nature communication: “11 million days of longitudinal Fitbit data reveal novel future health insights”
https://www.nature.com/articles/s41467-026-78529-2_reference.pdf
https://www.nature.com/articles/s41467-026-78529-2_reference.pdf
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(25)02219-6/fulltext