Efetividade da suplementação de melatonina segundo as revisões sistemáticas Cochrane / Effectiveness of melatonin supplementation according to Cochrane systematic reviews

Contextualização: A melatonina é um hormônio endógeno encontrado em quase todos os organismos e participa de vários processos fisiológicos. A suplementação de melatonina tem sido preconizada na mídia para o tratamento e prevenção de várias doenças. Entretanto, há carência de informações científicas disponíveis sobre seu real benefício para a saúde. Objetivos: Sumarizar as evidências de revisões sistemáticas da Cochrane, referentes à efetividade das intervenções com suplementação de melatonina em humanos. Métodos: Trata-se de overview de revisões sistemáticas Cochrane. Procedeu-se à busca na Cochrane Library (2023), sendo utilizado o descritor "MELATONIN". Todas as revisões sistemáticas de ensaios clínicos foram incluídas. O desfecho primário de análise foi a melhora clínica, a redução dos sintomas ou a prevenção da doença. Resultados: Oito estudos foram incluídos, totalizando 53 ensaios clínicos e 4.024 participantes. Houve evidência de efetividade apenas para controle de ansiedade em pacientes em pré-operatório (evidência moderada) em comparação com placebo e para prevenção e tratamento de jet lag de fuso horário (evidência alta de certeza). Discussão: Embora seja muito veiculada na mídia, a suplementação de melatonina carece de estudos de qualidade para análise de sua efetividade. Os estudos clínicos disponíveis até o momento são heterogêneos e apresentam limitações metodológicas. Poucas análises convergem com segurança para um bom nível de evidência que permita sua recomendação. Conclusão: Não há suporte com bom nível de evidência atualmente para a maioria das intervenções com suplementação de melatonina, sendo recomendada a realização de novos estudos prospectivos para melhor robustez dos achados e análises.

Trastornos circadianos del sueño / Circadian Sleep Disorders

Resumen El sistema circadiano está sincronizado al ciclo luz-oscuridad que es generado por la rotación de la tierra, asegurando que la vigilia sea durante el día y que el sueño ocurra durante la noche. Sin embargo, el ritmo de sueño-vigilia puede estar desincronizado del ciclo luz-oscuridad o desincronizado de manera endógena, dando como resultado: insomnio, fatiga y bajo rendimiento en las actividades cotidianas. Mientras que los trastornos del sueño están clasificados por la Asociación Americana de Trastornos del Sueño como: disomnias intrínsecas, disomnias extrínsecas, parasomnias o trastornos del sueño médicos/psiquiátricos. Los trastornos circadianos del sueño se han categorizado por separado, en parte para reconocer que en la mayoría de los casos la etiología de los trastornos circadianos es una mezcla de factores internos y ambientales, o por un desajuste temporal entre ambos. Los síntomas generalmente son insomnio o hipersomnia, síntomas comunes en pacientes con trastornos circadianos del sueño, aunque hay otras causas a las que pueden atribuirse y que deben excluirse antes de realizar el diagnóstico de un trastorno circadiano del sueño. En el paciente sin otra patología del sueño, un registro diario de actividades, comidas, ejercicio, siestas y la hora de acostarse es una herramienta esencial para evaluar los trastornos circadianos del sueño. Estos registros deben mantenerse durante 2 semanas o más, ya que una perturbación debida a cambios de trabajo o viajes a través de zonas horarias puede tener efectos sobre el sueño y el estado de alerta durante el día, semanas después del evento.

