Misdiagnosing sleep disorders as primary psychiatric conditions

Abstract

Sleep disorders are relevant to psychiatric practice in a number of ways, including the possibility that they may be misdiagnosed as fundamentally psychiatric conditions in patients of all ages. This risk exists in a wide range of collectively very common sleep disorders which need to be considered in explaining insomnia, excessive sleepiness or disturbed episodes of behaviour associated with sleep (parasomnias). Examples given include circadian sleep–wake cycle disorders (such as the delayed sleep phase syndrome), obstructive sleep apnoea, narcolepsy, Kleine–Levin syndrome, sleep paralysis and rapid eye movement (REM)  sleep behaviour disorder. Failure to recognise and treat such disorders is likely to cause and perpetuate psychological problems. Correct recognition requires familiarity with the range and manifestations of sleep disorders.

Box 1

Specific sleep disorders at risk of misdiagnosis as primary sleep disorders

Delayed sleep phase syndrome

Other circadian-rhythm sleep disorders:

• advanced sleep phase syndrome

• jet lag

• night shift work

• irregular sleep–wake schedule

• non-24-hours sleep–wake syndrome

Obstructive sleep apnoea syndrome

Narcolepsy

Other causes of pathological sleepiness:

• • idiopathic hypersomnia

  • Kleine–Levin syndrome

  • Isolated sleep paralysis
  • REM sleep behaviour disorder

Other sleep disorders associated with abnormal behaviour

• hypnagogic/hypnopompic hallucinations

• hypnic jerks

• sensory sleep starts

• restless legs syndrome

• sleepwalking/sleep terrors

• overlap parasomnia disorder

• sleep-related eating disorders

• nocturnal frontal lobe epilepsy

Delayed sleep phase syndrome (DSPS) is the most common of the circadian-rhythm sleep disorders (Wagner, 1990), which are important causes of insomnia and excessive daytime sleepiness. These disorders arise either from malfunction of the endogenous system which regulates the sleep–wake rhythm (the ‘biological clock’, located in the suprachiasmatic nucleus  the hypothalamus) or from environmental effects on these systems (e.g. in jet lag or shift work). Because they are basically biological in nature, this group of sleep disorders requires treatment to produce physiological readjustment of the basic                     sleep–wake mechanism (e.g. by means of chronotherapy schedules, bright light therapy or melatonin). Dagan (2002) has reviewed the evidence that psychiatric disturbance (notably personality disorders and depression) is commonly found in  adults with circadian-rhythm sleep disorders and that certain psychotropic drugs (haloperidol and fluvoxamine) can disrupt sleep–wake cycle mechanisms.

Delayed sleep phase syndrome is thought to occur at all ages but especially in adolescence. For a variety of reasons (e.g. bedtime struggles of young children with parents; late-night social activities in adolescents, often involving consumption  of sleep-disrupting substances such as caffeine, alcohol or nicotine; entertainment at home into the early hours; or working late, in the case of adults) a pattern is established of not going to sleep until very late. This results in the biological  clock resetting itself and a delay of the sleep phase. Consequently, it becomes physiologically impossible to go to sleep  earlier, no matter how motivated a person is to do so. After only a few hours of sound sleep, getting up for school or work is very difficult because sleep requirements have not been met, and fatigue, tiredness and the other consequences of being  sleepy (irritability and poor concentration, for example) are experienced during the day. Sleeping in very late when able to, especially at weekends (which is characteristic of the condition) maintains the sleep delay.

The basic biological nature of DSPS is easily overlooked. Going to sleep late and having difficulty waking in the morning  may well be misconstrued as difficult ‘adolescent’ behaviour or some other form of psychological shortcoming but entreaties to change have no effect. Persistence of the condition readily gives rise to psychological complications, including depression, which are described in a high proportion of people with DSPS (Regenstein & Monk, 1995). The situation can be further complicated if alcohol or other substances are used either to get to sleep at night or to  keep awake during the day.

Because DSPS does not seem to be well-known to professionals (or indeed the public), it is likely to be misinterpreted and attention paid to resulting complications of the condition rather than the true origins of the disturbed mood or behaviour. As in the other sleep disorders discussed here, recognition and appropriate treatment rest on awareness that DSPS exists and on familiarity with its characteristic features. Treatment can be difficult if the patient is motivated to maintain the abnormal                     sleep pattern, e.g. as part of school refusal. In such circumstances, wider psychiatric intervention is required.

Other circadian-rhythm sleep disorders

Obstructive sleep apnoea syndrome

This common and often serious condition occurs in people of all ages (Ohayon et al, 1997). At least 4% of middle-aged males, 2% of adult females and 1% of children may be affected to some degree but only a small minority seek medical advice. These rates are significantly exceeded in certain groups, including obese people, the elderly,  those with hypertension and some forms of learning disability such as Down’s syndrome.

