Dados do Trabalho

Título

Chronotype is associated with heart rate variability

Introdução

In modern society, many individuals show conflict between circadian preferences and social schedules (working hours, early morning classes), so that the most affected are evening-type individuals. These individuals suffer a sleep debt, due to sleep deprivation on weekdays, trying to compensate on weekends by extending sleep, delayed start and midpoint times of sleep. This phenomenon is called social jetlag (SJL). Literature shows that sleep deprivation is associated with cardiovascular risk factors. Thus, SJL may be a measure of chronic sleep deprivation in these individuals and may indicate changes in the autonomic nervous system’s control over the cardiovascular system. These changes in the autonomic nervous system can be measured by heart rate variability.

Objetivo

The aim of this study was to investigate whether there is an association between SJL and chronotype with heart rate variability in university students.

Métodos

Volunteers answered the following questionnaires: Munich Chronotype Questionnaire (MCTQ), Morningness-Eveningness Questionnaire (MEQ), Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI) and were submitted to EKG monitoring, Bioimpedance, and Actigraphy.

Resultados

The study had a final sample of 65 individuals, 63.1% female and 36.9% male. In the comparison between groups for SJL it was identified that individuals with SJL ≥ 2 hours had worse sleep quality when compared with individuals with SJL <2 hours. The groups did not present statistical differences on daytime sleepiness, anthropometric data and HRV parameters. Correlation tests showed correlation between MEQ score and heart rate (r = - 0.350; p = 0.005), RMSSD index (r = 0.278; p = 0.026), SDNN index (r = 0.281; p = 0.024) and RR intervals (0.346; p = 0.005).

Conclusões

This work suggests that eveningness is associated to reduction of HRV. However, no relation between SJL and HRV was found.

Palavras-chave

Chronotype, social jetlag, cardiovascular risk