The impact of chronotype on prosocial behavior

The association between chronotype and wages at mid-age

Sleep has been shown to affect economic outcomes, including wages. The mechanisms by which sleep affects wages remain unclear. We examine the relationship between chronotype - morning larks, evening owls - and wages at mid-age. We propose a novel model relating chronotype to wages in consideration of human, social, and health capital constructs. Empirically, we explore the effects of chronotype mediated through life course choices, such as work experience, trust, and health behaviour. The data come from the 46-year-old follow-up study of the Northern Finland Birth Cohort (1966) and from registers of the Finnish Tax Administration. We find evening chronotype to have a significant indirect negative effect on wages, which occurs through accumulating less work experience and through poor health outcomes. The effect is largest for male workers, with a total indirect effect on average wages of - 4%. We also provide evidence that chronotype has a long-term association with wages between 29 and 50 years of age. We conclude that evening-type workers are less suited to typical working hours and accumulate less human, social and health capital which in turn negatively affects their wages. Our findings are of great socio-economic importance because evening chronotypes make up a significant part of the population.

Environmental light exposure and mealtime regularity: Implications for human health

Light exposure and mealtime act as cues to the human circadian rhythm, which subsequently regulates various physiological functions in the body. However, modernization alters lifestyles, with changes to social and work-related activities independent of the natural light-dark cycle. This review summarizes the role of light exposure and regular mealtime on bodily processes and, ultimately, metabolic health. Various aspects of light are reviewed, including the type of light (natural/artificial), intensity (lux), spectral composition, time of exposure (night/day), and exposure duration. Further, the possible relationship between light exposure and mealtime irregularity is discussed as a function affecting metabolic health. In essence, research evidence suggests that mealtime regularity and light exposure habits based on the natural occurring light-dark cycle are essential for metabolic health in relation to an aligned circadian rhythm.

Pathways to adolescents' health: chronotype, bedtime, sleep quality and mental health

The strong relationship between sleep and health is defined in the literature. While the need for sleep increases in adolescence with the effect of physiological and hormonal changes, the studies have highlighted the serious sleeping problems of adolescents compared to childhood and adulthood. This study aimed to examine the relationship between chronotype, bedtime, sleep quality and mental health among adolescents. This research was a descriptive-relational study. A total of 1083 students constituted the group of the research. The data were collected through the Morningness-Eveningness Questionnaire (MEQ) and General Health Questionnaire and a questionnaire consisting of some questions about sleep. In the evaluation of data, multiple regression, mediation and path analysis were performed. Age, having problems affecting sleep, difficulties falling asleep, sharing the room with someone else and lack of leisure activities were related to bedtime. It was found that determinants of sleep quality were the variables related to sleep itself. Being a male student, having problems affecting sleep, difficulties falling at sleep, waking up during the night, getting support in the morning for waking up and lack of leisure activities negatively affected mental health. MEQ scale was interpreted as a determinant of sleep time, sleep quality, and mental health level. Although the MEQ score directly affected sleep quality, bedtime had a partial mediation role between MEQ score and sleep quality. Sleep quality had a full mediation role between MEQ score and mental health score. School health workers, especially nurses, should consider chronotype-focused measures to improve adolescents' sleep quality and psychosocial health.

An Optimal Time for Treatment-Predicting Circadian Time by Machine Learning and Mathematical Modelling

Tailoring medical interventions to a particular patient and pathology has been termed personalized medicine. The outcome of cancer treatments is improved when the intervention is timed in accordance with the patient's internal time. Yet, one challenge of personalized medicine is how to consider the biological time of the patient. Prerequisite for this so-called chronotherapy is an accurate characterization of the internal circadian time of the patient. As an alternative to time-consuming measurements in a sleep-laboratory, recent studies in chronobiology predict circadian time by applying machine learning approaches and mathematical modelling to easier accessible observables such as gene expression. Embedding these results into the mathematical dynamics between clock and cancer in mammals, we review the precision of predictions and the potential usage with respect to cancer treatment and discuss whether the patient's internal time and circadian observables, may provide an additional indication for individualized treatment timing. Besides the health improvement, timing treatment may imply financial advantages, by ameliorating side effects of treatments, thus reducing costs. Summarizing the advances of recent years, this review brings together the current clinical standard for measuring biological time, the general assessment of circadian rhythmicity, the usage of rhythmic variables to predict biological time and models of circadian rhythmicity.