Dauernachtarbeit: Eine Sichtung des vorhandenen Wissenstandes mit Thesen, Empfehlungen & Forschungsfragen

Im Falle der Dauernachtarbeit, also einer dauerhaften Schichtarbeit bei Nacht, ste-hen begründete Befürchtungen erheblicher Nachteile anderen Sichtweisen gegen-über. Dieser Artikel beruht auf einer umfassenden Literatursuche und einer breiten Diskussion in der Arbeitszeitgesellschaft. Es werden von Expertinnen und Experten konsensual abgestimmte Thesen zu der Wirkung von Dauernachtarbeit sowie zum Forschungsbedarf vorgestellt. Das Kernergebnis der Diskussion ist, dass Dauer-nachtarbeit in den meisten Fällen problematisch ist, aber auch Konstellationen exis-tieren, bei denen die Dauernachtarbeit wenig problematisch oder vielleicht sogar po-sitiv für manche Personen wirkt. Es besteht ein erheblicher Forschungsbedarf, um hier ein klares Bild zu gewinnen

Editorial: Vielfalt der Arbeitszeiten

Editorial zum Schwerpunktheft "Vielfalt der Arbeitszeiten

Social Connectedness on Facebook – An Explorative Study on Status Message Usage

With over 400 million active users Facebook is undeniably a large social phenomenon and one of the largest social networks on the Internet. Together with Facebook a variety of novel communication styles have developed, dramatically influencing social interaction. The underlying paper reports the results of a survey (N=109) analyzing Facebook’s micro-blogging function available through users’ status updates. Our results suggest that the use of status update messaging generates a feeling of connectedness between users. Furthermore, non-parametric analyses distinguishing between low- and highconnected groups have been performed and experimentally confirmed the existence of distinct user profiles as a function of the variable “feeling connected”. The analyses revealed that the more individuals use their status message function to actively reveal information about themselves, the more connected they feel. Connectedness seems the result of active information sharing modulated by the amount of information shared rather than by the type of information an individual is sharing

Short sleep duration and extremely delayed chronotypes in uruguayan youth: the role of school start times and social constraints

During adolescence, biological, psychosocial, and contextual factors converge in a “perfect storm” and have been put forward to explain the delay in chronotype observed at this age and the prevalence of disrupted sleep. This study provides evidence to support that chronotype and sleep patterns (particularly sleep duration) are socially constrained and to identify novel significant social predictors. Uruguayan public school activities are arranged in up to 4 shifts, creating a natural experiment to examine the effect of school timing on questionnaire-based assessments of sleep and chronotype. In this study, 268 high school students (15-18 years old) who attended school either on morning (0730 to 1130 h) or afternoon shifts (1130 h to 1530 h) responded to an adapted School Sleep Habits Survey. Students attending afternoon shifts had later chronotypes (a 1.5-h later midpoint of sleep on free days adjusted for sleep debt) than those attending the morning shift. Besides shift, evening social activities (including dinner time) were further identified as key predictors of late chronotypes, whereas age and gender were not. Sleep on school days was overall advanced and reduced with respect to weekends, and these effects were stronger in morning-shift students. Weekend sleep duration was similar between shifts, which probably caused the prevalence of reduced sleep durations (average weekly sleep duration, SDweek <8 h) to be higher in morning-shift students (almost 80%) than in afternoon-shift ones (34%). Reduced sleep duration was significantly higher in morning-shift students. In addition, age, chronotype, and dinner time became relevant determinants of sleep deficit only in the morning-shift students. Besides the important social constraint of early school start time, this is the first study to confirm the significance of other types of social pressures on both adolescents’ chronotype and sleep deficit, which can be useful as potential new targets for effective policies to protect adolescent sleep.ANII: POS_NAC_2015_1_1096

Arbeitszeitentwicklungen in Deutschland, Österreich und der Schweiz

Editorial des Schwerpunktheftes "Arbeitszeitentwicklungen in Deutschland, Österreich und der Schwei

Development of the circadian system in early life: maternal and environmental factors

In humans, an adaptable internal biological system generates circadian rhythms that maintain synchronicity of behavior and physiology with the changing demands of the 24-h environment. Development of the circadian system begins in utero and continues throughout the first few years of life. Maturation of the clock can be measured through sleep/wake patterns and hormone secretion. Circadian rhythms, by definition, can persist in the absence of environmental input; however, their ability to adjust to external time cues is vital for adaptation and entrainment to the environment. The significance of these external factors that influence the emergence of a stable circadian clock in the first years of life remain poorly understood. Infants raised in our post-modern world face adverse external circadian signals, such as artificial light and mistimed hormonal cues via breast milk, which may increase interference with the physiological mechanisms that promote circadian synchronization. This review describes the very early developmental stages of the clock and common circadian misalignment scenarios that make the developing circadian system more susceptible to conflicting time cues and temporal disorder between the maternal, fetal, infant, and peripheral clocks

Decreased psychomotor vigilance of female shift workers after working night shifts

