Sleep disorders

The term sleep disorder (somnipathy) simply means a disturbance of an individual’s normal sleep pat­tern. Doctors typically see patients in whom the dis­turbance is having a negative effect upon physical, mental, or emotional functioning, but subclinical dis­turbances of sleep are common and something almost everyone will suffer at some point in their life. Sleep disorders are a heterogeneous group, ranging from the frequently experienced insomnia to the extremely rare hypersomnias such as Kleine– Levin syndrome. However, there are many shared characteristics and this chapter will concentrate mainly on providing a framework for assessment, diagnosis, and manage­ment in the generic sense, with some guidance on spe­cific disorders in the latter sections. A good working knowledge of basic sleep disorders is essential in all specialties of clinical medicine. As a general rule, sleep disorders within the general hos­pital environment tend to be poorly managed, with great detriment to the patient. There are a variety of reasons why it is important to be able to diagnose and treat sleep disorders: … ● Epidemiology: sleep disorders are very common and affect all ages. ● Co- morbidities: sleep disturbances may be a primary disorder or secondary to a mental or physical disorder. They are often prodromal symptoms of psychiatric conditions. ● Impact upon physical health: poor sleep is linked to increased mortality and morbidity from many pathologies (see ‘Consequences of inadequate sleep’, p. 405). ● Medications (not just psychotropics) often affect sleep. ● Sleep disturbance is an important part of many primary psychiatric conditions (e.g. mood disorders, psychosis, anxiety disorders); further information on these can be found in the chapter relating to each disorder. … Sleep is a natural state of bodily rest seen in humans and many animals and is essential for survival. It is different from wakefulness in that the organism has a decreased ability to react to stimuli, but this is more easily reversible than in hibernation or coma. Sleep is poorly understood, but it is likely that it has several functions relating to restoration of body equilibrium and energy stores. There are a variety of theories re­garding the function of sleep, which are outlined in Box 28.1.