Lack of sleep can make us sick, fat and slow. But what if a sleep disorder is to blame? What happens when no matter how much sleep you get, it's never enough?

In the last of a three-part series, neurologist Dr Guy Leschziner explores medical causes of sleep deprivation or disruption and their consequences. We meet some of his patients, including 17 year-old Vincent, whose internal body clock runs on a different rhythm from the world around him, leaving him wide awake when everyone else is tucked up in bed. We hear from Mary Rose, whose restless legs stop her from getting to sleep and staying asleep and Claire, whose severe insomnia led to a breakdown. And we talk to Maria, whose mysterious symptoms turned out to be due to one of the most common sleep disorders, sleep apnoea.

In this programme, we learn about the medical causes of lack of sleep and the serious impact that these conditions have on our brain function, mood and general health.

Presenter: Dr Guy Leschziner
Producer: Sally Abrahams. Show less