1,721,074 research outputs found
Individual differences in light sensitivity affect sleep and circadian rhythms
No full textArtificial lighting is omnipresent in contemporary society with disruptive consequences for human sleep and circadian rhythms because of overexposure to light, particularly in the evening/night hours. Recent evidence shows large individual variations in circadian photosensitivity, such as melatonin suppression, due to artificial light exposure. Despite the emerging body of research indicating that the effects of light on sleep and circadian rhythms vary dramatically across individuals, recommendations for appropriate light exposure in real-life settings rarely consider such individual effects. This review addresses recently identified links among individual traits, for example, age, sex, chronotype, genetic haplotypes, and the effects of evening/night light on sleep and circadian hallmarks, based on human laboratory and field studies. Target biological mechanisms for individual differences in light sensitivity include differences occurring within the retina and downstream, such as the central circadian clock. This review also highlights that there are wide gaps of uncertainty, despite the growing awareness that individual differences shape the effects of evening/night light on sleep and circadian physiology. These include (1) why do certain individual traits differentially affect the influence of light on sleep and circadian rhythms; (2) what is the translational value of individual differences in light sensitivity in populations typically exposed to light at night, such as night shift workers; and (3) what is the magnitude of individual differences in light sensitivity in population-based studies? Collectively, the current findings provide strong support for considering individual differences when defining optimal lighting specifications, thus allowing for personalized lighting solutions that promote quality of life and health
Exploring scoring methods for research studies: Accuracy and variability of visual and automated sleep scoring.
No full textSleep studies face new challenges in terms of data, objectives and metrics. This requires reappraising the adequacy of existing analysis methods, including scoring methods. Visual and automatic sleep scoring of healthy individuals were compared in terms of reliability (i.e., accuracy and stability) to find a scoring method capable of giving access to the actual data variability without adding exogenous variability. A first dataset (DS1, four recordings) scored by six experts plus an autoscoring algorithm was used to characterize inter-scoring variability. A second dataset (DS2, 88 recordings) scored a few weeks later was used to explore intra-expert variability. Percentage agreements and Conger's kappa were derived from epoch-by-epoch comparisons on pairwise and consensus scorings. On DS1 the number of epochs of agreement decreased when the number of experts increased, ranging from 86% (pairwise) to 69% (all experts). Adding autoscoring to visual scorings changed the kappa value from 0.81 to 0.79. Agreement between expert consensus and autoscoring was 93%. On DS2 the hypothesis of intra-expert variability was supported by a systematic decrease in kappa scores between autoscoring used as reference and each single expert between datasets (.75-.70). Although visual scoring induces inter- and intra-expert variability, autoscoring methods can cope with intra-scorer variability, making them a sensible option to reduce exogenous variability and give access to the endogenous variability in the data
Circadian misalignment: A biological basis for mood vulnerability in shift work
No full textBackgroundApproximately one in five workers perform night shift work. Epidemiological studies suggest that night shift workers are at a 25–30% higher risk for mental illnesses, including depression and anxiety, which is an increasingly important socioeconomic burden for the workforce. Thus, it is important to determine how shift work negatively affects mood, as it will help identify mechanisms that underlie a night shift worker's higher risk for developing mood disturbances.MethodsThis opinion discusses recently identified, potential biological mechanisms—including the role of the circadian system and circadian misalignment—underlying mood vulnerability in shift workers. Studies included are recent epidemiological, human laboratory studies and animal preclinical work on night shift work or circadian misalignment. Target biological mechanisms of interest discussed here include circadian misalignment effects on brain activity and brain–gut axis, essential for mood regulation.ResultsCircadian misalignment, which corresponds to the misalignment between biological (circadian) system and daily sleep-wake behaviours, can adversely affect mood levels and cortical activity underlying mood regulation. Furthermore, animal preclinical work shows that the brain–gut axis function is not only implicated in mood regulation but can disrupt specific metabolites essential for mood regulation when animals are exposed to circadian disruption.ConclusionsCircadian misalignment is a key mechanism underlying mood in e.g. shift workers. Therefore, understanding its role and applying sleep/circadian behavioural interventions to mitigate the adverse consequences of circadian misalignment on mood have the potential to improve quality of life, which is tightly associated with mood and sleep quality, in shift workers
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