Sleep, ageing and night work

Studies have shown that the frequency or worsening of sleep disorders tends to increase with age and that the ability to perform circadian adjustments tends to decrease in individuals who work the night shift. This condition can cause consequences such as excessive sleepiness, which are often a factor in accidents that occur at work. The present study investigated the effects of age on the daytime and nighttime sleep patterns using polysomnography (PSG) of long-haul bus drivers working fixed night or day shifts. A total of 124 drivers, free of sleep disorders and grouped according to age (<45 years, N = 85, and ≥45 years, N = 39) and PSG timing (daytime (D) PSG, N = 60; nighttime (N) PSG, N = 64) participated in the study. We observed a significant effect of bedtime (D vs N) and found that the length of daytime sleep was shorter [D: <45 years (336.10 ± 73.75 min) vs N: <45 years (398 ± 78.79 min) and D: ≥45 years (346.57 ± 43.17 min) vs N: ≥45 years (386.44 ± 52.92 min); P ≤ 0.05]. Daytime sleep was less efficient compared to nighttime sleep [D: <45 years (78.86 ± 13.30 percent) vs N: <45 years (86.45 ± 9.77 percent) and D: ≥45 years (79.89 ± 9.45 percent) and N: ≥45 years (83.13 ± 9.13 percent); P ≤ 0.05]. An effect of age was observed for rapid eye movement sleep [D: <45 years (18.05 ± 6.12 percent) vs D: ≥45 years (15.48 ± 7.11 percent) and N: <45 years (23.88 ± 6.75 percent) vs N: ≥45 years (20.77 ± 5.64 percent); P ≤ 0.05], which was greater in younger drivers. These findings are inconsistent with the notion that older night workers are more adversely affected than younger night workers by the challenge of attempting to rest during the day.

Relationship between Brazilian airline pilot errors and time of day

Flight safety is one of the most important and frequently discussed issues in aviation. Recent accident inquiries have raised questions as to how the work of flight crews is organized and the extent to which these conditions may have been contributing factors to accidents. Fatigue is based on physiologic limitations, which are reflected in performance deficits. The purpose of the present study was to provide an analysis of the periods of the day in which pilots working for a commercial airline presented major errors. Errors made by 515 captains and 472 copilots were analyzed using data from flight operation quality assurance systems. To analyze the times of day (shifts) during which incidents occurred, we divided the light-dark cycle (24:00) in four periods: morning, afternoon, night, and early morning. The differences of risk during the day were reported as the ratio of morning to afternoon, morning to night and morning to early morning error rates. For the purposes of this research, level 3 events alone were taken into account, since these were the most serious in which company operational limits were exceeded or when established procedures were not followed. According to airline flight schedules, 35 percent of flights take place in the morning period, 32 percent in the afternoon, 26 percent at night, and 7 percent in the early morning. Data showed that the risk of errors increased by almost 50 percent in the early morning relative to the morning period (ratio of 1:1.46). For the period of the afternoon, the ratio was 1:1.04 and for the night a ratio of 1:1.05 was found. These results showed that the period of the early morning represented a greater risk of attention problems and fatigue.

Relationship between the quality of life and the severity of obstructive sleep apnea syndrome

The effects of sleep disorders on the quality of life (QOL) have been documented in the literature. Excessive sleepiness and altered circadian rhythms may negatively affect ability to learn, employment, and interpersonal relations, and directly degrade QOL. The objective of the present study was to evaluate the impact of obstructive sleep apnea syndrome of varying severity on QOL. The study was conducted on 1892 patients aged 18 years or older referred by a physician to the Sleep Institute, São Paulo, with complaints related to apnea (snoring, excessive daytime sleepiness, hyperarousal, and fatigue). They were submitted to overnight polysomnography for the diagnosis of sleep disorders from August 2005 through April 2006. The patients completed the Epworth Sleepiness Scale and QOL SF-36 sleep questionnaires. They were classified as non-physically active and physically active and not-sleepy and sleepy and the results of polysomnography were analyzed on the basis of the apnea hypopnea index (AHI). The apneic subjects showed a reduction in QOL which was proportional to severity. There was a significant decrease in all domains (physical functioning, role physical problems, bodily pain, general health perceptions, vitality, social functioning, emotional problems, general mental health) for apneics with AHI >30, who generally were sleepy and did not participate in physical activities (P < 0.05). The present study provides evidence that the impact of sleep disorders on QOL in apneics is not limited to excessive daytime sleepiness and that physical activity can contribute to reducing the symptoms. Thus, exercise should be considered as an adjunct interventional strategy in the management of obstructive sleep apnea syndrome.

