Depression, multiple sclerosis (MS) and epilepsy are all disorders of the central nervous system. While the symptoms and disability experienced by individuals with each condition are different, they all have a significant effect on people’s wellbeing. For doctors and people with these long-term (chronic) conditions, understanding how their disease changes over time can help with its management. But in chronic conditions most of the symptoms and episodes happen outside of the health care environment. Measuring individuals’ symptoms, mood and daily function continuously, could help people gain better insight into their condition.