On Monday 28 October, Anne Skeldon, visited the Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research (SBIDER), a cross-disciplinary institute hosted by the Mathematics Institute at the University of Warwick, and gave a talk in the SBIDER Seminar series. The title of her talk was “Mathematical modelling of the sleep-wake cycle: light, clocks and digital-twins“. As part of the talk, she gave a background to mathematical modelling of sleep-wake regulation and an overview of the different ways that her group is using mathematical models to tackle real world questions (daylight saving time, school start times, jetlag, sleep timing disorders, fatigue risk management). She then talked about some of her recent work analysing models of wake and sleep but included the cycling between rapid eye movement sleep and non-rapid eye movement sleep. Underlying everything is her on-going strong collaboration with the Surrey Sleep Research Centre and particularly the director, Derk-Jan Dijk.While there she took the opportunity to catch up with David Rand  and Robert Dallmann. Below is a screenshot of the front page of the Zeeman Insitute website.