S and full research articles published in SLEEP, the official journal of the APSS. Sleep and sleep disorder scientific findings.

Heart rate variability (HRV) is an objective marker that provides insight into autonomic nervous system dynamics. There is conflicting evidence regarding the presence of HRV impairment in insomnia patients. Web-based databases were used to systematically search the literature for all studies that compared the HRV of insomnia patients to controls or reported the HRV of insomnia patients before and after an intervention. 22 relevant papers were identified. Study characteristics were summarised, HRV measures were extracted and a risk of bias assessment for each study was performed. We were limited in our ability to synthesise outcome measures and perform meta-analyses due to considerable differences in patient (and control) selection, study protocols, measurement and processing techniques and outcome reporting. Risk of bias was deemed to be high in the majority of studies. As such, we cannot confirm that HRV is reliably impaired in insomnia patients nor determine the HRV response to interventions. Whilst HRV impairment in insomnia is a widely accepted concept, it is not supported by empirical evidence. Large longitudinal studies incorporating 24-hour recordings are required to elucidate the precise nature of HRV dynamics in insomnia patients.

Background Cognitive behavioral therapy (CBT) is an efficacious intervention for generalized anxiety disorder (GAD). Digital CBT may provide a scalable means of delivering CBT at a population level. We investigated the efficacy of a novel digital CBT program in those with GAD for outcomes of anxiety, worry, depressive symptoms, sleep difficulty, wellbeing, and participant‐specific quality of life. Methods This online, two‐arm parallel‐group superiority randomized controlled trial compared digital CBT with waitlist control in 256 participants with moderate‐to‐severe symptoms of GAD. Digital CBT (Daylight ), was delivered using participants’ own smartphones. Online assessments took place at baseline (Week 0; immediately preceding randomization), mid‐intervention (Week 3; from randomization), post‐intervention (Week 6; primary endpoint), and follow‐up (Week 10). Results Overall, 256 participants were randomized and intention‐to‐treat analysis found Daylight reduced symptoms of anxiety compared with waitlist control at post‐intervention, reflecting a large effect size (adjusted difference [95% CI]: 3.22 [2.14, 4.31], d = 1.08). Significant improvements were found for measures of worry; depressive symptoms, sleep difficulty, wellbeing, and participant‐specific quality of life. Conclusion Digital CBT (Daylight ) appears to be safe and efficacious for symptoms of anxiety, worry, and further measures of mental health compared with waitlist control in individuals with GAD.