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Medical comorbidity of sleep disordersDimitris Dikeos and Georgios Georgantopoulos 1st Department of Psychiatry, Athens University Purpose of review Medical School, Athens, Greece Recently published literature indicates that sleep disorders present with medical Correspondence to Dimitris G. Dikeos, MD, Associate comorbidities quite frequently. The coexistence of a sleep disorder with a medical Professor of Psychiatry, 1st Department of Psychiatry, disorder has a substantial impact for both the patient and the health system.
Eginition Hospital, Athens University Medical School,72 Vas Sofias Avenue, Athens 11528, Greece Tel: +30 2107289230; þ30 2107289324; Insomnia and hypersomnia are highly comorbid with medical conditions, such as fax: +302107289324; e-mail: chronic pain and diabetes, as well as with various cardiovascular, respiratory, Current Opinion in Psychiatry 2011, 24:346–354 gastrointestinal, urinary and neurological disorders. Restless legs syndrome andperiodic leg movement syndrome have been associated with iron deficiency, kidneydisease, diabetes, and neurological, autoimmune, cardiovascular and respiratorydisorders. Rapid eye movement behaviour disorder has been described as an earlymanifestation of serious central nervous system diseases; thus, close neurologicalmonitoring of patients referring with this complaint is indicated.
SummaryIdentification and management of any sleep disorder in medical patients is important foroptimizing the course and prognosis. Of equal importance is the search for undetectedmedical disorder in patients presenting with sleep disorders.
Keywordsexcessive daytime sleepiness, hypersomnia, insomnia, periodic leg movements insleep, rapid eye movement behaviour disorder, restless legs syndrome, sleep-relatedlimb movements Curr Opin Psychiatry 24:346–354ß 2011 Wolters Kluwer Health Lippincott Williams & Wilkins tive sleep apnoea), which falls in the field of pulmonary medicine, the remaining seven broad categories consist of Sleep disorders are increasingly met in clinical practice, insomnia; hypersomnia of central origin not due to a having major effects on well being, overall health and circadian rhythm sleep disorder; circadian rhythm sleep safety, and causing significant economic burden at both disorders; parasomnias; sleep-related movement dis- the individual and societal levels Furthermore, sleep orders; isolated symptoms, apparently normal variants, disorders are commonly associated with other major and unresolved issues; and other sleep disorders. All of medical problems such as chronic pain, cardiovascular these disorders and those in their subcategories might be disease, dementias, metabolic disorders, gastrointestinal comorbid with a multitude of medical conditions, the disorders, and so on. Thus, the approach to the patient presentation of which cannot be accomplished within the with sleep complaints should take into consideration limited space of one paper. The aim of the present review medical history, physical findings and a proper evaluation is to present and discuss the most important of these of the patient's physical health. Conversely, sleep dis- comorbidities; thus, the scope of the paper will focus on order symptoms should be sought during any evaluation medical comorbidities of insomnia, sleep-related limb of a patient with a medical condition, as co-existence of movements, that is, restless legs syndrome (RLS) and sleep problems is associated with worse quality of life, periodic leg movement syndrome (PLMS), rapid eye course and prognosis of the medical condition, and movement (REM) sleep behaviour disorder (RBD), increased use of health system facilities and hypersomnias/excessive daytime sleepiness (EDS).
In the International Classification of Sleep Disorders(ICSD-2), eight broad categories of sleep disorders are listed, along with several subcategories under each Insomnia is one of the most frequent conditions around category, as well as additional sleep-related disorders the world It is considered to be the subjective in its Appendices A and B Leaving out the category complaint of compromised sleep quantity and/or quality of sleep-related breathing disorders (including obstruc- and it can be assessed accordingly It can be either 0951-7367 ß 2011 Wolters Kluwer Health Lippincott Williams & Wilkins Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Medical comorbidity of sleep disorders Dikeos and Georgantopoulos primary or comorbid with mental or somatic disorders in the case of somatic comorbidities, the medical con-
The comorbidity of sleep disorders and various dition may be the result of, a contributing factor to, or a medical conditions is quite frequent and its pre- separate entity from insomnia The prevalence and sence has a substantial negative impact on patient consequences of insomnia have significant implications overall status and the health system resources.
for both the patient and public health. Various studies
Chronic pain and diabetes, as well as various car- have shown that people with chronic insomnia use sig- diovascular, respiratory, gastrointestinal, urinary nificantly more medical services than those without and neurological disorders, coexist frequently with insomnia and have significantly higher risks for falls and automobile and industrial accidents, make signifi-
Iron deficiency, kidney disease and neuropathic cantly more errors at work, exhibit less productivity and conditions mainly due to diabetes, neurological or miss twice as many workdays as those without insomnia autoimmune disorders are the main factors behind restless legs syndrome and periodic leg movementsyndrome.
