Quilombos are settlements originally founded by Africans and African descendants (Quilombolas) in remote parts of Brazil to escape slavery. Due to individual histories, Quilombos nowadays exhibit different states of industrialisation, making them ideal for studying the influence of electrification on daily behaviour. In a comparative approach, we aimed to understand whether and how human sleep changes with the introduction of artificial light. We investigated daily rest-activity-rhythms and sleep-patterns in the Quilombolas' by both wrist actimetry and the Munich ChronoType Questionnaire (MCTQ; the results of these two instruments correlated highly). Seven communities (MCTQ: N = 213/actimetry: N = 125) were compared in this study. Light exposure, phase of activity, sleep timing and duration differ across communities with various levels of urbanisation and histories of access to electricity. People living without electricity and those, who acquired it only very recently on average sleep earlier than those in more urbanised communities (mid-sleep about 1 hour earlier); sleep duration tends to be longer. Our results and those of others show that use of electricity and modern lifestyles have changed sleep behaviour. To understand the consequences of these changes for health, further studies are warranted.

Physical self-efficacy is associated to body mass index in schoolchildren.

OBJECTIVE: The present study aimed to investigate the relationship between physical self-efficacy and body mass index in a large sample of schoolchildren. METHODS: The Perceived Physical Ability Scale for Children was administered to 1560 children (50.4% boys; 8-12 years) from three different countries. Weight and height were also recorded to obtain the body mass index. RESULTS: In agreement with the literature, the boys reported greater perceived physical self-efficacy than girls. Moreover, the number of boys who are obese is double that of girls, while the number of boys who are underweight is half that found in girls. In the linear regression model, the increase in body mass index was negatively related to the physical self-efficacy score, differently for boys and girls. Furthermore, age and nationality also were predictors of low physical self-efficacy only for girls. CONCLUSION: The results of this study reinforce the importance of psychological aspect of obesity, as the perceived physical self-efficacy and body mass index were negatively associated in a sample of schoolchildren for boys and girls.

Nocturnal motor activity and light exposure: Objective actigraphy-based marks of melancholic and non-melancholic depressive disorder. Brief report.

Differentiation of melancholic (MEL) and non-melancholic (N-MEL) depression results from subjective assessment of psychomotor disturbance, which obscures their accurate diagnosis. CORE instrument assigned participants with severe or refractory depression to MEL or N-MEL group. Participants underwent 7 days of actigraphy. Data was fitted to a cosinusoidal curve corresponding to a 24-h rhythm. Nocturnal activity was significantly higher in N-MEL. ROC curve shows that average night activity discriminate participants with 71% sensitivity and 100% specificity (area under the curve = 0.84). Actigraphy contribute to the objective differentiation of depression subtypes, and have implications for research on their neurobiology and clinical management.

Identifying pathways modulating sleep duration: from genomics to transcriptomics.

Recognizing that insights into the modulation of sleep duration can emerge by exploring the functional relationships among genes, we used this strategy to explore the genome-wide association results for this trait. We detected two major signalling pathways (ion channels and the ERBB signalling family of tyrosine kinases) that could be replicated across independent GWA studies meta-analyses. To investigate the significance of these pathways for sleep modulation, we performed transcriptome analyses of short sleeping flies' heads (knockdown for the ABCC9 gene homolog; dSur). We found significant alterations in gene-expression in the short sleeping knockdowns versus controls flies, which correspond to pathways associated with sleep duration in our human studies. Most notably, the expression of Rho and EGFR (members of the ERBB signalling pathway) genes was down- and up-regulated, respectively, consistently with the established role of these genes for sleep consolidation in Drosophila. Using a disease multifactorial interaction network, we showed that many of the genes of the pathways indicated to be relevant for sleep duration had functional evidence of their involvement with sleep regulation, circadian rhythms, insulin secretion, gluconeogenesis and lipogenesis.

Protocolo Clínico do Ministério da Saúde/Brasil para Doença de Parkinson: adesão e percepção do médico prescritor / Clinical Protocol of the Brazilian Ministry of Health on Parkinson's Disease: adherence and perception of the prescribing physician