Two pedigrees with restless legs syndrome in Brazil

Numerous studies have suggested a substantial genetic contribution in the etiology of the primary form of restless legs syndrome (RLS) and periodic leg movements (PLM). We describe the symptoms, the sleep profiles and physiological parameters of two families in which several members present RLS/PLM. The proband of family 1 is a 70-year-old woman and the proband of family 2 is a 57-year-old woman; both have exhibited the symptoms since the age of 20 years. All patients in both families were diagnosed with RLS according to the criteria of the International RLS Study Group. Polysomnographic recordings were performed to quantify and to describe PLM during sleep. Sleep parameters showed decreased sleep efficiency, increased sleep latency in the arousal index and the presence of PLM in all subjects. One of the families showed an exact profile of dominant inheritance with anticipation of age at onset. In the other family, the founders were blood relatives and there was no affected member in the third generation suggesting a recessive mode of inheritance. RLS/PLM is a prevalent sleep disorder affecting about 5 to 15 percent of the population and one that substantially impairs healthy sleep patterns. Efforts to understand the underlying pathophysiology will contribute to improve the sleep and life quality of these patients.

Estudo dos efeitos de ambiente sobre as características lineares de tipo em rebanhos bovinos da raça Holandesa / Study of environmental effects on linear type traits in Brazilian Holstein

Efeitos de estádio da lactação, idade à classificação e grupo contemporâneo de rebanho, ano e estação de classificação foram considerados nas análises de 21 características lineares de tipo e pontuação final de 2.122 animais da raça Holandesa, filhos de 178 reprodutores e nascidos em 83 rebanhos. Utilizou-se o método dos quadrados mínimos nas análises de variância das características. O efeito de estádio da lactação teve influência sobre as características do sistema mamário, evidenciando que houve alterações morfológicas durante o período de lactação para todas as características de úbere, exceto inserção do úbere anterior, textura do úbere e comprimento dos tetos. Dentre as características de conformação/capacidade corporal, profundidade corporal foi a mais influenciada pelo estádio da lactação, seguida do tamanho corporal, largura torácica e força lombar. Para todas as características de conformação/capacidade corporal o efeito da idade à classificação revelou-se altamente significativo. Dentre as características lineares da categoria pernas/pés, a variável idade à classificação foi importante (P<0,05) apenas para vista lateral das pernas. O efeito de idade sobre as características de garupa variou consideravelmente, sendo importante apenas para largura (P<0,01). Pontuação final e angulosidade também foram influenciadas (P<0,01) pelo efeito da idade. A verificação de significância estatística indicou a existência de componentes de meio e evidenciou a importância do estudo desses componentes.

Correlações genéticas e fenotípicas entre características de tipo e produção de leite em bovinos da raça Holandesa / Genetic and phenotypic correlations between type traits and milk production in Holstein cattle

Correlações genéticas e fenotípicas entre 21 características lineares de tipo e produção de leite em até 305 dias de lactação foram estimadas pela máxima verossimilhança restrita sob modelo animal, a partir de dados da Associação de Criadores de Gado Holandês de Minas Gerais. Nas análises das características lineares, os efeitos fixos utilizados no modelo incluíram estádio da lactação, idade do animal, grupo contemporâneo de rebanho, ano e estação de classificação, e o efeito aleatório do pai da vaca. As características lineares que apresentaram maiores correlações genéticas com produção de leite foram largura do úbere posterior (0,60) e largura de garupa (0,37), indicando não haver antagonismo genético entre a seleção para essas características e a produção de leite. As correlações fenotípicas entre características lineares de tipo e produção de leite foram, em geral, menores do que as correlações genéticas correspondentes. As correlações fenotípicas entre as características lineares apresentaram-se altas dentro das seções de conformação/capacidade e de sistema mamário. Correlações genéticas entre algumas características lineares foram altas, possibilitando a exclusão de algumas delas do programa de classificação linear adotado para a raça Holandesa no Brasil.