A systematic review and narrative synthesis of the complex interplay between psychological flexibility and sleep health

Sleep has been recognised as a growing health concern, with research suggesting a link between psychological flexibility, a core concept in Acceptance and Commitment Therapy (ACT), and sleep-related outcomes. While previous work has outlined correlational associations, the complexity of these relationships remains poorly understood. Our systematic review aims to comprehensively elucidate the nuanced interplay between psychological flexibility and sleep health alongside implications of their relationships across diverse populations.

We carried out searches in four electronic databases (PsycInfo, MEDLINE, EMBASE, and CINAHL) on February 9th, 2024. Following title and abstract screening, 209 full texts were screened and 29 studies that met our inclusion criteria were identified. A narrative synthesis was conducted to synthesise data from the included studies.

Psychological flexibility was identified as an important predictor of sleep health, with acceptance and cognitive defusion emerging as particularly critical components of psychological flexibility. The majority of studies examined psychological flexibility as a predictor, mediator, and moderator, with a minority exploring the role of sleep as a risk and protective factor. Moreover, there was evidence of additional risk factors beyond flexibility, namely anxiety sensitivity dimensions, in predicting poor sleep-related outcomes.

Our review highlights the complexity of the relationships between psychological flexibility and sleep health. Despite measurement considerations impacting the interpretation of findings, our results provide foundations for future research endeavours aimed at refining theoretical models, designing targeted interventions, and ultimately improving sleep health, psychological flexibility, and mental well-being for individuals facing various psychological and physiological challenges.