Resumo Este estudo avaliou a adesão de médicos ao Protocolo Clínico e Diretrizes Terapêuticas para a Doença de Parkinson (PCDT-DP), no âmbito do SUS. Dois métodos complementares foram utilizados: avaliação descritiva de 375 solicitações de medicamentos encaminhadas à Assistência Farmacêutica da Secretaria de Estado da Saúde do Rio Grande do Sul, de março a setembro de 2016, e levantamento por meio de questionário estruturado aos prescritores para investigar a percepção de barreiras à utilização. Apenas 5,33% das solicitações analisadas apresentaram adesão completa às recomendações do protocolo. As solicitações oriundas de especialistas em DP tiveram maior adesão aos critérios para o diagnóstico (p<0,05) e dose do medicamento (p<0,05). Dentre as respostas ao questionário destacaram-se como principais barreiras a falta de tempo para preenchimento dos documentos obrigatórios (52%) e nenhum ou pouco conhecimento sobre o protocolo (48%). Médicos com menor tempo de exercício de profissão tendem a perceber menos barreiras para a utilização do protocolo (p<0,05). Os resultados indicam a necessidade de ações de implementação do PCDT-DP à prática médica, direcionadas às equipes assistenciais e de gestão, e maior integração da assistência farmacêutica com a rede de atenção.

Abstract This study evaluated the adherence of physicians to the Clinical Protocol and Therapeutic Guidelines on Parkinson's Disease (CPTG-PD) within the scope of the Unified Health System (SUS). A descriptive analysis of 375 drug application documents sent to the Pharmaceutical Services of the Rio Grande do Sul State Public Health Department (AF/SES/RS) between March and September 2016, and a structured survey to evaluate the physician's perception about the protocol and barriers to its use was conducted. Only 5.33% of the requests analyzed presented all the necessary data, considering the criteria of the protocol. The requests from specialists had a higher percentage of adherence to the diagnostic and dose criteria (p<0.05). The main barriers to protocol use were the lack of awareness or familiarity with the protocol (48%) and the lack of time to complete the mandatory documents (52%). More recently qualified physicians tended to perceive fewer barriers to protocol use (p<0.05). The results indicate that actions are still necessary to implement the PCDT-DP in medical practice, focusing on care and management teams. Greater integration between pharmaceutical assistance and the healthcare network is needed.

Extreme late chronotypes and social jetlag challenged by Antarctic conditions in a population of university students from Uruguay.

In humans, a person's chronotype depends on environmental cues and on individual characteristics, with late chronotypes prevailing in youth. Social jetlag (SJL), the misalignment between an individual׳s biological clock and social time, is higher in late chronotypes. Strong SJL is expected in Uruguayan university students with morning class schedules and very late entertainment activities. Sleep disorders have been reported in Antarctic inhabitants, that might be a response to the extreme environment or to the strictness of Antarctic life. We evaluated, for the first time in Uruguay, the chronotypes and SJL of 17 undergraduate students of the First Uruguayan Summer School on Antarctic Research, using Munich Chronotype Questionnaire (MCTQ) and sleep logs (SL) recorded during 3 phases: pre-Antarctic, Antarctic, and post-Antarctic. The midsleep point of free days corrected for sleep debt on work days (MSFsc,) was used as proxy of individuals' chronotype, whose values (around 6 a.m.) are the latest ever reported. We found a SJL of around 2 h in average, which correlated positively with MSFsc, confirming that late chronotypes generate a higher sleep debt during weekdays. Midsleep point and sleep duration significantly decreased between pre-Antarctic and Antarctic phases, and sleep duration rebounded to significant higher values in the post-Antarctic phase. Waking time, but not sleep onset time, significantly varied among phases. This evidence suggests that sleep schedules more likely depended on the social agenda than on the environmental light-dark shifts. High motivation of students towards Antarctic activities likely induced a subjective perception of welfare non-dependent on sleep duration.

The influence of school time on sleep patterns of children and adolescents.

OBJECTIVE: This epidemiological study evaluated the impact of school time on sleep parameters of children and adolescents. METHODS: This cross-sectional study involved 639 elementary and high school students (mean age 13.03 years, range 8-18, 58.5% female) from the south of Brazil. Participants answered the Morningness-Eveningness Questionnaire (MEQ), and were asked about their sleeping habits on weekdays and weekends. Sleep deficit was defined as the difference between sleep duration on weekdays and weekends. RESULTS: The morning-school-time students presented significantly higher age, bedtime and wake up differences, sleep deficits, and social jetlag. The sleep deficit presented by girls was greater than that observed in boys of the same age. The difference between weekday and weekend waking times was also significantly greater in girls than in boys aged 13-18 years. Sleep deficit was significantly positively correlated with age and differences in wake up times, and significantly negatively correlated with MEQ scores, social jetlag, difference between weekday and weekend bedtimes, midpoint of sleep on weekends, and midpoint of sleep on weekends corrected for sleep deficit. A step-by-step multivariate logistic regression identified social jetlag, the difference between waking times on weekdays and weekends, and the midpoint of sleep on weekends as significant predictors of sleep deficit (Adjusted R(2) = 0.95; F = 1606.87; p <0.001). CONCLUSION: The results showed that school time influences the sleep parameters. The association of school schedules and physiological factors influence the sleep/wake cycle.

