SLEEP PATTERNS

By Professor Francesco Cappuccio, Warwick Medical School

In the second article of our series 'The Impact of Data on Body and Mind', Professor Francesco Cappuccio, Warwick Medical School, explains how modern society has been digitally enabled to work and play 24/7, and the effect that this has on our sleep patterns.

Throughout our life we spend approximately a third of our time asleep. We spend more time asleep as babies and children and then settle for a pattern that is of approximately 7 to 8 hours per night. Although subjective sleep duration remains fairly constant with age, sleep patterns indicate that total sleeping time, sleep efficiency, and deep sleep decline, and waking after sleep onset increases as we get older. Sufficient sleep is necessary for optimal daytime performance and well-being, yet there is a large difference in how much sleep people report, ranging from <6 hours to >9 hours per night. The epidemiology of sleep duration indicates that a good night’s sleep equates to at least 6 hours of continuous sleep, with changes in sleep duration or continuity being associated with negative impacts on health.

...it is estimated that over the next 20 years, the number of Americans suffering from sleep disorders will double.

Sleep disturbances and sleep deprivation are common in modern society. Most studies show that since the beginning of the century, populations have been subjected to a steady constant decline in the number of hours devoted to sleep, due to changes in a variety of environmental and social conditions (e.g. less dependence on daylight for most activities, extended shift work, 24/7 round-the-clock activities). The detrimental effects to health of sustained sleep deprivation and disruption were first acknowledged by industry (like airlines, long-distance driving, shift-work manufacturing industry, and emergency services). Only recently, however, has the wider implication for the population at large been unveiled. Through the application of epidemiological methods of investigation, short duration of sleep has been associated with a variety of chronic conditions and poor health outcomes, detectable across the entire lifespan, from childhood to adulthood to older age, most noticeably an increase in obesity, high blood pressure, diabetes, stroke, coronary heart disease and mortality.

As the world population increases and individuals become larger, the number suffering from sleep disorders will increase. In the United States, it is estimated that over the next 20 years, the number of Americans suffering from sleep disorders will double. However, the public awareness of the need for adequate sleep both for adults and children and the awareness of sleep-related conditions are poor. Moreover, the physicians who treat them receive minimal training in sleep disorders medicine. In fact, they themselves are forced to endure excessive work schedules during their internship and residency training, which desensitizes them to sleep as a fundamental biological necessity, degrades their ability to provide quality patient care and to benefit fully from their training experience, and places them at increased risk of ill-health, injuries, and sleep-related motor vehicle accidents during their training. These difficult, and often conflicting, interests need to be addressed so that the medical field can provide an optimal platform for learning and patient care.

The public awareness of the importance of sleep, the need for good sleep hygiene and awareness of sleep disorders in general is poor in both adults and children. Various professional bodies worldwide are attempting to redress the balance. In the UK education system, for example, children are taught about the importance of diet and exercise but sleep education is rarely addressed. Poor sleep habits in early life may have long-term consequences for health.

These issues bring the results of the epidemiology of sleep outside the clinical setting and well within the domain of public health. One of the main questions still to answer is whether in these circumstances, sleep disturbances are the consequence of ill-health, are intermediate markers in the pathways of disease causation, or whether changes in sleep patterns can be causal in the determination of chronic disease and, more generally, ill-health. At the same time, the deleterious effects of shift work, like risk of self-harm and harm to others (e.g. medical errors, road accidents, attentional failures in high risk occupations), which are by and large mediated by excessive sleepiness and fatigue caused by sleep debt, have recently benefited from stronger evidence from randomized clinical trials and are now informing policy changes.

Francesco Cappuccio moved to Warwick in July 2005 to take up the newly established Cephalon Chair in Cardiovascular Medicine & Epidemiology. He is a cardiovascular physician, a clinical epidemiologist and a public health expert. After his medical degree in Naples, he moved to Britain where he trained at Charing Cross Hospital, St George's Hospital Medical School and the London School of Hygiene & Tropical Medicine in London. In 2000 he became Professor of Clinical Epidemiology & Primary Care at St George's, University of London.

His main interests are in the prevention, detection and management of hypertension and its complications of the heart, brain, kidneys and the circulation. His research interests are the epidemiology of cardiovascular disease, nutrition and health, metabolic abnormalities and cardiovascular risk, risk in ethnic minorities, both in developed and developing countries.

Franco heads up a multi-disciplinary research group with a number of research objectives: to develop and establish a programme of national and international cardiovascular epidemiology, to develop and establish a significant national and international programme of research into Sleep, Health and Society, to facilitate clinical research into sleep disorders, to assist the development of undergraduate and postgraduate education into sleep medicine and its impact on health and society.