The phrase ‘obstructive sleep apnoea syndrome’ implies repeated interruption of airflow through the upper airway during sleep, in spite of respiratory effort, because of obstruction of the airway. Each interruption is followed by arousal from sleep, which has adverse physical and psychological effects. The main sign of the condition is chronic noisy breathing during sleep,  including snoring, associated with apnoeic episodes. In children, compromised respiration and its consequences can occur without apnoeas because the obstruction is usually partial rather than complete. The main risk factor in adults is obesity. In contrast,  most childhood cases are caused by enlarged tonsils or adenoids. Although snoring is a feature of the syndrome, many people snore without having the condition. However, if noisy breathing during sleep is combined with daytime sleepiness or underperformance,  the possibility of obstructive sleep apnoea syndrome should be considered. Treatment is usually effective in improving sleep and daytime functioning.

The consequences of obstructive sleep apnoea syndrome can be severe, including cardiovascular disease. Similarly, effects on psychological function during the day can be disabling because the repeated interruptions to overnight sleep, which can occur hundreds of times each night, impair its restorative function. The constant nocturnal oxygen desaturations are likely to add to this effect. Daytime sleepiness (including actually falling asleep) is the main feature in adults but, paradoxically, the opposite effect (i.e. overactivity) is reported in children. The sleepiness contributes to a higher risk of car and other accidents and underperformance at work. Children’s performance at school may well suffer. Impairments of memory, attention (especially vigilance) and other cognitive deficits have been described (Engelman et al, 2002). The degree of cognitive impairment can be extreme and misinterpreted as a dementing illness of the more usual type. Other psychiatric effects that have been reported are depression, confusional states and psychotic disorders. Various parasomnias can occur, including sudden distressing awakenings at the end of an obstructive event, and these become an additional source of concern. The poor quality of life imposed by obstructive sleep apnoea syndrome, with restrictions on family and social relationships, adds to the direct psychological complications of the condition.

There is a serious risk of misinterpreting these various neuropsychiatric consequences of the syndrome if the presence of  the underlying sleep-related breathing disorder is not realised. For example, depression appears to be one of the conditions for which patients may well be treated before their obstructive sleep apnoea syndrome is correctly diagnosed (Smith et al, 2002). Perhaps particularly in the elderly, failure to recognise the syndrome may lead to missed opportunities to successfully  treat intellectual decline (Bliwise, 1996).

Narcolepsy

This neurological condition (mainly an abnormality of REM sleep) is not the rarity sometimes supposed (Thorpy, 2001). It occurs in 2–5 per 10 000 of the population (a similar level to Parkinson’s disease or multiple sclerosis) and begins in childhood or adolescence in 30% or more of cases. The classic tetrad of the full narcolepsy syndrome consists of sleep  attacks, cataplexy, hypnagogic hallucinations and sleep paralysis. According to most authorities, diagnosis, particularly  in adults, requires a combination of sleep attacks and cataplexy. The other ancillary complaints may or may not develop. All four symptoms occur in less than 50% of cases. Additional symptoms include persistent tiredness because of disrupted overnight sleep, poor memory and concentration and automatic behaviour (the result of sleepiness). Associations between narcolepsy and  sleep apnoea and also REM sleep behaviour disorder (see below) are not well understood.

There have been consistent reports that many years often elapse before narcolepsy is recognised and, indeed, it seems likely that many cases are never correctly diagnosed. As each of the features mentioned above is open to misinterpretation, it is not surprising that narcolepsy is initially diagnosed as various other conditions, including neurosis, depression and personality disorder (Kryger et al, 2002). In this study, psychiatrists had made the correct diagnosis in only 11% of cases they had seen; the figure for paediatricians was 0%.

The excessive sleepiness in narcolepsy (and, indeed, other pathologically sleepy conditions) can easily be misconstrued by  others (and sometimes patients themselves) as laziness, boredom or depression. The sleep attacks are sometimes considered to be attention-seeking or opting-out behaviour. Cataplexy, which can occur in various forms, including episodes of localised  weakness, clumsiness or merely the feeling of weakness, may be viewed as silly behaviour or even conversion disorder (Dahl, 1996). It has been reported that some cases of schizophrenia have been found to be unrecognised narcolepsy (Douglass et al, 1991).

Clinical presentations of narcolepsy can be dominated by the patient’s emotional reactions to the disorder rather than its diagnostic features, especially if these are denied or concealed because of worry or embarrassment (Stores, 1999). The adverse educational, domestic, occupational and social consequences of narcolepsy (Bruck, 2001) may also serve to deflect attention from the basic condition, with patients being referred to psychiatric or, in the case of children, educational services without the cause of the problems being realised.

Other primary sleep disorders characterised by pathological sleepiness

There are other sleep disorders characterised mainly by excessive sleepiness. Idiopathic (central nervous system) hypersomnia and Kleine–Levin syndrome have the same central feature but with other associated clinical manifestations that tend to misleadingly suggest a psychiatric disorder.

Isolated sleep paralysis

Hypnagogic (falling asleep) and hypnopompic (waking) hallucinations, and also sleep paralysis, appear to be experienced as isolated phenomena by a large proportion of the general population. Although common, their occurrence often does not come to light (even though they can be alarming) because the experiences are concealed out of embarrassment or confusion about  their significance.

