Declaration of conflicts of interest We acknowledge the generous support of the Harvard Radcliffe Institute, whose mission to develop innovative and interdisciplinary research made the prosecution of this project possible. RR reports consulting fees from Sonesta Hotels International, Oura Ring Ltd, byNacht GmbH, and Castle Hot Springs. RR reports funding from Bryte Foundation, the Casey Feldman Memorial Foundation, and Google. EBK reports consulting fees from American Academy of Sleep Medicine Foundation, Circadian Therapeutics, National Sleep Foundation, Sleep Research Society Foundation, Yale University Press. EBK reports travel support from the European Biological Rhythms Society, Sleep Research Society, and EPFL Pavilions. Scientific Advisory Board: (unpaid) Chronsulting. EBK (Other): Partner is the founder, director, and chief scientific officer of Chronsulting. MDW reports consulting fees from the Fred Hutchinson Cancer Center and the University of Pittsburgh. MDW reports travel support provided to attend the symposium on Daylight Saving Time from the Radcliffe Institute for Advanced Study at Harvard University. CAC serves as the incumbent of an endowed professorship provided to Harvard Medical School by Cephalon, Inc and reports institutional support for a Quality Improvement Initiative from Delta Airlines and Puget Sound Pilots; education support to Harvard Medical School Division of Sleep Medicine and support to Brigham and Women’s Hospital from: Jazz Pharmaceuticals PLC, Inc, Philips Respironics, Inc, Optum, and ResMed, Inc; research support to Brigham and Women’s Hospital from Axsome Therapeutics, Inc, Dayzz Ltd, Peter Brown and Margaret Hamburg, Regeneron Pharmaceuticals, Sanofi SA, Casey Feldman Foundation, Summus, Inc, Takeda Pharmaceutical Co, LTD, Abbaszadeh Foundation, CDC Foundation; educational funding to the Sleep and Health Education Program of the Harvard Medical School Division of Sleep Medicine from ResMed, Inc, Teva Pharmaceuticals Industries, Ltd, and Vanda Pharmaceuticals; personal royalty payments on sales of the Actiwatch-2 and Actiwatch-Spectrum devices from Philips Respironics, Inc; personal consulting fees from Axsome Therapeutics, Bryte Foundation, With Deep, Inc and Vanda Pharmaceuticals; honoraria from the Associated Professional Sleep Societies, LLC for the Thomas Roth Lecture of Excellence at SLEEP 2022, from the Massachusetts Medical Society for a New England Journal of Medicine Perspective article, from the National Council for Mental Wellbeing, from the National Sleep Foundation for serving as chair of the Sleep Timing and Variability Consensus Panel, for lecture fees from Teva Pharma Australia PTY Ltd and Emory University, and for serving as an advisory board member for the Institute of Digital Media and Child Development, the Klarman Family Foundation, and the UK Biotechnology and Biological Sciences Research Council. CAC has received personal fees for serving as an expert witness on a number of civil matters, criminal matters, and arbitration cases, including those involving the following commercial and government entities: Amtrak; Bombardier, Inc; C&J Energy Services; Dallas Police Association; Delta Airlines and Comair; Enterprise Rent-A-Car; FedEx; Greyhound Lines, Inc and Motor Coach Industries and FirstGroup America; PAR Electrical Contractors, Inc; Puget Sound Pilots; the San Francisco Sheriff’s Department; Schlumberger Technology Corp; Union Pacific Railroad; United Parcel Service; and Vanda Pharmaceuticals. CAC has received travel support from the Stanley Ho Medical Development Foundation for travel to Macao and Hong Kong; equity interest in Vanda Pharmaceuticals, With Deep, Inc, and Signos, Inc; and institutional educational gifts to Brigham and Women’s Hospital from Johnson and Johnson, Mary Ann and Stanley Snider via Combined Jewish Philanthropies, Alexandra Drane, DR Capital, Harmony Biosciences, LLC, San Francisco Bar Pilots, Whoop, Inc, Harmony Biosciences LLC, Eisai Co, LTD, Idorsia Pharmaceuticals LTD, Sleep Number Corp, Apnimed, Inc, Avadel Pharmaceuticals, Bryte Foundation, f.lux Software, LLC, Stuart F. and Diana L. Quan Charitable Fund. Dr Czeisler's interests were reviewed and are managed by the Brigham and Women's Hospital and Mass General Brigham in accordance with their conflict-of-interest policies.