A multitude of medical conditions are associated with
Rapid eye movement behaviour disorder may be a insomnia: chronic pain associated or not with skeletomus- side-effect of antidepressant treatment and it is also cular disorders and/or cancer; diabetes and cardiovascular frequently an early manifestation of neurodegen- disorders; as well as various respiratory, gastrointestinal, erative disorders such as Parkinson's disease, urinary, neurological and menopausal disorders. It also dementia with Lewy bodies, Alzheimer's disease seems that presence of any chronic disease and number and multiple system atrophy, its presence preced- of hospitalizations in the previous year are significantly ing by many years the appearance of their respect- associated with insomnia .
ive characteristic symptoms.

Hypersomnia may be comorbid with the same Insomnia in chronic pain and associated conditions medical conditions as insomnia, but its presence Among insomniac individuals, chronic pain is much more is also associated with higher general mortality.
frequent than among noninsomniac individuals (50 vs.
18%) 25–40% of patients with various chronic painconditions complained of insomnia vs. 13% of the general 10% of those without insomnia, whereas 44% of hyper- population whereas insomnia was found to be 4.3 tensive patients reported insomnia vs. 19% of individuals times more frequent among chronic pain patients in the without hypertension In the large cross-sectional Ibadan study of ageing on 2152 participants ; chronic Norwegian study, however, the prevalence of insomnia pain was mainly due to arthritis (predominantly rheuma- among hypertensive patients was greater than that of the toid), spinal pain and fibromyalgia In a large general population, but the difference was by far less cross-sectional study on 47 700 participants in Norway pronounced (15 vs. 13%, respectively) Myocardial assessing comorbidity of insomnia, mental conditions and infarction and congestive heart failure patients were more chronic pain were the only correlates of insomnia that likely than individuals with mild hypertension to suffer remained strongly significant after adjustment for other from mild insomnia [respective odds ratios (ORs) were confounders The prevalence of insomnia among 1.9 and 1.6]; for congestive heart failure, the OR for cancer patients is about double that of the general popu- severe insomnia was 2.5 Particularly for acute myo- lation, this association considered to be due to cancer cardial infarction, sleep disturbance is a frequent com- itself, various symptoms of pain and discomfort or various plaint in the initial period, but it seems to subside over a treatment complications; it has been suggested that research on the circadian timing of treatments may pro-vide results that could help reduce sleep disorders in Insomnia in conditions associated with other systems cancer patients undergoing therapy A great proportion (60%) of patients with breathingproblems complain of chronic insomnia (vs. 21% in a Insomnia in diabetes and cardiovascular disorders control sample), whereas 25% of individuals with insom- Diabetes mellitus is another condition that is associated nia report breathing problems (vs. 6% in individuals with insomnia, although this association is relatively weak without insomnia) More than half of all patients In a recent study, however, it was found that short with chronic obstructive pulmonary disease (COPD) sleep duration is a clinically significant risk factor for complain of difficulties in initiating or maintaining sleep type-2 diabetes . Impaired glucose tolerance is also and 25% present with excessive daytime sleepiness , associated with short sleep in individuals with or without and asthmatic patients were found to have an OR for diabetes . In one cross-sectional retrospective study insomnia of 1.4 compared with the general population based on a mailed questionnaire, presence of heart dis- Similarly, individuals with insomnia report a higher pro- ease was reported by 22% of individuals with insomnia vs.
portion of gastrointestinal problems vs. controls (34 vs.
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Medical comorbidity 9%) and 55% of patients with disorders of the gastroin- Health Professional follow-up study on 23 119 men after testinal tract (especially gastroesophageal reflux excluding those suffering from diabetes and arthritis.
complain of insomnia (vs. 20% of the control sample) The prevalence of Parkinson's disease was found to be . Sleep problems are also particularly common among about double among sufferers with RLS compared with end-stage renal disease (ESRD) patients undergoing nonsufferers Inversely, RLS was found to have 3% dialysis, among whom the prevalence of insomnia is prevalence among 200 Parkinson's disease patients, vs.
