@@CHAP@@ Introduction
Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.
Marie Skłodowska-Curie
Forty years ago, as an undergraduate studying zoology at the University of Bristol, I knew I wanted to be a scientist, but I had little real idea of what that meant or involved. The ‘body clock’ was just a fuzzy concept in my young, unfocused free-wheeling brain. However, during the final year of my undergraduate degree, I was a volunteer helper at an international meeting on biological rhythms. The job was not demanding, and I swanned about listening to the lectures and met the then leaders of the field. With the confidence – perhaps arrogance – of youth, I assumed that these scientific titans would want to speak to me just as much as I wanted to speak to them. Most were incredibly generous with their time, although I did learn not to approach one very senior professor over breakfast (it’s amazing how much meaning can be conveyed in a stony silence and a fixed stare at a greasy sausage …). It was a formative experience at many levels, and I soaked up the science like a sponge. Without my knowing it, this symposium defined my life-long interests and sparked an ambition to join this extraordinary group of international academics who were working on the fast-emerging science of biological time. My career as a scientist, from my undergraduate days to my current position as Professor of Circadian Neuroscience and Director of the Sir Jules Thorn Sleep and Circadian Neuroscience Institute at Oxford has allowed me to gain insights from, and occasionally share new knowledge with, colleagues from all over the globe. In a sense, this book represents the distillate of what I have learnt in studying the nature of biological time over the course of four decades. My hope is that I can convey to you some of the excitement, wonder and undiluted pleasure I have experienced over the years.
In the past few decades, there has been an explosion of thrilling new discoveries in and around the science of the body clock and the 24-hour biological cycles that dominate our lives. The most obvious of these cycles is the daily pattern of sleep and wake. Surprisingly, most books discuss the body clock and sleep separately. However, new research tells us that such a disconnected approach tells only part of the story. You cannot properly understand sleep without understanding the body clock, and sleep in turn regulates the clock. In the pages that follow, the body clock and sleep will be considered together as two intimately linked and intertwined areas of biology that define and dominate our health. In so many cases, your ability to succeed or fail, from driving home safely after work or dieting to achieve weight loss, will depend upon whether you are working with or against these 24-hour cycles. So much has happened in this area of science and medicine that it is often difficult to disentangle fact from fiction. In terms of health, sensible advice is frequently transformed into strident orders that resemble the commands shouted by a Regimental Sergeant Major on the parade ground: you ‘must’ get eight hours of sleep; you ‘must’ continue to share a bed with a partner who snores; you ‘must not’ use a light-emitting eReader (LE-eBook) before bed. So rather than being recognized as a loyal friend, biological rhythms and sleep are frequently portrayed as the enemy that needs to be wrestled, subdued and defeated. Instead, we need to understand and embrace these rhythms.
In this book, I have attempted to unpack the science of body clocks and sleep, making some of the amazing and exciting discoveries accessible, and hopefully in a format that is fun and easy to read. I have been able to draw from my own personal experiences over the past forty years as a scientist in this field, and have benefited immensely from discussions with friends and colleagues, who have contributed directly to our current understanding of biological time. I provide the evidence behind our current knowledge of the science, and how this evidence can be used by each of us to make more informed decisions about improving our lives. From getting better sleep, to organizing our daily activities and even why we may benefit from taking medications or being vaccinated at a particular time of day. The information in this book will also give you a greater understanding of the behaviour of others, including why teenagers and the elderly might struggle to get restorative sleep, why your mood and decision-making skills may change from morning to afternoon, and why the risk of divorce is higher in those doing night shift work. I have emphasized throughout this book that we are all very different, and that while it is possible to make generalizations, taking an ‘average value’ can be misleading. Although the average length of the menstrual cycle in women is 28 days, only 15 per cent of women actually have a 28-day cycle. Your body clock and sleep biology can be likened to your shoe size: one size does not fit all, and making us all wear the same shoe size would be not only foolish but potentially harmful. The failure to recognize this variation is why some general advice in the media can be either overly simplistic or deeply unhelpful.