Claudia Hammond talks to Professor Christopher French from Goldsmiths, University of London about the strange phenomenon of sleep paralysis. As many as 1 in 20 people will experience vivid hallucinations while falling asleep or waking up while also completely unable to move. People also describe a very powerful sense of fear and the feeling of being crushed or that an intruder or something supernatural is there with them. Despite being relatively common, this sleep anomaly is little understood. Even less well known or understood is the frightening experience of 'Exploding Head Syndrome' where someone perceives abrupt and very loud noises when going to sleep or waking up.

Also can a robot deliver therapy via your smartphone? Claudia talks to Alison Darcy - Stanford University researcher who's created Woebot - an artificially intelligent chatbot designed to treat depression. Woebot, uses cognitive-behavioural therapy and is available via Facebook messenger. Alison explains how it works and that it's not a replacement for traditional therapy, but it's the first tech based treatment to have been properly scientifically tested and peer reviewed..

Simon Wessley, outgoing president of the Royal College of Psychiatrists, and Paul Farmer, chief executive of the mental health charity MIND discuss mental health awareness campaigns with Claudia. Do they overload already stretched mental health services? Or are they vital to helping people understand their own mental health and are they changing the wider landscape of how these conditions are understood, talked about and de-stigmatised?