You can fly, turn invisible or ride a giraffe through an airport in your dreams. But there are three perfectly ordinary activities that almost never make an appearance. This episode explores a bizarre peculiarity of dreaming, what it might tell us about the evolution of the human brain, and why even Freud probably didn't want to hear about your dreams.

Pain is miserable, but living without it is considerably worse. This episode explores the extraordinary lives of people born unable to feel pain, from a 1930s vaudeville performer (the "Human Pincushion") to a man who had both legs amputated without painkillers, to discover why pain hurts quite so much – and why your survival depends on it.

How do you know whether you’re actually asleep? People with paradoxical insomnia can spend the night convinced they’re wide awake, while their brainwaves insist otherwise.

This episode explores what happens when your experience of sleep disagrees with the electrical evidence, why the sleeping brain may be more awake than we once thought, and whether you might actually be getting more sleep than you realise.

This episode explores how drugs, foods, poisons, cosmetics and assorted bodily malfunctions can produce human skin in all 7 colours of the rainbow (and how Isaac Newton is to blame for us thinking a rainbow has 7 colours in the first place).

Dehydration. Too much water. Too much exercise. Not enough exercise. Apparently almost anything can cause a muscle cramp. This episode explores why your muscles occasionally seize without permission, what your nervous system has to do with it, and whether magnesium actually helps.

How can the hunk of meat in your mouth ‘know’ what the food smeared over it tastes like? This episode explores what actually makes something sweet, sour, salty, bitter or umami, and what maggot-infested cheese, antifreeze and a poisoned Roman emperor have to do with it.

Spoiler alert: yes. A nosebleed may have finished off one of history's most feared warlords. This episode explores why noses bleed so dramatically, the ingenious anatomy hidden inside your nostrils, exactly what to do the next time your nose starts gushing... and one of the strangest nosebleed case reports ever published.

Your blood is always red. So why the bruise rainbow? This episode explores the colourful chemistry of bruises, from love bites and cupping to creatures with blue, green and yellow blood - and what Tiffany & Co.'s famous turquoise packaging has to do with it.