Higher Epworth Sleepiness Scale Research Articles

Psychometric evaluation of a Swedish version of the Functional Outcomes of Sleep Questionnaire, FOSQ

Objective. The Functional Outcomes of Sleep Questionnaire, FOSQ, is a self-administered 30 item questionnaire, designed to assess the impact of disorders of excessive sleepiness on activities of daily living. The aim was to evaluate the psychometric properties of a Swedish translation of the English original. Materials and methods. A Swedish version of the FOSQ was answered by 75 consecutive patients, diagnosed with obstructive sleep apnea syndrome and in need of treatment. The Short Form Health Survey (SF-36) and Epworth Sleepiness Scale (ESS) were also answered at the same time to evaluate validity. The first 25 patients answered the FOSQ a second time, 3 weeks later, to assess reliability. Results. The test–re-test reliability and intra-class correlation of the different sub-scales in the FOSQ varied between 0.71–0.92 and was 0.92 for the total scale, all statistically significant. Cronbach's alpha, calculated as a measure of internal consistency, varied between 0.84–0.92 for FOSQ sub-scales and was 0.96 for the total score. Statistically significant correlations between FOSQ sub-scales and the eight sub-scales in the SF-36 supported the validity. Discriminant validity, calculated by splitting responders with high and low ESS scores, revealed that FOSQs scores differed significantly between the groups. Conclusions. The results suggest that the Swedish version of the FOSQ has psychometric qualities in line with the original. It might, therefore, be a potentially useful, reliable and valid instrument for clinicians and researchers when measuring variables related to quality-of-life in sleep disorders in this language area.

Abstract 9689: Endothelial Function & Sleep Quality

Background: Sleep apnea is associated with cardiovascular disease (CVD). Although obstructive sleep apnea is also associated with abnormal endothelial function (EF), a precursor of CVD, it is unknown whether milder sleep disturbance affects EF. We investigated the relationship between sleep quality and EF, with the hypothesis that poor sleep quality, in the absence of sleep apnea, will be associated with endothelial dysfunction. Methods: 684 community participants free of CVD, 68% female, aged 37 to 60 years, were enrolled in the Emory-Georgia Tech Predictive Health Institute study. We measured CVD risk factors, sleep quality using the Epworth Sleepiness Scale (ESS) and selected questions from the Pittsburgh Sleep Quality Index (PSQI). EF was measured using brachial artery flow-mediated dilation (FMD). Multivariate analysis of covariance was used to adjust for age, race, gender, smoking, hypertension, diabetes, and body mass index. Results: Lower FMD measurements were correlated with higher ESS scores that reflect poor sleep quality (r = -0.0858, p = 0.03), a difference that remained significant after multivariate adjustment for the aforementioned risk factors (β = -0.0009, p = 0.03). Participants who reported cough or snoring during sleep in their PSQI questionnaire also tended to have lower FMD (6.2±3.4% compared to 6.9±4.3%, p = 0.056), a difference that remained significant after multivariate adjustment for risk factors above (p = 0.03). Conclusion: In a community-based population without clinically diagnosed sleep apnea, we demonstrate a significant association between sleep quality assessed by questionnaires and EF. Poor sleep quality reflected by symptoms of cough / snoring, or a high ESS score, may contribute to CVD and hypertension by adversely affecting EF.

SUBJECTIVE SLEEP QUALITY AND DAYTIME SLEEPINESS IN A LARGE SAMPLE OF PATIENTS WITH CHRONIC FATIGUE SYNDROME (CFS)

Chronic fatigue syndrome (CFS) is characterised by incapacitating fatigue in combination with a number of minor criteria, including unrefreshing sleep without further specifications, in the absence of psychiatric and internal disease. As little data exist on subjective sleep quality and daytime sleepiness, these parameters were assessed in a large sample of CFS patients.Consecutive patients with a diagnosis of CFS in a tertiary referral centre filled out the Fatigue Questionnaire (FQ), Medical Outcomes Study 36-Item Short Form Health Survey (MOS SF-36), Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality Index (PSQI).Inclusion comprised 415 individuals (mean age 40.5 yr, SD 7.9, range 18-64; 86% female). Mean FQ (26.90; SD 4.04), mean Global Physical Health from the MOS SF-36 (29.30; SD 12.25) and Global Mental Health from the MOS SF-36 (49.62; SD 18.31) scores corresponded with literature data for similar CFS samples. High mean ESS (10.51; SD 5.52) and global PSQI (10.17; SD 4.02) were observed. No significant relationship was found between ESS and global PSQI. In contrast, regression analysis demonstrated a significant cubic relation between ESS and ‘PSQI without daytime dysfunction’. A subgroup (n = 69) with an insomnia-like phenotype low ESS (< 5), high PSQI (mean 11.51; SD 3.86) was observed.The assessment of subjective sleep quality and daytime sleepiness in a large sample of CFS patients indicated high mean PSQI and ESS values. ESS and ‘PSQI without daytime dysfunction’ were inversely related at the spectral ends of ESS. A distinct subgroup with clinical features of insomnia was identified.