Abstract The circadian system is synchronized to the light-dark cycle generated by the rotation of the earth, ensuring that wakefulness is during the day and sleep occurs at night. However, the sleep-wake rhythm may be out of sync with the light-dark cycle or endogenously out of sync, resulting in insomnia, fatigue, and poor performance in activities of daily living. Sleep disorders are classified by the American Sleep Disorders Association, as intrinsic dyssomnias, extrinsic dyssomnias, parasomnias, or medical/psychiatric sleep disorders. Circadian sleep disorders have been categorized separately to recognize that in most cases the etiology of circadian disturbances is a mix of internal and environmental factors or a temporary mismatch between the two. Symptoms are usually insomnia or hypersomnia, common symptoms in patients with circadian sleep disorders although other causes can be attributed and must be excluded before a diagnosis of a circadian sleep disorder is made. In the patient without other sleep pathology, a daily record of activities, meals, exercise, naps, and bedtime is an essential tool in assessing circadian sleep disorders. These records should be kept for 2 weeks or more, as a disturbance due to job changes or travel across time zones can have effects on sleep and daytime alertness weeks after the event.

SNORE (Sleep Deprivation Among Night Shift Health Staff on Rotation Evaluation) Study Protocol

Background: SNORE (Sleep deprivation among Night shift health staff On Rotation-Evaluation) study is conceptualized to study the effects of sleep deprivation on healthcare professionals working night shifts on rotation. Materials and Methods: A comparative cross-sectional study is devised including health-care profes-sionals working night shifts on rotation at a tertiary level health-care facility, using a semi-structured questionnaire which can test sleep deprivation, cognitive ability, and quality of life. The process is to ap-proach 309 probable study participants based on stratified random sampling, after exclusion of health-care professionals with other factors which may interfere with sleep deprivation testing. Discussion: The study protocol was set in such a way as to randomly include participants from all cadres of healthcare providers as per population proportion. By measuring the effects on cognitive effect and quality of life necessary steps can be taken to provide better quality of life and to decrease cognitive im-pairment, especially among health care professionals working night shifts.

Síndrome de jet lag o cambio de zonas de tiempo / The jet lag syndrome or time-zone changes

Resumen Nuestro planeta, así como la vida que en él se desarrolla, se encuentra en constante movimiento. Los ritmos geofísicos influyen en la actividad de los organismos, de tal manera que los seres vivos han desarrollado mecanismos adaptativos para poder responder a las variaciones diarias del medio ambiente. El sistema circadiano es el responsable de responder a estas variaciones cíclicas ambientales. Cuando se modifican las señales ambientales, como en un viaje que implica atravesar varias zonas horarias, se ocasionan cambios fisiológicos que han llevado a buscar estrategias para contrarrestar los síntomas que se presentan; estas estrategias incluyen el ejercicio programado, la exposición a la luz brillante, la melatonina y la alimentación programada.

Abstract Our planet and the life that develops in it are in constant movement, therefore, the geophysical rhythms influence the activity of organisms, in such a way that living beings have developed adaptative mechanims in order to respond to the daily variations of the environment. The circadian system is responsible for responding to these cyclical environmental variations. When the environmental signals are modified, like for instance, on a trip that involves crossing several time zones, physiological changes occur. This results in searching for possible strategies to counteract the symptomatology. These strategies include scheduled exercise, exposure to a bright light, melatonin and scheduled meals.

De la cronobiología a la cronomedicina / From chronobiology to chronomedicine

Resumen Los grandes avances científicos en diversas áreas biomédicas, así como sus demandas de conocimiento y dedicación, han alejado al investigador de la cama del paciente y, por su parte, el clínico poco a poco se trasforma en un técnico en atención médica, y deja de lado el conocimiento científico. Es así como nace la necesidad de unir la investigación básica y la clínica, es decir, trasladar los hallazgos del laboratorio a la medicina clínica. La medicina traslacional surge para darle continuidad a la medicina basada en evidencias, obtenidas en los laboratorios. Sin embargo, la investigación biomédica básica no se limita a la metabolómica, la proteómica, la terapia génica o a la nanotecnología, por mencionar algunas líneas de investigación; existen otras mucho más sencillas, pero no por esto menos importantes. El estudio de los ritmos biológicos es un claro ejemplo donde se ha logrado establecer el puente de transmisión y aplicación de la ciencia básica a la aplicación a problemas de salud. La cronomedicina propone un mejor entendimiento y manipulación de la fisiología, utilizando sus variaciones circadianas como parte del diagnóstico y tratamiento de algunas patologías.