between about 60 and 85% female sex, 0.5% among normal controls In a controlled study, afternoon haemodialysis, other sleep disorders (RLS, the prevalence of RLS among 76 patients with amyo- obstructive sleep apnoea) and depression seem to be trophic lateral sclerosis (ALS) was found to be 25% independent predictors of insomnia among ESRD compared with 8% among 100 controls patients Self-reported insomnia and reducedsleep quality are, in addition, very frequent among Restless legs syndrome in cardiovascular disease and patients with nocturia of any cause . Various neuro- logic diseases are associated with insomnia ; 50% of In a population-based cross-sectional study examining Parkinson's disease patients have insomnia, which seems the prevalence of cardiovascular risk factors in partici- to wax and wane over time and 30–70% of trau- pants with and without RLS (N ¼ 1537), blood tests of matic brain injury (TBI) patients report insomnia symp- RLS participants showed significantly higher fasting toms Finally, in women, insomnia is associated with blood glucose level, higher prevalence of hypercholes- menopause and with the severity of the vasomotor symp- terolaemia, reduced renal function and increased preva- toms that accompany it lence of low haematocrit. Participants with RLS had ahigher BMI, larger hip circumference and were less fit. Itwas found that female sex and the high-density lipopro- Sleep-related limb movements tein (HDL)/low-density lipoprotein (LDL) cholesterol The most important sleep-related limb movements are ratio were significantly associated with RLS RLS and PLMS.
An association of RLS with obesity has been found in a General remarks on restless legs syndrome recent study on a sample of about 90 000 individuals RLS is a disorder characterized by an urge to move the assessed by mailed interviews. It was found that 6.4% extremities, frequently associated with paraesthesia or of women and 4.1% of men had RLS and the prevalence dysaesthesia; temporary relief of the urge with move- increased progressively with increasing BMI and waist ment; and onset or worsening of the symptoms at rest, circumference. This association was independent of age, inactivity or at night . RLS has a prevalence of about smoking status, anxiety score, use of antidepressants and 3–15% in the general population and it has a presence of a number of chronic diseases. A similar negative impact on physical functioning, bodily pain, association was found between obesity in early adulthood general health and vitality .
(age 18–21) and RLS prevalence in mid-life or later (age40 years and higher), suggesting that obesity is a risk Iron deficiency/kidney disease and restless legs factor for the development of RLS syndromeA well established association is that of RLS with iron RLS is strongly related to coronary artery disease (OR deficiency; it has been observed in cases of malignancies, 2.2) and any cardiovascular disease (including coronary various iron-deficiency anaemias, regular blood donors, artery disease, heart failure or stroke) findings on pregnancy and many other conditions characterized by hypertension are still controversial although low iron stores In many cases, RLS appears there seems to exist a possible relationship between even with subclinical iron deficiency (as revealed by mean blood pressure and RLS or PLMS symptoms reduced ferritin levels) while levels of haemoglobin It has been argued that the sympathetic hyperac- tivity associated with RLS/PLMS leads to heart diseaseand stroke via hypertension and/or via atherosclerotic An association of RLS with kidney disease/uraemia has plaque formation and rupture; alternatively, comorbid- been found, which is usually inverted after kidney trans- ities associated with RLS/PLMS, such as renal failure, plantation; iron deficiency might be a contributing factor diabetes, iron deficiency and insomnia, may predispose to to this association, but it does not seem to be the only one heart disease and stroke In a controlled study on 124 diabetes mellitus patients vs.
