Claudia Hammond's guest is Catherine Loveday, Principle lecturer in Psychology at the University of Westminster

If you have sisters or brothers you probably know all about sibling rivalry. But if you're a parent who despairs over your children squabbling, fear not. Claudia Hammond hears how sibling rivalry can be handled and can have an upside. It's something that should be embraced argues child psychologist Linda Blair, author of a new book Siblings.

What insights can diaries and letters from prisoners of war can give us into the imprisoned soldier's minds? We hear from historian Clare Makepeace who has spent years studying the diaries and letters of POWs and Mark McDermott Professor of Health Psychology at the University of East London to discuss the psychological impact the confined experience can have.

And new evidence on the link between inflammation in the body and depression. It's the first study ever published showing that inflammation can lead to alterations in how specific new brain cells are formed - a process that leads to depression in a third of patients. As Patricia Zunszain of Kings College London explains, drugs targeting these mechanisms could be the effective antidepressants of the future - drugs which don't tackle mood, but which encourage the creation of new brain cells.