Extending Sleep Improves Sleep and Stress Measures With Limited Microbiome Shift.

Poor sleep quality and duration are associated with adverse health. However, these can be remediated by experimental sleep extension. While the physiological mechanisms underlying the benefits of experimental sleep extension are unknown, recent evidence has highlighted the role of the gut microbiome in sleep physiology, potentially via the gut microbiome and inflammatory pathways. This pilot study examined whether extending sleep for 2 weeks would improve sleep, reduce stress and inflammation, and alter gut microbiome composition. Healthy female adults underwent a 2-week baseline assessment, followed by a 2-week sleep extension intervention. Pre- and post-intervention assessments included actigraphy, subjective sleep quality, perceived stress, salivary cortisol, interleukin-6 (IL-6), and gut microbiome profiling. Sleep extension increased total sleep time and time in bed without compromising sleep efficiency. Participants reported reductions in perceived stress and improved sleep quality, with large effect sizes. Skeletal muscle mass increased significantly, though no statistically significant changes were observed in cortisol or IL-6. While microbial diversity remained unchanged, linear discriminant analysis effect size analysis revealed a significant increase in the relative abundance of Peptostreptococcus, a genus implicated in producing indoleacrylic acid, a tryptophan-derived metabolite with anti-inflammatory and gut barrier-enhancing properties. Our findings suggest that increases in sleep duration can yield psychological, physiological, and microbiome-related benefits, supporting sleep extension as an intervention to improve stress-related health outcomes.