This cluster of papers encompasses a wide range of research on sleep and insomnia, including topics such as the epidemiology of insomnia, the effects of sleep duration on health, cognitive behavioral therapy for insomnia, and the psychometric evaluation of sleep measures. It also covers the impact of sleep on various health outcomes, including cardiovascular disease, diabetes, obesity, and mental health. Additionally, the cluster includes studies on the role of circadian rhythms and sleep quality in overall well-being.