A Pilot Observational Study to Assess the Ability of Continuous 'Home' EEG to Accurately Diagnose Narcolepsy and Demonstrate Response to Treatment

The goal of this pilot observational study is to assess the ability of continuous 'home' EEG to accurately diagnose Narcolepsy in children and young people with hypersomnia. The main question\[s\]it aims to answer are: * can ambulatory home monitoring using a Dreem headband with a 'life as usual' unrestricted protocol allow accurate diagnosis of Narcolepsy, compared to gold standard in-patient PSG and MSLT * which EEG derived sleep parameters and study duration yield most diagnostic accuracy Participants undergoing investigation for hypersomnia will additionally be asked to wear a Dream Headband at night for weeknights, then continuously for 48 hours over the weekend. The data from the headband will then be analysed to see if it can predict the results of the polysomnography and MSLT that form routine clinical care.