Horizon reveals the science behind our perception of colour, a highly subjective illusion.

The Ebola virus. No-one knows exactly where it comes from but one thing is certain - it\\\\\\\'s one of the most virulent infections known to science. This special episode of Horizon meets the scientists and doctors from all around the world looking for the cure and hears first-hand accounts of what it\\\\\\\'s actually like to catch - and survive - this terrible disease.

Horizon follows the emotional journey of three young people with currently untreatable conditions to see if, within their lifetime, they can be cured.

You might think that your memory is there to help you remember facts, such as birthdays or shopping lists. If so, you would be very wrong. The ability to travel back in time in your mind is, perhaps, your most remarkable ability, and develops over your lifespan.

Each year millions of people's lives are improved by the use of tissue from the dead. Bodies are used to supply spare parts, and for surgeons to practice on. Horizon investigates the medical revolution that has created an almost insatiable demand for body parts and uncovers the growing industry and grisly black market that supplies human bodies for a price.

Dr Kevin Fong finds out how doctors can avoid making mistakes in the high-pressure, high-stakes world of the operating theatre.

The quest to live longer has been one of humanities oldest dreams, but while scientists have been searching, a few isolated communities have stumbled across the answer. On the remote Japanese island of Okinawa, In the Californian town of Loma Linda and in the mountains of Sardinia people live longer than anywhere else on earth. In these unique communities a group of scientists have dedicated their lives to trying to uncover their secrets. Horizon takes a trip around the globe to meet the people who can show us all how to live longer, healthier lives.

We are bad at making decisions. According to science, our decisions are based on oversimplification, laziness and prejudice. And that's assuming that we haven't already been hijacked by our surroundings or led astray by our subconscious!

Dr Kevin Fong finds out how close scientists are to being able to mend your heart if it stops working. He meets some of the people who have undergone pioneering heart operations and the scientists who are pushing the limits of cardiac treatment.

Is there any way to slow or even prevent the ravages of time? Veteran presenter Johnny Ball looks back over the 45 years that Horizon - and he - have been on air to find out what science has learned about how and why we grow old.

Recent research has analysed the link between the harmful effects of drugs relative to their current classification by law with some startling conclusions. Perhaps most startling of all is that alcohol, solvents and tobacco (all unclassified drugs) are rated more dangerous than ecstasy, 4-MTA and LSD (all class A drugs). If the current ABC system is retained, alcohol would be rated a class A drug and tobacco class B.

Horizon explores the strange and wonderful world of illusions - and reveals the tricks they play on our senses and why they fool us.

Dr Michael Mosley and Professor Alice Roberts investigate if male and female brains really are wired differently.

Transplant surgery has now reached incredible heights, from achieving full face transplants to growing organs in the lab. This Horizon Guide looks back at the extraordinary odds doctors and patients have had to overcome to achieve these amazing breakthroughs.

Dr Kevin Fong explores a medical revolution that promises to help us live longer, healthier lives. Inspired by the boom in health-related apps and gadgets, it's all about novel ways we can monitor ourselves around the clock. How we exercise, how we sleep, even how we sit.

A look at people living with OCD, the therapy available and what neuroscience can offer.

Friendly bacteria, superfoods, cholesterol busting spreads, 99% germ free, whiter than white...it's almost impossible to find a product in the supermarket today that doesn't come with impressive claims, scientific claims with an inflated price tag to match. Are they oversold? Or are they worth the extra cash?

In 1992 the nuclear industry celebrated its 50th anniversary and the report on the accident at Chernobyl claimed there was no evidence of long term health effects. Within months, a team of western scientists presented a very different picture with evidence of an epidemic of thyroid cancers in local children.

They are the miracle pills that shouldn\'t really work at all. Placebos come in all shapes and sizes, but they contain no active ingredient. Now they are being shown to help treat pain, depression and even alleviate some of the symptoms of Parkinson\'s disease. Horizon explores why they work, and how we could all benefit from the hidden power of the placebo.

Why are you more likely to have a heart attack at eight o'clock in the morning or crash your car on the motorway at two o'clock in the afternoon? Can taking your medication at the right time of day really save your life? And have you ever wondered why teenagers will not get out of bed in the morning?

Horizon reveals the latest research into one of the most mysterious and common human experiences - pain.

Like many, Michael Mosley want to get fitter and healthier but can't face hours on the treadmill or trips to the gym. Help may be at hand.

Plastic surgeon Dr Rozina Ali leaves the operating theatre behind for the frontiers of skin science and asks if it is possible to make your skin look younger without surgery.

Taste is our most indulgent sense but it is only in recent years that we have started to understand why we really love the foods we do - and it is a lot more surprising than you might think.

Could you have come up with Einstein\'s theory of relativity? If not - why not?

Dallas Campbell delves into the Horizon archive to discover how our understanding of intelligence has transformed over the last century. From early caveman thinkers to computers doing the thinking for us, he discovers the best ways of testing how clever we are - and enhancing it.

The world is affected by an obesity epidemic, but why is it that not everyone is succumbing? Medical science has been obsessed with this subject and is coming up with some unexpected answers. As it turns out, it is not all about exercise and diet. At the centre of this programme is a controversial overeating experiment that aims to identify exactly what it is about some people that makes it hard for them to bulk up.

Horizon uncovers the secret world of our dreams. In a series of cutting-edge experiments and personal stories, we go in search of the science behind this most enduring mystery and ask: where do dreams come from? Do they have meaning? And ultimately, why do we dream?

Talking is something that is unique to humans, yet it still remains a mystery. Horizon meets the scientists beginning to unlock the secrets of speech - including a father who is filming every second of his son\'s first three years in order to discover how we learn to talk, the autistic savant who can speak more than 20 languages, and the first scientist to identify a gene that makes speech possible.

Professor Robert Winston presents his top ten scientific breakthroughs of the past 50 years. Tracing these momentous and wide-ranging discoveries, he meets a real-life bionic woman, one of the first couples to test the male contraceptive pill, and even some of his early IVF patients. He explores the origins of the universe, probes the inner workings of the human mind and sees the most powerful laser in the world.