Prior research in ALSPAC has shown that sleep problems in adolescence are associated with subsequent depression and anxiety (doi:10.1111/jcpp.13288). However, there is still much we do not understand about the complex relationship between sleep and mental health in young people. First, most genetic studies have been conducted in older adults (aged 40 years or older), with less research examining genetic influences on sleep in young people. Second, sleep problems appear to affect mental health more in some people than others but there is limited research exploring which factors influence these individual differences. This project will examine associations between sleep and depression/anxiety across adolescence and young adulthood and focus on the following areas: (i) whether genetic factors previously associated with sleep problems in adults are also associated with sleep problems in adolescence/young adulthood, and (ii) whether associations between sleep problems and anxiety/depression are influenced by genetic factors. Results from this work will impact our current understanding of the role sleep disturbance plays in the onset and recurrence of mood and anxiety disorders, in addition to informing mental health interventions and treatments.