Abstract

World Health Organization (WHO) estimates reveal that over 777 million people were reportedly infected by SARS-CoV-2, with approximately 7 million deaths and 770 million surviving the disease up to April 2025. Beyond the immediate social and economic impact, an additional challenge arises as a large percentage of COVID-19 survivors report a wide range of symptoms after the acute phase, including fatigue, shortness of breath, cognitive difficulties, joint and muscle pain, chest pain, heart palpitations, loss of taste or smell, headaches, depression, anxiety, and sleep and circadian alterations. In this chapter, we will specifically address the sleep- and circadian rhythm-related alterations within this context. First, we will focus on sleep-related changes following the acute phase of the disease, detailing their manifestations, prevalence, and associated factors. We will then discuss the potential impact of these sleep-related aspects on the risk of SARS-CoV-2 infection, the severity of COVID-19, and the presence of post-COVID-19 conditions. A similar approach will be applied to address the circadian-related alterations. Finally, we will provide a comprehensive discussion on the overall limitations of available knowledge and its applicability, highlighting the relevance of these findings for the present and future. © 2025 Thieme Medical Publishers, Inc.. All rights reserved.