Restless legs syndrome in neurological disorders 87 controls with other endocrine disorders, the preva- The comorbidity of RLS with Parkinson's disease was lence of RLS was higher among the diabetes mellitus examined in a large cohort of men participating in the group by a factor of about 3 (17.7 vs. 5.5) In another Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Medical comorbidity of sleep disorders Dikeos and Georgantopoulos study on 121 type 2 diabetes patients, for whom it was not . The prevalence of PLMS in the general population mentioned whether they suffered from polyneuropathy is estimated to be 4–11% or not, it was found that 45% of them were suffering fromsecondary RLS This association was found also in Periodic leg movement syndrome in other sleep prediabetic patients with normal fasting glucose and abnormal glucose tolerance test other studies PLMS is a frequent finding in various sleep disorders have suggested that RLS in diabetes mellitus is a result such as obstructive sleep apnoea syndrome (OSAS), of diabetic polyneuropathy and that it may narcolepsy and RBD; the prevalence of PLMS in OSAS respond better to neuropathic pain medications rather is 24%, decreasing with continuous positive airway pres- than dopaminergic drugs Polyneuropathy, however, sure (C-PAP) treatment, whereas up to 70% of RBD does not seem to fully explain the presence of RLS in patients have a PLMI of 10 or higher diabetes mellitus patients Presence of RLSamong diabetic patients has a significant impact on Periodic leg movement syndrome in medical conditions patients' quality of sleep PLMs are also a frequent finding in RLS and bothconditions share common somatic comorbidities. Similar Restless legs syndrome in other disorders to RLS, PLMS is found to be more frequent among RLS has also been found to be associated with a variety individuals with uraemia (20–45%) and/or ESRD, of rheumatological and immunological conditions, show- Parkinson's disease (in which the PLMI has been ing a prevalence of 20–30% (two to six times that reported up to 68), iron deficiency, severe congestive of the general population) among patients with rheuma- heart failure (52 vs. 11% in controls), juvenile fibromyal- toid arthritis, various other arthropathies, fibromyalgia, gia (38%), scleroderma (48%) and hypertension (mean Sjogren's syndrome and scleroderma Neuropathy prevalence 18%, associated with severity); PLMS' fre- due to rheumatoid arthritis is being suggested as an quency is furthermore elevated in syringomyelia (61%), explanation for the increased prevalence of RLS in this spinal cord injury (mean PLMI 35) and Gille de la condition based on neurophysiological findings but Tourette syndrome (mean PLMI 19, PLMS found in also subclinical iron deficiency due to chronic use of five out of seven patients examined) Finally nonsteroidal anti-inflammatory agents, as well as dopa- PLMs (and, to some extent, RLS symptoms) increase mine transmission abnormalities due to chronic pain, has with various psychoactive drugs, especially antidepress- ants [mainly selective serotonin reuptake inhibitors(SSRIs) and venlafaxine] and lithium Finally, a strong association between respiratory symp-toms, asthma, COPD and RLS was described in a studyon a well defined population (N ¼ 1937) from two Rapid eye movement behaviour disorder countries
The relationship between RLS and RBD is a condition characterized by loss of muscular COPD has also been described before but the atonia and the appearance of motor behaviours (usually pathogenesis is unknown.
violent) during REM sleep (i.e. when dreaming) Theabnormal motor and vocal behaviours during REM sleep General remarks on periodic leg movement syndrome have different degrees of severity across different nights PLMS is a condition characterized by periodic episodes and through a single night, ranging from mild limb of repetitive and highly stereotyped limb movements jerking to jumping out of bed. Typical behaviours that occur during sleep and in wakefulness (particularly include punching, kicking, beating, biting, sitting on during rest). The movements usually occur in the legs the bed, jumping out of bed, whispering, talking, shout- and consist of extension of the big toe in combination ing, swearing, crying, laughing and singing. Patients and with partial flexion of the ankle, knee and sometimes hip.
their bed partners may suffer lacerations, contusions and They may also occur in the upper limbs and can be fractures. Nonviolent behaviours (e.g. gesturing, elabo- unilateral or bilateral rated pseudo-purposeful behaviours, whistling) mayoccasionally coexist with the typical violent behaviour The criteria for the syndrome are polysomnographic and Recalled dreams commonly have a negative first require identification of a PLM . The mean emotional content and include being attacked, robbed number of PLMs per hour of total sleep time is the or chased by people, frightened or attacked by animals PLM index (PLMI). A PLMI of more than 5 is con- and falling off a cliff sidered pathological, although it has also been suggestedthat the cut-off should be put at 10 PLMS is RBD usually develops after the age of 50 and its preva- considered mild for a PLMI up to 25, moderate for lence is estimated to be less than 1% of the general 25–50 and severe for an index 50 or higher or if there population For the diagnosis, the clinical descrip- are