Ancestral sleep.

While we do not yet understand all the functions of sleep, its critical role for normal physiology and behaviour is evident. Its amount and temporal pattern depend on species and condition. Humans sleep about a third of the day with the longest, consolidated episode during the night. The change in lifestyle from hunter-gatherers via agricultural communities to densely populated industrialized centres has certainly affected sleep, and a major concern in the medical community is the impact of insufficient sleep on health [1,2]. One of the causal mechanisms leading to insufficient sleep is altered exposure to the natural light-dark cycle. This includes the wide availability of electric light, attenuated exposure to daylight within buildings, and evening use of light-emitting devices, all of which decrease the strength of natural light-dark signals that entrain circadian systems [3].

Differential susceptibility of BALB/c, C57BL/6N, and CF1 mice to photoperiod changes.

OBJECTIVE: Circadian disturbances common to modern lifestyles have been associated with mood disorders. Animal models that mimic such rhythm disturbances are useful in translational research to explore factors contributing to depressive disorders. This study aimed to verify the susceptibility of BALB/c, C57BL/6N, and CF1 mice to photoperiod changes. METHODS: Thermochron iButtons implanted in the mouse abdomen were used to characterize temperature rhythms. Mice were maintained under a 12:12 h light-dark (LD) cycle for 15 days, followed by a 10:10 h LD cycle for 10 days. Cosinor analysis, Rayleigh z test, periodograms, and Fourier analysis were used to analyze rhythm parameters. Paired Student's t test was used to compare temperature amplitude, period, and power of the first harmonic between normal and shortened cycles. RESULTS: The shortened LD cycle significantly changed temperature acrophases and rhythm amplitude in all mouse strains, but only BALB/c showed altered period. CONCLUSION: These findings suggest that BALB/c, the preferred strain for stress-induced models of depression, should also be favored for exploring the relationship between circadian rhythms and mood. Temperature rhythm proved to be a useful parameter for characterizing rhythm disruption in mice. Although disruption of temperature rhythm has been successfully documented in untethered mice, an evaluation of desynchronization of other rhythms is warranted.

Effects of N-acetylcysteine and imipramine in a model of acute rhythm disruption in BALB/c mice.

Circadian rhythm disturbances are among the risk factors for depression, but specific animal models are lacking. This study aimed to characterize the effects of acute rhythm disruption in mice and investigate the effects of imipramine and N-acetylcysteine (NAC) on rhythm disruption-induced changes. Mice were exposed to 12:12-hour followed by 10:10-hour light:dark cycles (LD); under the latter, mice were treated with saline, imipramine or NAC. Rhythms of rest/activity and temperature were assessed with actigraphs and iButtons, respectively. Hole-board and social preference tests were performed at the beginning of the experiment and again at the 8th 10:10 LD, when plasma corticosterone and IL-6 levels were also assessed. Actograms showed that the 10:10 LD schedule prevents the entrainment of temperature and activity rhythms for at least 13 cycles. Subsequent light regimen change activity and temperature amplitudes showed similar patterns of decline followed by recovery attempts. During the 10:10 LD schedule, activity and temperature amplitudes were significantly decreased (paired t test), an effect exacerbated by imipramine (ANOVA/SNK). The 10:10 LD schedule increased anxiety (paired t test), an effect prevented by NAC (30 mg/kg). This study identified mild but significant behavioral changes at specific time points after light regimen change. We suggest that if repeated overtime, these subtle changes may contribute to lasting behavioral disturbancess relevant to anxiety and mood disorders. Data suggest that imipramine may contribute to sustained rhythm disturbances, while NAC appears to prevent rhythm disruption-induced anxiety. Associations between sleep/circadian disturbances and the recurrence of depressive episodes underscore the relevance of potential drug-induced maintenance of disturbed rhythms.

Differences in circadian patterns between rural and urban populations: an epidemiological study in countryside.

