Effects of Post-Exposure Naps on Change in Autonomic Arousal to a Social Challenge Across Exposure Therapy for Social Anxiety

Abstract

Sleep promotes memory consolidation and regulates emotion. Sleep may strengthen therapeutic extinction learned during exposure therapy. We investigated effects of post-exposure naps on pre- to post-treatment changes in autonomic arousal during an experimental social stressor in people with Social Anxiety Disorder. Twenty-six participants aged 18-39 (16 females) with mean Liebowitz Social Anxiety Scale scores of 85 (96% > 60) completed a five-session group exposure therapy for social anxiety. A modified Tier Social Stress Test (mpTSST) was conducted before and after treatment. Heart rate (HR) and skin conductance level (SCL) were measured during the baseline, performance (speech and mental math), and recovery periods of the mpTSST. Heart rate variability (HRV) measures using time domain and frequency domain analysis with ratio of low- to high-frequency HR oscillations (sympathovagal balance) were computed. The third and fourth therapy sessions concluded with a speech exposure followed by either a 120-minute nap opportunity (nap, 14Ss) or a non-arousing video (wake, 11Ss). The nap group showed greater pre- to post-treatment decrease in SCL during and while recovering from the social stressor, F(1, 23) = 4.54, p < .05. The post- compared to pre-treatment SCL during mpTSST decreased in the nap group (p < .05) but not the wake group. There was a trend toward decrease in standard deviation of all successive R-to-R intervals (SDNN) across treatment, F(1, 21) = 4.67, p < .05, but no group differences. Although the pre-to-post treatment main effect for sympathovagal balance was not significant, a near trend was seen for the Time x Group interaction, F(1, 21) = 2.57, p = .12, with sympathovagal balance decreasing in the nap group—the same pattern that was seen for the other sympathetic activity index, SCL. Thus, therapy with post-exposure naps was associated with greater reduction in sympathetic activation to a social stressor from pre-to post treatment. Sleep augmentation of exposure therapy may benefit the treatment of Social Anxiety Disorder.