We compared psychomotor vigilance in female shift workers of the Bergmannsheil University Hospital in Bochum, Germany (N = 74, 94% nurses) after day and night shifts. METHODS:Participants performed a 3-minute Psychomotor Vigilance Task (PVT) test bout at the end of two consecutive day and three consecutive night shifts, respectively. Psychomotor vigilance was analyzed with respect to mean reaction time, percentage of lapses and false starts, and throughput as an overall performance score, combining reaction time and error frequencies. We also determined the reaction time coefficient of variation (RTCV) to assess relative reaction time variability after day and night shifts. Further, we examined the influence of shift type (night vs. day) by mixed linear models with associated 95% confidence intervals (CI), adjusted for age, chronotype, study day, season, and the presence of obstructive sleep apnea (OSA). RESULTS:At the end of a night shift, reaction times were increased (&beta; = 7.64; 95% CI 0.94; 14.35) and the number of lapses higher compared to day shifts (exp(&beta;) = 1.55; 95% CI 1.16-2.08). By contrast, we did not observe differences in the number of false starts between day and night shifts. Throughput was reduced after night shifts (&beta; = -15.52; 95% CI -27.49; -3.46). Reaction times improved across consecutive day and night shifts, whereas the frequency of lapses decreased after the third night. RTCV remained unaffected by both, night shifts and consecutive shift blocks. DISCUSSION:Our results add to the growing body of literature demonstrating that night-shift work is associated with decreased psychomotor vigilance. As the analysis of RTCV suggests, performance deficits may selectively be driven by few slow reactions at the lower end of the reaction time distribution function. Comparing intra-individual PVT-performances over three consecutive night and two consecutive day shifts, we observed performance improvements after the third night shift. Although a training effect cannot be ruled out, this finding may suggest better adaptation to the night schedule if avoiding fast-changing shift schedules.</p

Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults

Ocular light exposure has important influences on human health and well-being through modulation of circadian rhythms and sleep, as well as neuroendocrine and cognitive functions. Prevailing patterns of light exposure do not optimally engage these actions for many individuals, but advances in our understanding of the underpinning mechanisms and emerging lighting technologies now present opportunities to adjust lighting to promote optimal physical and mental health and performance. A newly developed, international standard provides a SI-compliant way of quantifying the influence of light on the intrinsically photosensitive, melanopsin-expressing, retinal neurons that mediate these effects. The present report provides recommendations for lighting, based on an expert scientific consensus and expressed in an easily measured quantity (melanopic equivalent daylight illuminance (melaponic EDI)) defined within this standard. The recommendations are supported by detailed analysis of the sensitivity of human circadian, neuroendocrine, and alerting responses to ocular light and provide a straightforward framework to inform lighting design and practice

Data from "Circadian, Sleep and Caloric Intake Phenotyping in Type 2 Diabetes Patients with Rare Melatonin Receptor 2 Mutations and Controls: A Pilot Study"

Background: Melatonin modulates circadian rhythms in physiology and sleep initiation. Genetic variants of the MTNR1B locus, encoding the melatonin MT2 receptor, have been associated with increased type 2 diabetes (T2D) risk. Carriers of the common intronic MTNR1B rs10830963 T2D risk variant have modified sleep and circadian traits such as changes of the melatonin profile. However, it is currently unknown whether rare variants in the MT2 coding region are also associated with altered sleep and circadian phenotypes, including meal timing. Materials and Methods: In this pilot study, 28 individuals (50% male; 46-82 years old; 50% with rare MT2 mutations [T2D MT2]) wore actigraphy devices and filled out daily food logs for four weeks. We computed circadian, sleep, and caloric intake phenotypes, including sleep duration, timing, and regularity (assessed by the Sleep Regularity Index [SRI]), composite phase deviations (CPD) as a sleep timing-based proxy for circadian misalignment, and caloric intake patterns throughout the day. Using regression analyses, we estimated age- and sex-adjusted mean differences (MD) and 95% confidence intervals (95%CI) between the two patient groups. Secondary analyses also compare T2D MT2 to 15 healthy controls. Results: Patients with rare MT2 mutations had a later sleep onset (MD=1.23, 95%CI=0.42;2.04), and midsleep time (MD=0.91, 95%CI=0.12;1.70), slept more irregularly (MD in SRI=-8.98, 49 95%CI=-16.36;-1.60), had higher levels of behavioral circadian misalignment (MD in 50 CPD=1.21, 95%CI=0.51;1.92), were more variable in regards to duration between first caloric intake and average sleep offset (MD=1.08, 95%CI=0.07;2.08), and had more caloric episodes in a 24-hr day (MD=1.08, 95%CI=0.26;1.90), in comparison to T2D controls. Secondary analyses showed similar patterns between T2D MT2 and non-diabetic controls. Conclusion: This pilot study suggests that compared to diabetic and non-diabetic controls, T2D MT2 patients display a number of adverse sleep, circadian, and caloric intake phenotypes, including more irregular behavioral timing than T2D. A prospective study is needed to determine the role of these behavioral phenotypes in T2D onset and severity, especially in view of rare MT2 mutations.</p