ESPE Yearbook of Paediatric Endocrinology

Brief summary: This cross-sectional and longitudinal study, nested in the Diabetes Care System cohort study from the West Friesland region of the Netherlands (n=990), assessed ‘social jet lag’ as the difference in midpoint of sleep in hours between weekdays and weekend days. Among working individuals with type 2 diabetes (T2D), this discordance between between social and biological rhythms (social jet lag) was associated with poor metabolic control. By contrast, among retired individuals, greater social jet lag was associated with better metabolic control.

Our body clocks integrate internal physiological and behavioral data (e.g. sleep time and wake-up schedules) and constantly try to align them with environmental factors in the best interest of overall health. While several studies showed a negative effect of disturbed synchronization of circadian rhythms on psychological and metabolic outcomes, less is known of this effect in T2D, especially also when considering possible confounders such as sex, age, education, work status, and diabetes complications. The presented study closes this gap in knowledge.

In this study, participants were categorized in three groups: low (≤1 hour; 35%), intermediate (44%) and high social jet lag (≥2 hours; 21%). Interesting findings that might concern not only T2D individuals, include: a) daily sleeping time was similar in all three groups, b) people with high social jet lag were younger and working, c) working people with higher social jet lag had worse metabolic disease markers (HbA1c, blood pressure, cholesterol ratio), while d) a mixed picture was observed in retired people with rather better disease markers in low and high social jet lag groups compared to intermediate group, and e) BMI was not associated with social jet lag in working people, but was negatively associated with social jet lag in retired persons.

Social jet lag is also a big subject for debate in adolescent medicine when it comes to topics such as sleep and fatigue, obesity, and school performance. The authors emphasise that age, lifestyle and working status matter when looking at the influence of social jet lag, and that the underlying mechanisms are complex and largely unknown. In a related commentary, Till Roenneberg writes (1): ‘While enforced social jetlag disrupts health, voluntary sleep extension on weekends might protect it.’ And: ‘A reduction of enforced social jetlag should therefore be central to strategies to prevent disease’; e.g. through more flexible work schedules, later school start times for adolescents or eliminating daylight saving time.

Reference: 1. How can social jetlag affect health? Till Roenneberg. Nature Reviews Endocrinology, Volume 19, July 2023: 383–384, 384. https://doi.org/10.1038/s41574-023-00851-2.