Prevalence of High Epworth Sleepiness Scale Scores in a Rural Population

Increased daytime sleepiness is an important symptom of obstructive sleep apnea (OSA). OSA is frequently underdiagnosed, and the Epworth Sleepiness Scale (ESS) can be a useful tool in alerting physicians to a potential problem involving OSA. To measure the prevalence and determinants of daytime sleepiness measured using the ESS in a rural community population. A community survey was conducted to examine the risk factors associated with ESS in a rural population in 154 households comprising 283 adults. Questionnaire information was obtained regarding physical factors, social factors, general medical history, family medical history, ESS score, and self-reported height and weight. Multivariable binary logistic regression analysis based on the generalized estimating equations approach to account for clustering within households was used to predict the relationship between a binary ESS score outcome (normal or abnormal) and a set of explanatory variables. The population included 140 men (49.5%) and 143 women (50.5%) with an age range of 18 to 97 years (mean [± SD] 52.0±14.9 years). The data showed that 79.2% of the study participants had an ESS score in the normal range (0 to 10) and 20.8% had an ESS score >10, which is considered to be abnormal or high sleepiness. Multivariable regression analysis revealed that obesity was significantly associated with an abnormal or high sleepiness score on the ESS (OR 3.40 [95% CI 1.31 to 8.80). High levels of sleepiness in this population were common. Obesity was an important risk factor for high ESS score.

The effect of allergic rhinitis on the degree of stress, fatigue and quality of life in OSA patients

Both allergic rhinitis (AR) and obstructive sleep apnea (OSA) are known to increase stress and fatigue, but the result of their coexistence has not been studied. The objective of this study was to evaluate the amount of stress and fatigue when AR is combined with OSA. One hundred and twelve patients diagnosed with OSA by polysomnography were enrolled. Among them, 37 patients were diagnosed with AR by a skin prick test and symptoms (OSA-AR group) and 75 patients were classified into the OSA group since they tested negative for allergies. We evaluated the Epworth sleepiness scale (ESS), stress score, fatigue score, ability to cope with stress, and rhinosinusitis quality of life questionnaire (RQLQ) with questionnaires and statistically compared the scores of both groups. There were no significant differences in BMI and sleep parameters such as LSAT, AHI, and RERA between the two groups. However, the OSA-AR group showed a significantly higher ESS score compared to the OSA group (13.7 ± 4.7 vs. 9.3 ± 4.8). Fatigue scores were also significantly higher in the OSA-AR group than in the OSA group (39.8 ± 11.0 vs. 30.6 ± 5.4). The OSA-AR group had a significantly higher stress score (60.4 ± 18.6 vs. 51.2 ± 10.4). The ability to cope with stress was higher in the OSA group, although this difference was not statistically significant. RQLQ scores were higher in the OSA-AR group (60.2 ± 16.7 compared to 25.1 ± 13.9). In conclusion, management of allergic rhinitis is very important in treating OSA patients in order to eliminate stress and fatigue and to minimize daytime sleepiness and quality of life.

Clinical features of childhood narcolepsy. Can cataplexy be foretold?

Background Narcolepsy is a life-long disease characterized by abnormal regulation of the sleep–wake cycle and increased penetration of rapid eye movement (REM) sleep. In children, narcolepsy without cataplexy is more frequently seen than in adults. The aim of our study was to evaluate clinical and polysomnographic parameters to verify if cataplexy appearing later in life can be foretold. Methods 30 patients (12 boys), who contracted narcolepsy before the age of 18, were enrolled. All underwent clinical examination, nocturnal polysomnography (PSG), multiple sleep latency test (MSLT), HLA-DQB1∗0602 testing and, most of them Epworth Sleepiness Scale (ESS) rating. The Mann–Whitney rank and Fisher’s tests were used for statistical analysis. Results Narcolepsy without cataplexy (NwC) was diagnosed in 40% of the patients. The mean age at the first symptoms was 14.0 ± 3.0, at diagnosis 15.6 ± 3.1 years. Narcolepsy was accompanied by hypnagogic hallucinations in 15 and sleep paralysis in 12 patients. Frequent symptoms were sleep inertia during awakening, REM behavior symptoms, behavioral and serious school problems. BMI was higher in patients with narcolepsy-cataplexy (N-C). A high ESS score was indicative of excessive daytime sleepiness (17.1 ± 2.5). Mean MSLT sleep latency was 4.0 ± 3.1 min with 3.2 ± 1.4 sleep onset REM periods (SOREMs) with no difference between the two study groups. HLA typing revealed no differences either. The N-C group showed a higher degree of wakefulness and superficial non-REM (NREM) stage 1 with a lower NREM stage 3 during PSG. Conclusion Narcolepsy in childhood leaves very little scope for the prediction of cataplexy later in life.