The physiological pattern of the sleep-wake cycle is influenced by external synchronizing agents such as light and social patterns, creating variations in each individual's preferred active and sleep periods. Because of the demands of a 24-h working society, it may be imperative for many people to adapt their sleep patterns (physiologically) to their daily activities. Therefore, we analyzed the difference in sleep patterns and chronobiological parameters between an essentially rural farming and urban small-town populations. We studied 5942 subjects (women, 67.1%, N = 3985; mean age, 44.3 ± 13.1 years), from which the chronotype, circadian sleep pattern, and period of light exposure were collected using the Munich Chronotype Questionnaire (MCTQ). A structured questionnaire was also made for collection of social and demographic information. Compared with the urban population (N = 3427, 57.7%), the rural population (N = 2515, 42.3%) presented a more predominantly early sleep pattern, as determined by the mid-sleep phase (rural: 2.26 ± 1.16; urban: 3.15 ± 1.55; t-test, p < 0.001). We also found less social jetlag (rural: 0.32; urban: 0.55; Mann-Whitney U test, p < 0.001) and higher light-exposure (rural: 9.55 ± 2.31; urban: 8.46 ± 2.85; t test, p < 0.001) in the rural population. Additionally, the rural population presented a higher prevalence of psychiatric disorders (rural: 156, 6.20%; urban: 165, 4.80%; Chi-square, p < 0.05), and a lower prevalence of metabolic diseases (rural: 143, 5.70%; urban: 225, 6.60%; Chi-square, p < 0.05). The significant difference in sleep parameters, chronotype, and light exposure between groups remained after multivariate regression analysis (r(2 )= 0.41, F = 297.19, p < 0.001, ß = 1.208). In this study, there was a significant difference between the rural and urban populations in natural light exposure and sleeping patterns. Because of agricultural work schedules, rural populations spend considerable time outside that is an obligation related to work schedules. Our results emphasize the idea that latitude may not be the main factor influencing individual circadian habits. Rather, circadian physiology adapts to differences in exposure to light (natural and artificial) as well as social and work schedules.

Circadian rhythm of energy expenditure and oxygen consumption.

BACKGROUND: This study aimed to evaluate the effect of continuous and intermittent methods of enteral nutrition (EN) administration on circadian rhythm. MATERIALS AND METHODS: Thirty-four individuals, aged between 52 and 80 years, were fed through a nasoenteric tube. Fifteen individuals received a continuous infusion for 24 hours/d, and 19 received an intermittent infusion in comparable quantities, every 4 hours from 8:00 to 20:00. In each patient, 4 indirect calorimetric measurements were carried out over 24 hours (A: 7:30, B: 10:30, C: 14:30, and D: 21:30) for 3 days. RESULTS: Energy expenditure and oxygen consumption were significantly higher in the intermittent group than in the continuous group (1782 ± 862 vs 1478 ± 817 kcal/24 hours, P = .05; 257 125 vs 212 117 ml/min, P = .048, respectively). The intermittent group had higher levels of energy expenditure and oxygen consumption at all the measured time points compared with the continuous group. energy expenditure and oxygen consumption in both groups were significantly different throughout the day for 3 days. CONCLUSION: There is circadian rhythm variation of energy expenditure and oxygen consumption with continuous and intermittent infusion for EN. This suggests that only one indirect daily calorimetric measurement is not able to show the patient's true needs. Energy expenditure is higher at night with both food administration methods. Moreover, energy expenditure and oxygen consumption are higher with the intermittent administration method at all times.

Chronotype: a review of the advances, limits and applicability of the main instruments used in the literature to assess human phenotype.

The study of circadian typology differences has increased in the last few years. As a result, new instruments have been developed to estimate the individual circadian phase of temporal human behavior, also referred as chronotype. The current review was conducted to evaluate the differences among the questionnaires most frequently used to assess chronotype: the Morningness-Eveningness Questionnaire (MEQ), the Composite Scale of Morningness (CSM), and the Munich Chronotype Questionnaire (MCTQ). Each instrument evaluates a different aspect of chronotype. MEQ is considered to evaluate the phase preferences of individual behavior over a 24-hour day, while MCTQ measures the phase of sleep positions for both free and work days. CSM is similar to MEQ, but is more sensitive to measure shift work. The concept of chronotype has been used to refer to phase positions or phase preferences in the literature reviewed. Most of the time this is a consequence of different interpretations: it is not clear whether phase preferences are a direct manifestation of the individual's internal clock or a result of external cues, e.g., social interaction (including the alarm clock). Also, phase preferences are not uniform throughout life. Therefore, a single assessment, not taking age into consideration, will not accurately describe the sample. We suggest that MCTQ is the best instrument for investigators dealing with desynchronization and as an instrument for sleep phase. Conversely, if the goal is to assess characteristics that change under specific situations - chronotype -, the MEQ should be used.