Anne Skeldon visited the University of Durham on Monday this week (17 November) where she was invited to give a talk in the Applied Mathematics Seminar series. The title of her talk was “Mathematical modelling of the sleep-wake cycle: light, clocks and digital-twins” (Durham page with abstract). This talk continues the themes of Anne‘s long-standing collaboration with Derk-Jan Dijk and others at the Surrey Sleep Research Centre. She discussed the non-smooth coupled oscillator systems that form the basis of current mathematical models of sleep-wake regulation and their dynamics. Their most recent endeavour is to work towards digital-twinning approaches for helping those with sleep timing problems.