To sleep, perchance to dream... of maths

We all sleep: but what is it? How much do you need? Are you a `lark' or an `owl'? What is `social jetlag' and do you suffer from it? In this talk I will introduce some of the basic ideas behind the mathematical modelling of sleep/wake regulation. I will show how models can be used to investigate policy questions, such as whether or not we should switch to permanent daylight savings time or delay school start times for adolescents, and explore how long it takes to recover from jetlag.