Social jetlag is associated with adverse cardiometabolic latent traits in early adolescence: an observational study.

Introduction: Adolescence is marked by physiological and social changes, such as puberty, increased responsibilities and earlier school start times. This often leads to insufficient sleep on school nights and the need to compensate for lost sleep on weekends, causing a misalignment between biological and social times, which has been termed social jetlag (SJL). SJL triggers stress responses and is associated with several negative health outcomes, including higher cardiometabolic risk in adults.

Latitudinal cline of chronotype.

The rotation of the Earth around its own axis and around the sun determines the characteristics of the light/dark cycle, the most stable and ancient 24 h temporal cue for all organisms. Due to the tilt in the earth's axis in relation to the plane of the earth's orbit around the sun, sunlight reaches the Earth differentially depending on the latitude. The timing of circadian rhythms varies among individuals of a given population and biological and environmental factors underlie this variability.

Interactions of polymorphisms in different clock genes associated with circadian phenotypes in humans.

Several studies have shown that mutations and polymorphisms in clock genes are associated with abnormal circadian parameters in humans and also with more subtle non-pathological phenotypes like chronotypes. However, there have been conflicting results, and none of these studies analyzed the combined effects of more than one clock gene. Up to date, association studies in humans have focused on the analysis of only one clock gene per study.

The G619A Aa-nat gene polymorphism does not contribute to sleep time variation in the Brazilian population.

Genes involved in melatonin synthesis, such as Aa-nat, may be important for our understanding of diurnal preference and circadian rhythm disturbances in humans. In Japan, Hohjoh et al. reported increased allelic frequencies of the 619A allele of the G619A Aa-nat gene polymorphism in a sample of Delayed Sleep Phase Syndrome (DSPS) patients.

Clock polymorphisms and circadian rhythms phenotypes in a sample of the Brazilian population.

A Clock polymorphism T to C situated in the 3' untranslated region (3'-UTR) has been associated with human diurnal preference. At first, Clock 3111C had been reported as a marker for evening preference. However these data are controversial, and data both corroborating and denying them have been reported.

Sleep patterns of day-working, evening high-schooled adolescents of São Paulo, Brazil.

Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students.