Physical Activity Linked With Better Sleep Quality, Heart Rate Variability in Adolescents

Physically inactive adolescents were more likely to have worse sleep quality and more heart rate variability than those who had regular physical activity, according to a study published in Sleep and Breathing. This reduction in sleep quality could have implications for cardiovascular health in this age group.

The cross-sectional study included adolescents of both genders. Adolescents were invited to participate after a parent or guardian gave informed consent. All participants were split into 2 groups based on sleep quality: good or poor. They were then further divided into subgroups: active good sleep quality (AGSQ), sedentary good sleep quality (SGSQ), active poor sleep quality (APSQ), and sedentary poor sleep quality (SPSQ).

Participants’ heart rate variability was obtained with a 12-lead electrocardiogram device. Blood pressure was also assessed. The International Physical Activity Questionnaire was used to record physical activity and the Pittsburgh Sleep Quality Index was used to assess sleep quality.

There were 352 adolescents who enrolled in the study, and they had a mean (SD) age of 15.8 (0.24) years. Most of the participants enrolled were girls (62%), 210 participants had good sleep quality, and 142 participants had poor sleep quality. The subgroups were divided, with 123 in AGSQ, 87 SGSQ, 36 APSQ, and 36 SPSQ.

The researchers found that participants in the SPSQ group had a higher mean (SD) systolic blood pressure (SBP) compared with AGSQ and SGSQ (119.4 [2.0] vs 112.8 [1.1] and 112.2 [1.24], respectively). The APSQ and SPSQ groups also had a higher mean (SD) diastolic blood pressure (DBP) compared with AGSQ (69.5 [0.8] and 68.8 [1.4] vs 65.3 [0.7]).

The investigators also examined several measures of heart rate variability, including root mean square of successive differences between normal heartbeats (RMSSD), pNN50, and SD1. There was a difference in the mean RMSSD between the SPSQ group and the AGSQ group (44.39 [5.29] vs 53.92 [2.75]). For pNN50, the SPSQ group had a significantly lower mean level than all of the other subgroups. There was a significant difference in SD1 in the nonlinear analysis, where SPSQ was less than APSQ (32.37 [3.72] vs 41.31 [1.89]).

An analysis of the frequency levels of the heart rate variability spectrum also demonstrated significant differences in all parameters. The low frequency percentage in the SPSQ group was higher than the AGSQ group (49.08 [2.79] vs 41.12 [1.45]) and the APSQ group was higher than the SGSQ group (49.66 [1.59] vs 44.21 [1.70]). The high frequency percentage was lower in the APSQ group compared with the AGSQ group (50.33 [1.52] vs 58.87 [1.45]).

The investigators summarized that the representative variables of the parasympathetic nervous system were at worse levels in the SPSQ group than in all other groups.

There was also a significant difference in SBP in female adolescents between the AGSQ group and SPSQ and APSQ groups (108.2 [1.4] vs 118.6 [2.5] and 116.3 [1.4]).

There were some limitations to this study. The investigators did not perform polysomnography to evaluate sleep in the adolescents and did not utilize other questionnaire tools, meaning that other comorbidities like insomnia and parasomnias could not be evaluated in this study.

“A physically active lifestyle could decrease the harmful effects of poor sleep for some variables involved with cardiovascular control,” the researchers concluded.

Reference

Soares NJS Jr, Dias-Filho CAA, Ferreira AC, et al. Sleep quality and regular physical activity in reducing cardiac risk. Sleep Breath. Published online August 3, 2022. doi:10.1007/s11325-022-02688-x