Why evening-types accumulate health issues and die younger than others?

Description du projet

Pourquoi les noctambules s’exposent-ils à un risque caché pour leur santé?

Certaines personnes se lèvent naturellement avec le soleil, d’autres vivent la nuit. Ces préférences innées, connues sous le nom de types circadiens, déterminent notre sommeil, notre vigilance et même nos cycles hormonaux. Mais ceux qui «sont du soir» courent un risque ignoré: ils sont plus susceptibles de développer des problèmes de santé, de l’enfance à l’âge adulte. Le projet ChronoHealth, financé par le CER, va étudier les raisons de cette situation. La biologie est-elle en cause? Ou est-ce notre monde moderne, avec ses heures rigides d’école et de travail, qui impose aux noctambules un rythme qui ne leur convient pas? S’appuyant sur un ensemble exceptionnel de données génétiques, comportementales et environnementales allant de la petite enfance à la vieillesse, ChronoHealth entend démêler l’interaction du mode de vie, de l’environnement et de la génétique pour façonner la santé à long terme.

Objectif

Individuals differ in daily timing of sleep–wake behavior, alertness, body temperature, cardiovascular functions and hormonal secretion, having innately different circadian types from morningness to eveningness. Evening-types show poorer health already since childhood with increasing severity of health issues at adulthood with major impact on performance/wellbeing and health care burden. However, it is largely unknown WHY health issues accumulate to evening-types. It is likely that underlying factors for health differences between circadian types include interplay between biological, behavioral and environmental factors. Project uses large population-based longitudinal and cross-sectional data across life span from early childhood to old age linked to national register data, including wellbeing and health surveys, objective circadian assessment, health measurements and genetic data. I will study which environmental, behavioral and biological factors influence circadian rhythms and their disturbances throughout life span and how these moderate/mediate the association between circadian type and health/wellbeing outcomes. Focus during early childhood will be in somatic and cognitive development, during adolescence in school adjustment, life habits and somatic/mental wellbeing, and during adulthood in disorders, hospital treatments, and mortality. I will examine the role of genetic predisposition, family/school/work/social environment, life habits and behavioral schedules. Besides the unique and versatile data available for the research, novel objective tools for assessing circadian misalignment is developed in the project. Along with my expertise on circadian research, this project has versatile data and statistical power to sort out whether health issues among evening-types are more due to biological liability, such as genetic risk, or due to e.g. higher risk for circadian desynchronization as behavioral and societal schedules are in mismatch with the innate rhythms.