Linking autonomic nervous system reactivity with sleep in adolescence: Sex as a moderator.

The purpose of the present study was to investigate relations between autonomic nervous system (ANS) reactivity across the parasympathetic and sympathetic branches and multiple sleep parameters in adolescence. Participants were 244 adolescents (Mage  = 15.79 years old, SD = 9.56 months; 67.2% White/European-American, 32.8% Black/African-American). Parasympathetic activity was indexed by respiratory sinus arrhythmia (RSA) withdrawal and sympathetic activity was indexed by skin conductance level reactivity (SCL-r), which were examined in response to a laboratory-based stressor (star-tracing task). Sleep was assessed with actigraphs in adolescents' homes for seven consecutive nights. Two sleep parameters were examined: sleep duration indexed by actual sleep minutes and sleep quality indexed by sleep efficiency from sleep onset to wake time. Regression analyses showed that more RSA withdrawal (lower RSA during task than baseline) was associated with shorter sleep, and more SCL-r (higher SCL during task than baseline) was associated with poorer sleep efficiency. Moderation analyses showed that associations linking RSA withdrawal with fewer sleep minutes and poorer sleep efficiency, and SCL-r with fewer sleep minutes were significant only for boys. Results illustrate that higher daytime physiological reactivity (increased RSA withdrawal and SCL-r) is negatively associated with sleep duration and efficiency for adolescents, especially boys.