more than 25 PLMs per hour associated with arousal tion is needed, corroborated usually by the bed partner; Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Medical comorbidity all-night polysomnography with infrared video monitor- and regional blood flow The conclusions of these ing is performed, mainly for differential diagnosis studies as well as of older similar ones (reviewed in ) RBD is considered to be either idiopathic or secondary are still inconclusive, and, as there are not many publi- to neurological conditions such as Parkinson's disease, cations that have followed those patients with RBD who dementia with Lewy bodies (DLB), multiple system did not develop a neurodegenerative disorder, the matter atrophy (MSA), narcolepsy, and so on is still unresolved Rapid eye movement sleep behaviour disorder inneurological disorders Hypersomnias and Excessive Daytime Compared with the population prevalence of 1%, RBD is found in 15–60% of Parkinson's disease patients (parti- All hypersomnias are characterized by the presence of cularly those having the akinetic/rigid manifestation of EDS, one of the most commonly reported symptoms the disease in 50–83% of patients with DLB and in concerning sleep. The diminished alertness, attention 90–100% of patients with MSA . As all three of the and concentration that accompany EDS increase signifi- above are synucleinopathies, it is considered that alpha cantly the risk of occupational and motor vehicle acci- synuclein pathology is a causative factor of RBD, at least dents Validated questionnaires as the Epworth in the majority of cases. On the other hand, RBD preva- Sleepiness Scale (ESS) and the Stanford Sleepiness Scale lence is also found to be high in narcolepsy and elevated (SSS) are used in order to assess EDS, whereas laboratory (though to a lesser degree) in other neurological disorders evaluation of sleep by methods such as all-night Poly- such as spinocerebellar ataxias, Huntington's disease, somnography (PSG), Multiple Sleep Latency Test ALS, Guillain-Barre´, multiple sclerosis, epilepsy, autism, (MSLT) or Maintenance of Wakefulness Test (MWT) Tourette syndrome, Alzheimer's disease, inflammatory is used to objectively evaluate reduced alertness and encephalitis, stroke, TBI, brain stem tumours and so on, excessive sleepiness, and to assist in the identification which are unrelated to synuclein disturbance of their cause(s) RBD can also be triggered by the administration ofcertain drugs, especially antidepressants belonging to EDS can be a result of a number of intrinsic or extrinsic the serotonin-uptake inhibitors conditions It can be due to one of the primaryhypersomnias [narcolepsy, idiopathic hypersomnia and Rapid eye movement sleep behaviour disorder as a recurrent hypersomnia (Kleine–Levin syndrome)]; insuf- precursor of neurodegenerative disorders ficient sleep time due to lifestyle and sleep habits, shift Clinically, the most important aspect is that the appear- work, circadian rhythm disorders or other conditions ance of RBD, in the absence of an apparent neurological characterized by reduced night-sleep (such as fragmen- condition or administration of drugs that may account for ted sleep, sleep apnoea, RLS or PLMS); and secondary to its presence, seems to be a preclinical marker for the psychiatric disorders, medications (benzodiazepines, development of a neurodegenerative disease, usually antidepressants, antipsychotics, antihistamines, opioids, Parkinson's disease or DLB In a recent follow- beta-blockers, etc.) and certain medical conditions up study of 93 patients who had been diagnosed with idiopathic RBD and were examined for a period up to12 years (mean 5.2 years), it was estimated that the risk for the development of a neurodegenerative disease Narcolepsy is the main idiopathic condition causing (Parkinson's disease, DLB, Alzheimer's disease and EDS. It can be primary (associated with the HLA MSA) was 17.7% in 5 years, 40.6% in 10 years and DQB10602 allele) or secondary resulting from neuro- 52.4% in 12 years Cumulative incidence of neuro- logical disorders and other conditions affecting the cen- degenerative disorders in various longitudinal studies tral nervous system (CNS), such as brain tumours (especi- following patients with RBD was 16–65% for Parkinson's ally diencephalic and midbrain ones), stroke, multiple disease, 8–15% for DLB, 4% for Alzheimer's disease and sclerosis, cerebral trauma or encephalitis Furthermore, the risk of narcolepsy in the presence ofa history of streptococcal throat infection before the age In recent years, several studies have been conducted in of 21 years was estimated to be 5.4 times higher, the attempt to identify indices of the probability of suggesting that rheumatic fever might induce narcolepsy, transition of RBD to a neurodegenerative disorder; auto- probably in a similar manner as it does Syndenham's nomic dysfunction due to adrenergic neuron dysfunction chorea The risk for narcolepsy was also found to is assessed by iodine-131-meta-iodobenzylguanidine be increased (OR ¼ 5.1) for individuals who had lived (I-MIBG) cardiac scintigraphy or R-R variability with two or more household smokers (a factor known to , and midbrain structures are assessed by sonography aggravate strep-throat infections) before age 21; the find- MRI diffusion tensor imaging (DTI) ing was more pronounced among genetically susceptible Copyright Lippincott Williams & Wilkins. 