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Sleep disorders are common in all sections of the population and are either the main clinical complaint or a frequent complication of many conditions for which patients are seen in primary care or specialist services. However, the subject is poorly covered in medical education. A major consequence is that the manifestations of the many sleep disorders now identified are likely to be misinterpreted as other clinical conditions of a physical or psychological nature, especially neurological or psychiatric disorders. To illustrate this problem, examples are provided of the various possible causes of sleep loss, poor quality sleep, excessive daytime sleepiness and episodes of disturbed behaviour at night (parasomnias). All of these sleep disorders can adversely affect mental state and behaviour, daytime performance or physical health, the true cause of which needs to be recognised by clinicians to ensure that appropriate treatment is provided. As conventional history taking in neurology and psychiatry pays little attention to sleep and its possible disorders, suggestions are made concerning the enquiries that could be included in history taking schedules to increase the likelihood that sleep disorders will be correctly identified.
Sleep disorders are among the most common complaints seen by general practitioners. They also complicate very many conditions referred to specialist medical services. Awareness of the wide range of codified sleep disorders is increasing, but not fast enough, considering how common such disorders are and their often serious consequences. At any one time, approximately 30% of the general public are affected by a significant sleep problem,1 often of long standing, with much higher rates in certain groups such as the elderly,2 those with a psychiatric disorder3 or learning disability,4 and others who have neurological or other medical disorders.5 This overall pattern is true of children as well as adults.6 Persistent sleep loss or poor quality sleep affects emotional state and behaviour, cognitive function and performance at school or work, family cohesion and general quality of life, mental health and also physical well being.7 The total cost of these consequences in human and economic terms has been calculated to be enormous.8
The general public are still not particularly well informed, nor are healthcare professionals because of deficiencies in their training. A 1998 survey of UK medical schools revealed that out of a typical 5 year undergraduate course, the median time spent on formal teaching about sleep and its disorders was 5 min.9 There is no reason to believe that the situation has improved since then, and no evidence that the deficiency is corrected in higher training, even in specialties where the prevalence of sleep disorders is particularly high, such as paediatrics, psychiatry or geriatrics. Understandably, therefore, medical staff do not usually enquire about sleep symptoms10 and, where treatment is prescribed, there is still over reliance on medication, especially hypnotics, despite the well established drawbacks of their use.11
Similar shortcomings have been reported in the training of nurses12 and clinical psychologists13 who, in theory, are well placed to identify and, in some instances, treat sleep disorders. It is cold comfort that these shortcomings in professional training, and their consequences for standards of clinical care, are not confined to the UK but are reported in other countries, including the USA14 where sleep disorders medicine is generally better recognised than elsewhere.
This lack of adequate attention to sleep disorders is significant because there are many important points of direct relevance between the 90 or more sleep disorders now described in the recent second edition of the International Classification of Sleep Disorders,15 and other areas of clinical practice.
The present review is concerned with this last fundamental link between sleep disorders and clinical practice in neurology, psychiatry and, indeed, other specialties. The diagnostic points made about the examples selected are based on evidence in the form of personal and published clinical experience, including the results of reports for which specific references are provided.
Persistently not obtaining enough sleep, or having poor quality sleep because of frequent interruptions, or fragmentation by frequent subclinical arousals (as in OSA), is likely to cause tiredness, fatigue, irritability, poor concentration, impaired performance possibly causing injuries or accidents at work or while driving, or depression.7 Of the various possible explanations for such changes in behaviour, sleep disturbance may well be overlooked, with failure to appreciate that, with an improvement in sleep (which is usually possible with the correct advice), such problems will be resolved. Occupational groups at special risk of sleep disturbance and its harmful effects include some clinicians.19
Excessive sleepiness, whatever its cause out of the many possibilities, including physical conditions,20 is often misjudged as laziness, loss of interest, daydreaming, lack of motivation, depression, intellectual inadequacy, non‐convulsive seizures or a number of other unwelcome states of mind. Sometimes, in very sleepy states, periods of “automatic” behaviour occur (ie, prolonged, complex and often inappropriate behaviour with impaired awareness of events and, therefore, amnesia for them). Such episodes can easily be misconstrued as reprehensible or dissociative behaviour, or prolonged seizure states. The paradoxical effect in young children of sleepiness causing overactivity has sometimes led to a diagnosis of attention deficit hyperactivity disorder inappropriately treated, as a result, with stimulant drugs instead of treatment for the sleep disorder.21
The features of many individual sleep disorders are open to misinterpretations of a more specific nature. The following are examples of this, roughly in order of how often they occur in the general population. Details of sleep and its disorders, including treatment, are available elsewhere for professionals22,23 or for patients and the general public.24
Abnormalities of the circadian sleep–wake cycle30 provide further examples of the risk of misinterpretation.
As it is not generally realised how complicated behaviour can be during sleep, certain parasomnias are likely to be misinterpreted as other conditions.
The following conditions illustrate how, as mentioned earlier, the true nature of sleep disorders characterised by excessive daytime sleepiness may well be misconstrued.
A number of other sleep disorders, although individually not particularly common, are also at risk of not being correctly recognised, with potentially serious consequences.
It is important to acknowledge that a patient may have a combination of sleep disorder and other conditions of a different nature (and, indeed, more than one type of sleep disorder), especially in the elderly. Therefore, it is all the more important that each complaint and its cause, including the possibility of sleep disorder, are assessed thoroughly. Without this, there is a serious risk that the wrong conclusion will be reached, perhaps causing unnecessary concern but also denying the patient the correct treatment for the sleep disorder which, if properly implemented, is likely to be effective.
The following outline illustrates the main clinical enquiries that should supplement usual history taking schedules. A more detailed account is provided elsewhere45; a modified approach is required in the case of children and adolescents.46
Three basic screening questions for any patient are
The patient's bed partner or other relative should also be questioned.
Positive answers call for a detailed sleep history, essential elements of which are:
A screening questionnaire for use with adults48 or younger patients49 can be a useful starting point in assessment. A structured sleep diary, recording day and night events over 1–2 weeks, may also reveal further valuable information. Other potentially relevant details may be contained in the patient's medical, psychiatric and social histories, including occupational factors and also habits (such as caffeine, alcohol or nicotine consumption and use of illicit drugs) which might affect sleep. A family history of sleep disorders might also be revealing.
These enquiries should be accompanied by a review of systems, as well as physical and mental state examination. It is important to identify any neurological, general medical or psychiatric disorder likely to affect sleep, or physical anomalies of possible importance such as those which predispose to OSA, especially obesity and nasopharyngeal abnormalities.
Clinical information from these sources may well be sufficient to at least provisionally formulate the problem correctly. In a proportion of cases, special investigations will be required, or referral to a sleep disorders service.
DSPS - delayed sleep phase syndrome
NFLE - nocturnal frontal lobe epilepsy
OSA - obstructive sleep apnoea
RBD - rapid eye movement sleep behaviour disorder
REM - rapid eye movement
Competing interests: None.