Abstract The major scientific advances in various biomedical areas as well as its demands for knowledge and dedication have moved away the researcher from of the patient's bedside, and the clinician is gradually been transformed into a technician in medical care, leaving aside the scientific knowledge. Therefore the need to join the basic research and the clinic arose and to translate the findings of the laboratory to clinical medicine was born. The translational medicine appeared to give continuity to the evidence-based medicine obtained in the laboratory. However the basic biomedical research is not limited to metabolomics, proteomics, gene therapy or nanotechnology, just to mention a few research lines, some of these are much easier but are not less important. The study of biological rhythms is a clear example of successfully setting up the bridge between transmission and the application of basic science applied to health problems. The chronomedicine proposes a better understanding and manipulation of the physiology, using circadian variations as part of the diagnosis and treatment of certain pathologies.

Gender Differences in the Relationship between Social Jet Lag, Depression, and Obesity in Korean Children and Adolescents

OBJECTIVES: A majority of South Korean adolescents experience chronic sleep-deprivation due to social jet lag. In this study, we investigated gender differences in the relationship between social jet lag, depression, and obesity in Korean children and adolescents. METHODS: Our sample consisted of 4,380 adolescents (elementary school cohort n=2,141, middle school cohort n=2,239) who participated in the Korean Children and Youth Panel Survey. In order to analyze the gender differences in the relationship between sleep time difference, obesity and depression, t-test and chi-square test were utilized. RESULTS: Both cohorts revealed that the difference in weekday/weekend sleep duration (2.19+/-1.42 vs. 1.68+/-1.36, p2 hours). Both elementary school [chi2 (1)=8.73, p<0.05] and middle school cohorts [chi2 (1)=61.29, p<0.001] showed significant gender differences. CONCLUSIONS: There were especially more girls who reported a discrepancy of 2 or more hours of weekday/weekend sleep duration. In summary, intervention for social jet lag may be important to consider in adolescents.

Sleep and Resilience / 수면정신생리

Good sleepers tend to more resilient than poor sleepers. As sleep and resilience may have a bidirectional relationship, it is important to explore the relationship between healthy sleep and resilience. Objectively and subjectively measured sleep quality showed positive association with resiliency. In one study, more resilient adolescents had higher sleep efficiency, less light sleep, more slow-wave sleep, and a smaller number of awakenings after sleep onset. Circadian typology, jetlag and circadian misalignment may be associated with the capacity to deal with adversity. Eveningness, exposure to chronic jetlag and circadian misalignment might be risk factors for development of psychological problems and mental disorders. Additional studies are needed to evaluate whether promoting healthy sleep behaviors results in increased resilience.

Slow and fast orthodromic and antidromic variants in acute 9-h jet-lagged pygmy field mice.

Biological clocks help organism to adapt temporally to a variety of rhythmic environmental cues. Acute changes in the rhythmicity of entraining cues causes short- to long-term physiological distress in individuals, for example, those occurring during jet-lag after long-haul transmeridial flights, or shift work. Variations in the rate of re-entrainment to a 9 h advanced schedule (simulation of acute Jet-lag/shift work) in the Indian pygmy field mouse, Mus terricolor are reported. Wheel- and lab-acclimated adult male mice were entrained to a 12:12 h light:dark (LD) cycles, followed by a 9 h advance in the LD cycle. In response, these mice either advanced or delayed their activity onsets, with individual variation in the rate and direction. Rapid orthodromic (advancing) re-entrainers exhibited a coincidence of activity onsets with the new dark onset in <=3 days, while gradually advancing re-entrainers took ~9 days or more. Delayers (antidromic) also either re-entrained very rapidly (<=2 days), or gradually (~9 days). Acrophase measurement confirmed the direction of the transients, which did not depend on the free-running period. Such different patterns might determine the differential survival of individuals under the pressure of re-entrainment schedules seen in jet-lag and shift work.

