Effect of cognitive behavioural therapy and yoga for generalised anxiety disorder on sleep quality in a randomised controlled trial: the role of worry, mindfulness, and perceived stress as mediators.

Sleep disturbances are present in ~65% of individuals with generalised anxiety disorder (GAD). Although both Kundalini yoga (KY) and cognitive behavioural therapy (CBT) are effective treatment options for GAD, little is known about how these treatments compare in improving sleep for GAD and what drives these changes. Accordingly, we examined the effects of CBT, KY, and stress education (SEdu; an attention control condition) on subjective sleep quality (as measured by the Pittsburgh Sleep Quality Index [PSQI] and Insomnia Severity Index [ISI]) in a randomised controlled trial of 226 adults with GAD (mean age 33.37 years; 70% female; 79% White). We hypothesised that both CBT and KY would outperform SEdu in improving sleep disturbances. Three potential mediators of sleep improvement (worry, mindfulness, perceived stress) were also examined. In line with hypotheses, PSQI and ISI scores significantly improved from pre- to post-treatment for all three treatment groups (all p < 0.001, all d > 0.97). However, contrary to predictions, sleep changes were not significantly greater for CBT or KY compared to SEdu. In mediation analyses, within-person deviations in worry, mindfulness, and stress each significantly mediated the effect of time on sleep outcomes. Degree of change in sleep attributable to worry (CBT > KY > SEdu) and perceived stress (CBT, KY > SEdu) was moderated by treatment group. Personalised medicine as well as combined treatment approaches should be studied to help reduce sleep difficulties for patients with GAD who do not respond.

Treatment-related changes in insomnia, anticipatory pleasure, and depression symptoms: A proof-of-concept study with cancer survivors.

OBJECTIVE/BACKGROUND: Cancer survivors have elevated rates of insomnia and depression. Insomnia increases risk for depression onset, and the Integrated Sleep and Reward (ISR) Model suggests that impairments in reward responding (e.g., ability to anticipate and/or experience pleasure) plays a central role in this relationship. Cognitive behavioral therapy for insomnia (CBT-I) is efficacious for treating chronic insomnia and reducing depression in cancer survivor populations. The effects of CBT-I on anticipatory and consummatory pleasure are theoretically and clinically meaningful, yet remain unexamined. PATIENTS/METHODS: This secondary analysis of a pilot RCT (N = 40 cancer survivors with insomnia) explicated changes in anticipatory and consummatory pleasure and depression symptoms following a 4-session, synchronous, virtual CBT-I program versus enhanced usual care (referral to a behavioral sleep medicine clinic + sleep hygiene handout). Linear mixed models examined changes in anticipatory and consummatory pleasure and depression symptoms as predictors of changes in insomnia severity from baseline to post-intervention and 1-month follow-up. RESULTS: CBT-I buffered against deterioration in anticipatory pleasure but not consummatory pleasure or depression symptoms. Across conditions, increased anticipatory pleasure was associated with insomnia reduction through 1-month follow-up, even after adjusting for changes in depression symptoms. CONCLUSION: CBT-I may improve reward processing deficits in cancer survivors with insomnia. Findings provide support for the ISR Model and implicate pleasure as an important target for insomnia and depression.

Effects of the COVID-19 pandemic on anhedonia, reward exposure and responsiveness, and sleep in college students.

Objective: The COVID-19 pandemic's effects on college student mental health and its underlying mechanisms are not fully understood. Although necessary, physical distancing abruptly restricts interaction with environmental rewards and disrupts sleep patterns, both of which may contribute to psychological symptoms (eg, depression and anhedonia). This study explored differences in psychological symptoms, reward exposure and responsiveness, and sleep before versus during the pandemic. Methods: Eighty-seven college students completed baseline questionnaires and a one-week daily diary paradigm. The sample was divided into two groups based on data collection before (pre-) or after (post-COVID-19) implementation of state-wide COVID-19 physical distancing measures. Results: Findings highlight higher anhedonia, decrements in exposure to social, professional, and exercise related rewards, lower aniticipatory reward responsiveness, and lower sleep efficiency among college students during the initial months of the pandemic. Conclusions: Findings suggest anhedonia, reward system functioning, and sleep may be important targets to mitigate against college student mental health sequelae during COVID-19.

Relationships Among Sleep Disturbance, Reward System Functioning, Anhedonia, and Depressive Symptoms.

Recent models propose reward system dysfunction as a key mediator of the relationship between sleep and depression and anhedonia. This study explored interrelationships among sleep disturbance, depressive symptoms, anhedonia, and reward responsiveness. Two-hundred and sixty undergraduate students completed questionnaires and a daily diary paradigm assessing sleep, reward responsiveness, depression, anhedonia, and positive affect over 1 week. Baseline sleep disturbance was associated with depressive symptoms, anhedonia, and reward responsiveness. Daily diary sleep parameters showed differential associations with anticipatory versus consummatory reward responsiveness and positive affect. Poorer sleep quality, shorter sleep duration, and longer awakening after sleep onset predicted blunted anticipatory and consummatory reward responsiveness, while increased sleep onset latency and lower sleep efficiency predicted only decreased consummatory reward responsiveness. All sleep indices, except sleep onset latency, were associated with positive affect. Findings demonstrate unique associations between disparate sleep disturbance and reward responsiveness elements, highlighting new treatment mechanisms for anhedonia and depression.

Associations between insomnia and reward learning in clinical depression.

BACKGROUND: Depression and insomnia commonly co-occur. Yet, little is known about the mechanisms through which insomnia influences depression. Recent research and theory highlight reward system dysfunction as a potential mediator of the relationship between insomnia and depression. This study is the first to examine the impact of insomnia on reward learning, a key component of reward system functioning, in clinical depression. METHODS: The sample consisted of 72 veterans with unipolar depression who endorsed sleep disturbance symptoms. Participants completed the Structured Clinical Interview for DSM-IV, self-report measures of insomnia, depression, and reward processing, and a previously validated signal detection task (Pizzagalli et al., 2005, Biological Psychiatry, 57(4), 319-327). Trial-by-trial response bias (RB) estimates calculated for each of the 200 task trials were examined using linear mixed-model analyses to investigate change in reward learning. RESULTS: Findings demonstrated diminished rate and magnitude of reward learning in the Insomnia group relative to the Hypersomnia/Mixed Symptom group across the task. Within the Insomnia group, participants with more severe insomnia evidenced the lowest rates of reward learning, with increased RB across the task with decreasing insomnia severity. CONCLUSIONS: Among individuals with depression, insomnia is associated with decreased ability to learn associations between neutral stimuli and rewarding outcomes and/or modify behavior in response to differential receipt of reward. This attenuated reward learning may contribute to clinically meaningful decreases in motivation and increased withdrawal in this comorbid group. Results extend existing theory by highlighting impairments in reward learning specifically as a potential mediator of the association between insomnia and depression.