Sleep paralysis (Lindsley, 1992) is characterised by recurrent episodes in which ability to perform voluntary movements is lost for short periods on going  to sleep or on awakening. During these episodes, communication is not possible although eye and respiratory movements remain intact and consciousness is clear. The episodes end spontaneously or with external stimulation. The condition is thought to  occur occasionally in 50% or more of the population and chronically in 3–6%. Onset is often in adolescence or early adult   life. Predisposing factors include sleep disturbance and stress. The natural history is ill-defined. Serotonergic medication seems the most effective form of treatment, if required.

The paralysis may be accompanied by dramatic phenomena which are easily mistaken for a psychiatric disorder, especially as  the condition is not well represented in the literature (Stores, 1998). These phenomena include simple or complex visual, auditory and somatic hallucinations (of a hypnagogic or hypnopompic type) which may lead the patient to believe that he or she is being harmed or attacked. The fear or terror engendered can be intensified by a feeling of suffocation and by a sensation of an alien presence. These universally consistent features have often been incorporated into folklore, the episodes variously being interpreted as some form of supernatural event, according to the culture.

Clearly, with these dramatic hallucinatory accompaniments and understandable anxiety on the sufferer’s part, it is important to recognise sleep paralysis as a sleep disorder and not a schizophrenic or other form of psychiatric illness.

REM sleep behaviour disorder

This condition has been described relatively recently (Schenck & Mahowald, 2002). It is of particular psychiatric interest and forensic importance. It was initially thought to be the preserve of elderly males but is now known to occur in both genders and in patients of all ages, including children. It is characterised by a pathological preservation of muscle tone in REM sleep which allows dreams to be acted out. If the dreams are violent, the patient punches, kicks, leaps or runs about. This often causes self-injury or injury to others, especially bed-partners, who may be at serious risk of harm.

Elderly males still form the majority of patients diagnosed with this condition, although women can also be affected. However,                     women may not come to medical attention so readily as men do, because their attacks are less aggressive. There is a strong association with neurodegenerative disorders, especially Parkinson’s disease and Lewy body dementia, and also with narcolepsy. Often, a prodromal period is described (perhaps extending over many years) with persistent sleep-talking, loud vocalisations,   limb twitching or gross limb and body jerking. An acute form of REM sleep behaviour disorder has been reported in association with the use of or withdrawal from alcohol or antidepressant drugs, and misuse of cocaine, amphetamines and other substances.

Because of the various links with organic factors, the condition is increasingly viewed more appropriately as a secondary                     parasomnia rather than the primary sleep disorder once supposed in many cases. Diagnosis rests on eliciting the typical history and demonstrating polysomnographically the REM sleep abnormalities associated with the disturbed behaviour. Clonazepam is a very effective treatment, even in the presence of neurological disease.

Other sleep disorders associated with abnormal behaviour

There are other parasomnias associated with disturbed behaviours, sometimes to a dramatic extent (Stores, 2001), either as part of the parasomnia itself or as a reaction to experiencing it. This applies to both primary parasomnias (i.e. those that are primary sleep phenomena) and secondary parasomnias (manifestations of medical or psychiatric disorders). Again, awareness of these conditions is important in order to avoid failure to recognise their sleep-related nature. Some have medico-legal significance.

Parasomnias can occur at various stages of sleep. Some of those occurring in the pre-sleep period can be distressing or alarming to the extent that the person may dread going to bed in anticipation of experiencing the upsetting episodes.

Conclusions

Sleep disturbance is intimately linked with both child and adult psychiatric disorders in a number of ways. Of basic clinical  importance is the fact that many specific sleep disorders are at risk of being misconstrued as primarily psychiatric conditions and, as a consequence, treated inappropriately.

More detailed enquiries about sleep than are usual in traditional history-taking would be a first step in helping psychiatrists to recognise sleep disorder in patients and identify its nature. Basic screening questions that should be asked routinely of patients and observers are whether the patient has difficulty getting to sleep or staying asleep, whether excessive sleepiness   is a problem during the day and whether the patient has any disturbing episodes at night. A positive answer to any of these questions calls for a detailed sleep history (Aldrich & Naylor, 2000). A sleep–wake questionnaire can also be a useful part of clinical enquiry (e.g. Roth et al, 2002). By means of detailed information collected in these ways, together with an overall review of the patient’s past history  and his or her physical and psychiatric condition, it should be possible to identify, at least provisionally, the nature of any sleep disorder present, provided that the clinician understands the range of disorders described in modern sleep disorders  medicine and their main features. Depending on these preliminary findings, further special investigations, including psychological sleep studies, might be appropriate, with the advice of a sleep disorders specialist in selected cases.

It is essential that sleep disorders do not continue to be overlooked or misinterpreted, not only in psychiatry but in other medical specialities concerned with the care of patients of all ages. Inevitably, the consequences of not recognising the patient’s basic condition and failing to provide appropriate treatment has serious consequences for patients and their families.