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Medical comorbidity of sleep disorders Dikeos and Georgantopoulos individuals bearing the HLA narcolepsy-associated hap- from hypersomnolence; concomitant presence of dia- betes, cardiovascular disease or depression is associatedwith persistence of daytime sleepiness even after the Hypersomnia in other neurological disorders successful treatment of sleep apnoeas by C-PAP In EDS seems to be quite prominent among Parkinson's a study evaluating the sleep/wake cycle of individuals disease patients, with a frequency ranging from 8% to with asthma, it was concluded that asthma, as a chronic more than 50% in various studies . Consider- inflammatory disease, can affect daytime wakefulness ing the association of EDS with Parkinson's disease, it has furthermore, data on 470 asthmatic patients indi- been suggested that the reason behind the EDS might be cated that women were much more likely to exhibit EDS the neurodegenerative mechanism itself (including dopa- than men EDS in renal dialysis patients has been mine pathways and other neurochemical components of shown to be correlated with higher blood urea nitrogen the ascending reticular activation system) and/or the (BUN), high frequency of PLM and sleep apnoea various drugs used . Indeed, a multicentre control Other medical disorders associated with EDS study on Japanese patients provided data suggesting that are rheumatological, respiratory, cardiovascular, urinary sleepiness in Parkinson's disease is dependent on the (such as lower urinary tract symptoms or any other disease itself and on the dopaminergic treatment rather disorders associated with nocturia), malignancy and gen- than nocturnal disturbances EDS, in addition, was found to be a predictor for the development of Parkin-son's disease in a large cohort of more than 3000 older In a study examining the relationship of EDS with men followed for 7 years In another study among common medical disorders in an unselected com- munity-based sample, the authors assessed responses examined in the sleep laboratory by MSLT, 57% had of 2612 individuals (aged 18–65) after excluding shift an ESS score greater than 10 and 37% had a mean sleep workers and those with suspected sleep disordered latency of less than 5 min during the MSLT; none of breathing or narcolepsy. Participants across a range of these patients exhibited a sleep onset REM episode, medical disorders were evaluated using the ESS and indicating that their hypersomnia was not due to comor- patient reports of nocturnal sleep. Individuals with ulcers [OR ¼ 2.21, 95% confidence interval (CI) ¼ 1.35–3.61]and migraine (OR ¼ 1.36, 95% CI ¼ 1.08–1.72) were In addition to Parkinson's disease, neurological diseases shown to have independently and clinically significantly that are frequently found among patients with EDS higher levels of EDS relative to other common medical (dementias, Huntington's disease, progressive supranuc-lear palsy, multiple sclerosis, spinocerebellar ataxia), Relationship of hypersomnia with general morbidity and stroke, epilepsy, structural brain lesions (TBI or brain tumours, especially diencephalic, midbrain, hypothala- Finally, a relationship seems to exist between EDS and mic, pituitary), infections of the CNS (especially African general morbidity and mortality. In the National Health trypanosomiasis and encephalitis lethargica) and neuro- Interview Survey 2005, a cross-sectional study of 30 397 muscular diseases (including myasthenia gravis, poly- participants, it was demonstrated that there is a positive neuropathies, poliomyelitis, etc.) association between daily sleep being longer than 9 h andcardiovascular disease, compared with sleep duration of Hypersomnia in other medical disorders 7 h per day (OR ¼ 1.57, 95% CI ¼ 1.31–1.89) Regarding the comorbidity of EDS with nonneurological Similarly, in a cohort study on 98 634 participants in medical disorders, in a study of consecutively recruited Japan (the Japan Collaborative Cohort study), it was adult type 2 diabetic patients, the proportion of diabetic concluded that long sleep duration (>10 h) was associated patients with elevated ESSs (> or ¼12) was higher than with 1.5 to two-fold increase of mortality from stroke, that of the controls (15.5 vs. 2.1%, P ¼ 0.02) A total cardiovascular disease and other causes of death secondary analysis on individuals drawn from the except cancer, suggesting that, although mechanisms are National Sleep Foundation's Sleep and Aging poll indi- not clear, long sleep duration may be an early symptom of cated that sleep disturbances affect not only sleep quality various disorders with high mortality rates but also daytime function in older adults with diabetesin another study, although the association betweenglycated haemoglobin (HbA1c) values and ESS score has been found to be significant, the causality of the effect The sleep disorders whose comorbidities are reviewed in was considered to be uncertain, as hypersomnolence in the present paper are insomnia, the sleep-related limb diabetic patients may be mediated by RLS, nocturia or movements RLS and PLMS, RBD and hypersomnia.
snoring/OSAS . OSAS patients suffer frequently Medical comorbidities are quite frequent among all these Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
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