Long COVID as a Risk Factor for Hypersomnolence and Fatigue: Insights from the 2nd International Covid Sleep Study Collaboration (ICOSS-2)

Authors

• Tomi Sarkanen, Tampere University
• Ilona Merikanto, University of Helsinki
• Bjørn Bjorvatn, University of Bergen
• Frances Chung, University of Toronto
• Brigitte Holzinger, Medical University of Vienna
• Charles M. Morin, Université Laval
• Thomas Penzel, Charité Universitätsmedizin Berlin
• Luigi De Gennaro, Sapienza University of Rome
• Yun Kwok Wing, The Chinese University of Hong Kong
• Christian Benedict, Uppsala University
• Pei Xue, Uppsala University
• Catia Reis, Universidade Católica Portuguesa
• Maria Korman, Gulbenkian Institute for Molecular Medicine
• Anne-Marie Landtblom, Uppsala University
• Kentaro Matsui, National Center of Neurology and Psychiatry
• Harald Hrubos-Strøm, Akershus University Hospital
• Sérgio Mota-Rolim, Federal University of Rio Grande do Norte
• Michael R. Nadorff, Mississippi State University
• Linor Berezin, University of Toronto
• Yaping Liu, The Chinese University of Hong Kong
• Serena Scarpelli, Sapienza University of Rome
• Luis E. M. Brandao, Uppsala University
• Jonathan Cedernaes, Uppsala University
• Eemil Partinen, University of Helsinki
• Courtney J. Bolstad, Birmingham VA Health Care System
• Giuseppe Plazzi, IRCCS Istituto delle Scienze Neurologiche di Bologna
• Colin A. Espie, University of Oxford
• Markku Partinen, University of Helsinki Clinicum Unit
• Yves Dauvilliers, University of Montpellier

ORCID

Sarkanen: https://orcid.org/0000-0001-8815-2807; Bolstad: https://orcid.org/0000-0003-2297-2778

MSU Affiliation

College of Arts and Sciences; Department of Psychology

Creation Date

2026-06-30

Abstract

BACKGROUND: Hypersomnolence, defined as excessive daytime sleepiness (EDS), excessive quantity of sleep (EQS), sleep inertia, and fatigue reduce quality of life. We assessed associations of the COVID-19 pandemic, infection without long-term sequalae (short COVID, SC), and long COVID (LC) on hypersomnolence and fatigue in a large population across different countries. METHODS: As part of an online questionnaire (ICOSS-2), we assessed EDS via the Epworth Sleepiness Scale (ESS), fatigue via Fatigue Severity Scale (FSS), and sleep duration at night and per 24 h. We also assessed the associations with EDS, sleep inertia, fatigue and napping by their frequencies, during the pandemic in COVID-negative, SC and LC participants. RESULTS: The final cohort comprised 13,656 participants (69.1 % women, 42.7 ± 16.6 years), with 12.4 % classified SC and 7.5 % LC. ESS scores were higher in LC (9.16, 95 % CI [8.78, 9.53]) compared to SC (7.26, [6.97, 7.55]) and COVID-negative (6.53, [6.43, 6.63]). LC also had higher odds of ESS>10 (OR 1.58, [1.18,2.09]). FSS scores were higher in LC (median 51, IQR 39-59) than SC (34, 25-44) and COVID-negative (35, 25-45), with LC having 2.22 higher odds of severe fatigue. LC cases also reported more EQS (≥10/24 h) than COVID-negative. Worsening of EDS, fatigue, sleep inertia, and napping was reported during pandemic to a greater extent in LC. CONCLUSIONS: LC was associated with higher levels of hypersomnolence and fatigue than in SC or COVID-negative participants, highlighting the need for interventions and future research focusing on sleep symptoms and their relation to long-term health outcomes.

Publication Date

10-21-2025

Publication Title

Sleep Medicine

Publisher

Elsevier

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Rights

© 2025 The Authors

Recommended Citation

Sarkanen, T., Merikanto, I., Bjorvatn, B., Chung, F., Holzinger, B., Morin, C. M., Penzel, T., De Gennaro, L., Wing, Y. K., Benedict, C., Xue, P., Reis, C., Korman, M., Landtblom, A.-M., Matsui, K., Hrubos-Strøm, H., Mota-Rolim, S., Nadorff, M. R., Berezin, L., … Dauvilliers, Y. (2025). Long COVID as a risk factor for hypersomnolence and fatigue: Insights from the 2nd International Covid Sleep Study Collaboration (ICOSS-2). Sleep Medicine, 136, 106764. https://doi.org/10.1016/j.sleep.2025.106764