In one experiment, a man who didn't sleep for a week ended up sobbing about an imaginary gorilla. This episode explores what science has uncovered about the effects of sleep deprivation, from hallucinations to frank psychosis – and whether the brain recovers afterwards.

The inventor of Corn Flakes believed cinnamon was morally suspicious and flavour was a threat to virtue. This episode explores the strange story of John Harvey Kellogg, his wellness empire, his obsession with chewing, vibrating chairs for constipation, and why evolution made flavour far too appealing for his crusade to succeed.

In 1980, flight attendants began apparently sweating blood on flights between New York and Florida. The CDC investigated. The explanation was not what anyone expected. Also featuring blue sweat, pink sweat, and the only diagnostic dilemma ever solved by a dermatologist ringing a snack-food manufacturer.

This episode explores the biology of itching. Including NASA’s emergency Velcro patches, exploding lice in World War I trenches, contagious scratching, "amphetamites", mosquito mouth-javelins, and the imaginary insects produced by the human brain itself.

This episode explores what urine can reveal about you — from pregnancy and diabetes to drugs, disease, and genetic disorders. Including ancient Egyptian pregnancy tests, beetroot-induced panic, blue urine pranks, and why IKEA once asked women to wee on their catalogue.

This episode examines the odd biology and even odder rituals surrounding sneezing. Including sunlight sneezes, chocolate sneezes, and why on earth we feel compelled to bless them.

For thousands of years, doctors believed urine revealed the hidden workings of the body. By peering at a patient’s wee, they diagnosed everything from epilepsy to death — sometimes without even meeting the patient.

This episode explores the strange history of uroscopy, the rise of the “piss prophets”, and why modern doctors still occasionally ask you for a wee sample today.

If you were feeling sickly 100 years ago, your doctor might have prescribed a loincloth, a bed, and a sun-drenched balcony in the Swiss Alps. No blood tests or scans — your degree of tan would determine your prognosis.

From sun worship to sun-gazing to Coco Chanel accidentally making bronzed skin chic, this episode explores the many ways medicine and mankind have misunderstood the sun.