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This study aimed to test the generalizability of the model to other sleep schedules, including rotating shift work. Ambulatory wrist blue light irradiance and skin temperature data were collected in 16 healthy individuals on fixed and habitual sleep schedules, and 28 rotating shift workers. Artificial neural network models were trained to predict the circadian rhythm of (i) salivary melatonin on a fixed sleep schedule; (ii) urinary aMT6s on both fixed and habitual sleep schedules, including shift workers on a diurnal schedule; and (iii) urinary aMT6s in rotating shift workers on a night shift schedule. To determine predicted circadian phase, center of gravity of the fitted bimodal skewed baseline cosine curve was used for melatonin, and acrophase of the cosine curve for aMT6s. On a fixed sleep schedule, the model predicted melatonin phase to within\u2009\u00b1\u20091\u2009hour in 67% and\u2009\u00b1\u20091.5\u2009hours in 100% of participants, with mean absolute error of 41\u2009\u00b1\u200932\u2009minutes. On diurnal schedules, including shift workers, the model predicted aMT6s acrophase to within\u2009\u00b1\u20091\u2009hour in 66% and\u2009\u00b1\u20092\u2009hours in 87% of participants, with mean absolute error of 63\u2009\u00b1\u200967\u2009minutes. On night shift schedules, the model predicted aMT6s acrophase to within\u2009\u00b1\u20091\u2009hour in 42% and\u2009\u00b1\u20092\u2009hours in 53% of participants, with mean absolute error of 143\u2009\u00b1\u2009155\u2009minutes. Prediction accuracy was similar when using either 1 (wrist) or 11 skin temperature sensor inputs. These findings demonstrate that the model can predict circadian timing to within\u2009\u00b1\u20092\u2009hours for the vast majority of individuals on diurnal schedules, using blue light and a single temperature sensor. However, this approach did not generalize to night shift conditions.<\/jats:p>","DOI":"10.1038\/s41598-019-47311-4","type":"journal-article","created":{"date-parts":[[2019,7,29]],"date-time":"2019-07-29T10:21:36Z","timestamp":1564395696000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":33,"title":["Generalizability of A Neural Network Model for Circadian Phase Prediction in Real-World Conditions"],"prefix":"10.1038","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7706-7471","authenticated-orcid":false,"given":"Julia E.","family":"Stone","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew J. 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Dr Phillips is a co-investigator on a project for the CRC for Alertness, Safety and Productivity. Dr Ftouni served as a Project Leader in the CRC for Alertness, Safety and Productivity. Dr Magee served as a Project Leader in the CRC for Alertness, Safety and Productivity. Dr Sletten serves as a Project Leader in the CRC for Alertness, Safety and Productivity. Dr Anderson received a research award\/prize from Sanofi-Aventis; contract research support from VicRoads, Rio Tinto Coal Australia, National Transport Commission, Tontine\/Pacific Brands; and lecturing fees from Brown Medical School\/Rhode Island Hospital, Ausmed, Healthmed and TEVA Pharmaceuticals; and reimbursements for conference travel expenses from Philips Healthcare. In addition, she has served as a consultant to the Rail, Bus and Tram Union, the Transport Accident Commission (TAC), the National Transportation Committee (NTC), VicRoads and Melius Consulting. She has also served as an expert witness and\/or consultant in relation to fatigue and drowsy driving. Dr Anderson is a Theme Leader in the Cooperative Research Centre for Alertness, Safety and Productivity. Dr Howard serves as a Theme Leader in the CRC for Alertness, Safety and Productivity, which funded this work; and has received grants from Prevention Express, Resmed Foundation and TEVA, and equipment support for research from Optalert and Seeing Machines which are not related to the work reported in this paper. Dr Lockley has had a number of commercial interests in the last 3 years (2016\u201319). He is a Program Leader for the CRC for Alertness, Safety and Productivity, Australia, which funded this work. No other interests are directly related to the research or topic reported in this paper but, in the interests of full disclosure, are outlined below. Dr Lockley has received consulting fees from the Atlanta Falcons, Atlanta Hawks, BHP Billiton, Noble Insights, Slingshot Insights, and Team C Racing; honoraria and\/or paid travel from BHP Billiton, DIN, IES, Ineos, SLTBR, and Teague; has current consulting contracts with Akili Interactive; Apex 2100 Ltd.; Consumer Sleep Solutions; Delos Living LLC; Headwaters Inc.; Hintsa Performance AG; Light Cognitive; Lighting Science Group Corporation; Mental Workout; PlanLED; Six Senses; Stantec; and Wyle Integrated Science and Engineering; has received unrestricted equipment gifts from Bionetics Corporation and F. Lux Software LLC; royalties from Oxford University Press; and has served as a paid expert in legal proceedings related to light, sleep and health. He holds a patent through Harvard University and Brigham and Women\u2019s Hospital for \u2018Systems and methods for determining and\/or controlling sleep quality\u2019. Dr Rajaratnam is also a Program Leader for the CRC for Alertness, Safety and Productivity, Australia, which funded this work. Dr Rajaratnam reports grants from Vanda Pharmaceuticals, Philips Respironics, Cephalon, Rio Tinto and Shell, and has received equipment support and consultancy fees through his institution from Optalert, Tyco Healthcare, Compumedics, Mental Health Professionals Network, and Teva Pharmaceuticals, which are not related to this paper. Dr Postnova serves as a Theme Leader for the CRC for Alertness, Safety and Productivity.","order":1,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing Interests"}}],"article-number":"11001"}}