Circadian misalignment impacts cardiac autonomic modulation in adolescence

Area of Science:

• Cardiovascular Health
• Sleep Science
• Autonomic Nervous System Function

Background:

• Heart rate variability (HRV) is a key indicator of cardiac autonomic modulation (CAM) and a predictor of cardiovascular morbidity.
• Circadian timing of sleep (CTS) also influences autonomic modulation, suggesting a potential link between sleep patterns and cardiovascular health.

Purpose of the Study:

• To investigate the association between circadian misalignment and blunted HRV in adolescents.
• To examine these associations in relation to school entrainment and breaks.

Main Methods:

• Utilized actigraphy (ACT) and polysomnography (PSG) data from 360 adolescents (median age 16) in the Penn State Child Cohort.
• Assessed circadian misalignment using sleep midpoint (SM), sleep irregularity (SI), and social jetlag (SJL).
• Analyzed five 24-h, daytime, and nighttime HRV indices using linear regression models, adjusting for covariates and considering in-school/on-break status.

Main Results:

• Later weekend sleep midpoint (SM) during breaks was associated with all nighttime HRV indices.
• Greater weekday sleep irregularity (SI) during school was linked to multiple daytime and nighttime HRV indices.
• Social jetlag (SJL) was not significantly associated with any HRV index.

Conclusions:

• Adolescent circadian misalignment, characterized by irregular sleep during social demands and delayed sleep on free days, is associated with blunted HRV.
• Circadian misalignment may increase cardiovascular risk in youth by altering cardiac autonomic modulation.