Western countries are the most sleep-deprived countries in the world. Insomniac Michael Mosley finds out what happens if we don't get enough sleep and looks at surprising solutions to help us get more.

Memory is the glue that binds our mental lives. Without it, we’d be prisoners of the present, unable to use the lessons of the past to change our future. From our first kiss to where we put our keys, memory represents who we are and how we learn and navigate the world. But how does it work? Neuroscientists using cutting-edge techniques are exploring the precise molecular mechanisms of memory". By studying a range of individuals ranging —from an 11-year-old whiz-kid who remembers every detail of his life to a woman who had memories implanted— scientists have uncovered a provocative idea. For much of human history, memory has been seen as a tape recorder that faithfully registers information and replays intact. But now, researchers are discovering that memory is far more malleable, always being written and rewritten, not just by us but by others. We are discovering the precise mechanisms that can explain and even control our memories. The question is— are we ready?

Angela Rippon and Dr Chris van Tulleken travel the world in search of the latest science that could help us all stay young and healthy for longer. They investigate the best ways to help both our bodies and brains age better. Up first is the body, and Angela travels to Germany to join a groundbreaking study which reveals the exercise that holds off ageing the most. Chris visits America to find out about the unexpected diet that can add years to our lives. And in Ecuador we meet a seventeen-year-old who looks like a child to discover how scientists hope he may hold the key to preventing the diseases of ageing.

This episode explores what can give brains a boost. In America, Angela tries out a new treatment that's proven to help memory and concentration. In Japan, a remarkable 100-year-old reveals the colourful foods that keep minds more active. Plus Chris discovers the best exercise we can do for our brains. At the cutting-edge of science, discover how injections of young people's blood may help beat dementia.

Horizon investigates the idea that the best way to lose weight successfully is a personalised approach, diets tailored to our individual biology and psychology. In a groundbreaking experiment, Dr Chris van Tulleken and Tanya Byron join a team of experts to put 75 overweight volunteers on diets designed to tackle the specific reasons why they eat too much. The volunteers are put through a series of tests at a residential clinic to understand how their genes, hormones and psychology influence their eating behaviour. They are then put on the diets the experts believe are best suited to them. Can science succeed where other diets have failed?

It is time to see if personalised dieting will work in normal life. The volunteers have been given one of three diets to follow - based on their genes, their hormones and their psychology. But now they are back at home, trying to stick to their personalised diets with all the stresses and temptations of real life. Dr Chris van Tulleken and Professor Tanya Byron discover how our genetic makeup can make temptation difficult to resist, how understanding the brain reveals what makes us comfort eat and what science can tell us about why we make disastrous food choices.