Waking up to the importance of sleep

For decades, sleep and its associated disorders have been considered a Cinderella branch of medicine. The subject receives little attention in undergraduate education, training is an adjunct to other more established specialties, and funding for sleep research is woefully deficient. The reasons for such neglect are embedded in the disparate nature of the conditions grouped together under the heading of sleep disorders—ranging from sleep apnoea, dealt with by an ear, nose, and throat specialist or cardiologist, to restless legs syndrome, handled by a neurologist or primary care physician—as well as a lack of understanding of their causes and the sparsity of treatment options. However, things are beginning to change. Partly responsible for this shift were three scientists who won the Nobel Prize for Medicine or Physiology in 2017 for their work on the genetic basis of circadian rhythms. Thanks to the discoveries of Michael Rosbash, Jeffrey Hall, and Michael Young, we now know that humans have a molecular clock—a network of timekeeping genes and associated proteins that are transcribed, translated, and degraded in a daily cycle. These genes have also been found to be associated with bipolar disorder, depression, and other mood disorders. Some sleep disorders have been discovered to be markers of Parkinson's disease, Lewy body dementia, and multiple system atrophy. Additionally, the development of portable monitoring devices has enabled practitioners to assess sleep in real-world environments including the home. Finally, the elucidation of the pathophysiology of narcolepsy—caused by the selective loss of neurons that secrete the wake-promoting neuropeptide orexin—has led to the development of novel drugs for insomnia. Building on this progress, The Lancet and The Lancet Neurology today publish a four-paper Series that systematically examines various sleep disorders, as well as reviewing the anthropology of sleep. Despite the diverse nature of sleep disorders, the Series delivers four key messages. First, sleep disorders are an underappreciated public health problem. They are very common, cause much distress to both sufferers and their bed partners, and have far-reaching effects on population health and economic wellbeing. For example, insomnia occurs in up to a third of adults. Excessive daytime sleepiness can reduce productivity and safety in the workplace. In the classroom, children's education suffers, and on the roads, up to a third of traffic accidents are caused by sleep deprivation. Second, patients are being failed by the lack of effective treatment options. Drug treatments are easily prescribed for insomnia, for instance—most notably benzodiazepines and the so-called Z-drugs, such as zopiclone, eszopiclone, and zaleplon; however, non-pharmacological approaches, such as those based on cognitive behavioural therapy, are considered first-line treatment but are often not widely available. Furthermore, use of talking therapy does not risk the development of medication dependence, which is common with long term use of drugs prescribed for sleep disorders. Sleep hygiene, which has increasingly gained the attention of the public, can be a key part of such cognitive behavioural therapies. Third, in both hospital and primary care settings, physicians need to be aware of the chronic effects of poor sleep on general medical conditions such as hypertension, diabetes, and heart disease. Both insufficient and excessive sleep will have substantial detrimental effects on many common health conditions, increasing both morbidity and mortality. Enquiry about sleep should therefore be an integral part of any medical consultation. Finally, rates of insufficient sleep and sleep disorders are highly likely to rise. For example, anthropological investigation has shown that insomnia is inextricably linked with modern life (insomnia occurs in 10–30% of people living in industrialised societies compared with less than 2% in hunter-gatherer populations in Namibia and Bolivia). Psychosocial stressors, alcohol consumption, smoking, and lack of exercise are associated with sleep disturbance. Additionally, increased use of technological devices—particularly smart phones among younger people—in the bedroom around the time of sleep leading to exposure to blue light, is considered a potential cause of sleep–wake rhythm disorders. For an activity that takes up a third of every human being's life, sleep has received, hitherto, much less attention than it deserves by physicians, health-care professionals, and policy makers. This Series should serve as a wake up call to all about the importance of good sleep and the fact that studying, assessing, and treating its disorders should receive greater prominence in modern medicine. Circadian rhythms and disorders of the timing of sleepThe daily alternation between sleep and wakefulness is one of the most dominant features of our lives and is a manifestation of the intrinsic 24 h rhythmicity underlying almost every aspect of our physiology. Circadian rhythms are generated by networks of molecular oscillators in the brain and peripheral tissues that interact with environmental and behavioural cycles to promote the occurrence of sleep during the environmental night. This alignment is often disturbed, however, by contemporary changes to our living environments, work or social schedules, patterns of light exposure, and biological factors, with consequences not only for sleep timing but also for our physical and mental health. Full-Text PDF Understanding and approaching excessive daytime sleepinessExcessive daytime sleepiness (EDS) is a public health issue. However, it remains largely undervalued, scarcely diagnosed, and poorly supported. Variations in the definition of EDS and limitations in clinical assessment lead to difficulties in its epidemiological study, but the relevance of this symptom from a socioeconomic perspective is inarguable. EDS might be a consequence of several behavioural issues leading to insufficient or disrupted sleep, as well as a consequence of sleep disorders including sleep apnoea syndrome, circadian disorders, central hypersomnolence disorders (narcolepsy and idiopathic hypersomnia), other medical or psychiatric conditions, or medications. Full-Text PDF InsomniaInsomnia is highly prevalent in clinical practice, occurring in up to 50% of primary care patients. Insomnia can present independently or alongside other medical conditions or mental health disorders and is a risk factor for the development and exacerbation of these other disorders if not treated. In 2016, the American College of Physicians recommended that insomnia be specifically targeted for treatment. The recommended first-line treatment for insomnia, whether the underlying cause has been identified or not, is cognitive behavioural therapy for insomnia (CBT-I). Full-Text PDF