Circadian rhythm sleep disorders.

Circadian rhythm sleep disorders are common conditions manifested as misalignment between the sleep period and the physical/social 24-h environmental cycle. Delayed sleep phase (typical in adolescents) and advanced sleep phase (frequent in the elderly), situations in which the sleep period is displaced to a later or earlier time, respectively, are the two most prevalent circadian rhythm sleep disorders. There are, however, nine possible diagnoses of clinical interest. Since light is the main cue used in synchronizing the biological clock, blind individuals and night-shift/rotating-shift workers are more prone to develop circadian rhythm sleep disorders. In this article, the circadian rhythm syndromes included in the new International Classification of Sleep Disorders are reviewed as well as the most recent guidelines for diagnosis and treatment.

A Study on the Physical Environment in the Cockpit of Air-transportation Airplane

BACKGROUND: The physical environment (noise, temperature & humidity, microwaves, and jet lag) in the cockpit of air-transportation airplane is well known to have adverse effects on flight crew. But due to airplane security reasons and so on, the true environment could not be fully assessed up to now. The object of this study was to measure the status, to examine the effects of the environment, and to suggest the protection from them. METHODS: The status except jet lag was measured from the first officer seat in the B747-400/ B737-400/500 cockpit at several flight stage (pre-flight, after engine start, take off, climb, cruise, descent). Jet lag was examined through a flight crew schedule for 45 days. RESULTS: Noise level (74-84 dB), humidity (19%), microwaves(well above the caution and dangerous range), and jet lag (not enough to adjust from flight) were measured. The physical environment was examined which had considerable adverse effects on flight crew. CONCLUSION: The flight crew should be aware of the status which increase work load and physical load during flight. They must leave the cockpit as much as possible while they are off duty and be isolated from such status during rest.

Jet Lag and Circadian Rhythms / 수면정신생리

As jet lag of modern travel continues to spread, there has been an exponential growth in popular explanations of jet lag and recommendations for curing it. Some of this attention are misdirected, and many of those suggested solutions are misinformed. The author reviewed the basic science of jet lag and its practical outcome. The jet lag symptoms stemed from several factors, including high-altitude flying, lag effect, and sleep loss before departure and on the aircraft, especially during night flight. Jet lag has three major components; including external desynchronization, internal desynchronization, and sleep loss. Although external desynchronization is the major culprit, it is not at all uncommon for travelers to experience difficulty falling asleep of remaining asleep because of gastrointestinal distress, uncooperative bladders, or nagging headaches, Such unwanted intrusions most likely to reflect the general influence of internal desynchronization. From the free-running subjects, the data has revealed that sleep tendency, sleepiness, the spontaneous duration of sleep, and REM sleep propensity, each varied markedly with the endogenous circadian phase of the temperature cycle, despite the facts that the average period of the sleep-wake cycle is different from that of the temperature cycle under these conditions. However, whereas the first ocurrence of slow wave sleep is usually associated with a fall in temperature, the amount of SWS is determined primarily by the length of prior wakefulness and not by circadian phase. Another factor to be considered for flight in either direction is the amount of prior sleep loss or time awake. An increase in sleep loss or time awake would be expected to reduce initial sleep latency and enhance the amount of SWS. By combining what we now know about the circadian characteristics of sleep and homeostatic process, many of the diverse findings about sleep after transmeridian flight can be explained. The severity of jet lag is directly related to two major variables that determine the reaction of the circadian system to any transmeridian flight, eg., the direction of flight, and the number of time zones crossed. Remaining factor is individual differences in resynchrnization. After a long flight, the circadian timing system and homeostatic process can combine with each other to produce a considerable reduction in well-being. The author suggested that by being exposed to local zeit-gebers and by being awake sufficient to get sleep until the night, sleep improves rapidly with resynchronization following time zone change.