The paper “Method to determine whether sleep phenotypes are driven by endogenous circadian rhythms or environmental light by combining longitudinal data and personalised mathematical models“, co-authored by Anne Skeldon, Thalia Rodriguez Garcia, Sean Cleator, Ciro Della Monica (SSRC, Surrey), Kiran K G Ravindran (SSRC, Surrey), Victoria Revell (SSRC, Surrey), and Derk-Jan Dijk (SSRC, Surrey), has been published in PLOS Computational Biology (link to OA published version). This landmark paper emerged from a joint project between Surrey Mathematics, the Surrey Sleep Research Centre (SSRC), and the Dementia Research Institute. Sean Cleator was formerly a Post-doc at Surrey and is now a Data Scientist at Volant Autonomy in Bristol. The three main features of the paper are (1) they put together a new model for sleep-wake regulation; (2) they suggest a new measure for quantifying the effect of one day of light on our human biological clock, taking into account that the effect depends on both the intensity and time; and (3) they show that it is possible to create “personalised” models which match individual sleep timing and duration. The image below is Figure 3 from the paper.