More than 50 people crammed into a small intimate room in the back of Bristol’s Tobacco Factory – not in front of any PowerPoint slides or microphones, just a Professor of Medicine holding a pint… On Monday 27 April, Professor Stafford Lightman took us through what makes us keep eating, sleeping and waking – with a stark public health warning.

 In 1962, a French caver decided to study the movement of a glacier through an underground cave. Though he knew he’d be shrouded in darkness, Michael Siffre decided to carry out an experiment and left his watch behind. For two months he woke, slept and ate in the darkness. His assistants took and analysed each of his urine and stool samples to monitor his health. Despite having lost track of all time, Michael still followed a 24-hour pattern of waking, eating, sleeping and doing it all over again.

What Michael didn’t know, according to Professor Stafford Lightman, is that he had a watch all along – and it was in his brain. A tiny pea-sized “master clock” called the suprachiasmatic nucleus or SCN, sits in the middle of our brain, telling different parts of our body how to function over a 24-hour period. Much of the signals given off by the SCN affect the hypothalamo-pituitary-adrenal (HPA) axis, the complex set of interactions between three major endocrine glands: the hypothalamus, pituitary and the adrenal.

It wasn’t the usual format for a Science Cafe. There were no PowerPoint slides or microphones, just a Professor of Medicine holding a pint and drawing diagrams on a whiteboard. No questions were off limits and a quick-fire succession of separating fact from fiction followed:

• Yes, periods shut down when women are under prolonged periods of stress and have low body fat.
• No, taking melatonin does not always help you go to sleep.
• No, hitting the snooze button will not mess with your cortisol levels.
• We are unlikely to ever find a miracle pill for jet lag. Insomnia is a very difficult condition and doctors know very little about it.

 But Stafford didn’t just come to dispel myths; he had a stark health warning for our 21st century habits. There are two hugely important phases in a human’s life where their brain is making new connections at breaking speed: around the first year of life and in adolescence. We sleep more at both these stages in life because our brains need the additional resting time. One of the factors that disrupt our sleep cycle is blue light, which tells our brain that it is still daylight. More and more adolescents are using smartphones and tablets before going to bed and so soaking up a huge amount of blue light that affects the quality of their sleep at a critical point in their lives. Are new generations likely to adapt to this or is it a ticking public-health time bomb? Stafford reckons it’s the latter.

 Professor Stafford Lightman spoke at a Science Cafe event,  held on Monday 27 April, organised by the Bristol and Bath branch of the British Science Association. Science Cafes are held the last Monday of every month in the Tobacco Factory and on Wednesdays at Halo Cafe.

 If you want to learn more about circadian rhythms and how we’re driven by stress, the Society for Endocrinology is hosting a one-off event at this year’s Times Cheltenham Science Festival with eminent Professor Jonathan Seckl. For more information check out our public events page.