Restless legs syndrome in hemodialysis patients: association with depression and quality of life

The prevalence of restless legs syndrome (RLS) ranging from 6.6% to 83% has been reported in different case series. The pathophysiology of RLS in uremia is still unclear. The aim of this study was to assess the frequency of RLS in the hemodialysis patients and to explore depression and associated detrimental impact on quality of life. The diagnosis of RLS was made using the criteria of the International Restless Legs Study Group. The polyneuropathy was diagnosed according to clinical signs and symptoms. Each subject completed three questionnaires: Beck Depression Inventory, Short Form-36 Quality of Life Scale, and the Epworth Sleepiness Scale (ESS). Biochemical parameters including hemoglobin, serum ferritin, and Kt/V index were collected. The data of the patients with and without RLS or clinical polyneuropathy (PNP) were compared. There were 41 male and 40 female patients. RLS, PNP, and high ESS scores were seen in 12%, 47%, and 7% of hemodialysis patients, respectively. Beck depression inventory scores were high in patients with RLS when compared to those without (28.9 ± 9, p = 0.007). General health score in the RLS patients, physical functioning score in the PNP patients were significantly lower (GH, 20.7; p = 0.036; PF, 10.5; p < 0.005). We did not observe any association between hemoglobin, ferritin levels, and Kt/V index in the RLS patients. However, Kt/V index in the PNP patients were low. The frequency of RLS in hemodialysis patients was lower than that reported from similar studies in other countries. The presence of RLS and PNP in hemodialyzed patients negatively affects quality of life, and RLS contributes to occurrence of depression.

A Survey of Subjective Sleepiness and Consequences in Attending Physicians

This article surveyed attending physicians on their work hours, sleep schedule, daytime sleepiness, and the perceived relation of these factors to patient safety, quality of care, and personal well-being. Physicians answered demographic and workload questions and attitudinal questions regarding work-hour limitations; the Epworth Sleepiness Scale (ESS) was used to measure subjective sleepiness, and an 18-item Impact Questionnaire was also used. Of 180 participants, 41 (23%) attending physicians manifested abnormal ESS scores (11 or greater). Private practice- and surgically-based subspecialties had higher ESS scores. Reduced sleep, but not hours worked, was associated with increased sleepiness. Sleepy physicians were more likely to associate sleep loss with medical errors and driving impairment. Sleepiness may be attenuated by education regarding consequences of insufficient sleep and institution of effective countermeasures.

Effects of 6/6 and 4/8 Watch Systems on Sleepiness among Bridge Officers

During the last ten years, severe sleepiness or falling asleep by watch keeping officers has been a direct or a contributing factor in a number of maritime accidents. This study examined the relationship between two watch systems and its impact on fatigue and sleepiness in bridge officers. A questionnaire and a sleep/work diary were sent to a representative sample of the Finnish Maritime Officer Association. In all, 185 bridge officers answered the questionnaire on sleep, work hours, and safety, including the Skogby Excessive Daytime Sleepiness index (SEDS); 42% of the bridge officers worked two 4 h watches (4/8) per day, while 26% worked two 6 h watches per day (6/6). Ninety‐five of the participants completed a sleep diary for seven consecutive days while at sea. The timing of the watch duties and sleep was recorded, as was subjective sleepiness every 2 h using the Karolinska Sleepiness Scale (KSS). 17.6% of the participants had fallen asleep at least once while on duty during their career. Compared to the 4/8 watch system, the officers working the 6/6 watch system reported shorter sleep durations, more frequent nodding‐off on duty (7.3% vs. 1.5%), and excessive sleepiness (32% vs. 16% with SEDS>14). Based on a logistic regression analysis, high SEDS was significantly related with probable obstructive sleep apnea (OR 5.7), the 6/6 watch system (OR 4.0), and morningness‐eveningness while controlling simultaneously several individual and sleep‐related factors. Subjective sleepiness (KSS) was highest at 04:00 and 06:00 h. In a multivariate analysis, the KSS was significantly related to time of day, time after awaking, sleep length, and interactions of the watch systems with age, morningness‐eveningness, and Epworth sleepiness scale (ESS) score. Severe sleepiness at 04:00–06:00 h was especially problematic in the 6/6 watch system among evening types and among the bridge officers with high ESS. The results suggest the 6/6 watch system is related to a higher risk of severe sleepiness during the early morning hours compared to the 4/8 and the other watch systems assessed.

Sleep disturbances and impaired daytime functioning in outpatients with newly diagnosed lung cancer

Clinical experience suggests that lung cancer (LC) is associated with sleep disturbances that may contribute to impaired daytime functioning and quality of life. Using questionnaires and home actigraphic recordings, we tried to determine whether sleep quality and daytime alertness are impaired in patients with newly diagnosed LC. Twenty-nine outpatients with newly diagnosed LC and an Eastern Cooperative Oncology Group performance status </=2 and 14 age- and sex-matched non-cancer (NC) patients with successfully treated sleep apnea were enrolled in the study. Sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI) and by night actigraphic data. Daytime alertness was assessed by the Epworth Sleepiness Scale (ESS) and day actigraphic data. The medical outcomes study 36-item short form (SF-36) was used for quality of life assessment. LC patients had higher PSQI (9.6+/-3.7 versus 5.6+/-3.2; p<0.001) and higher ESS (8.6+/-3.7 versus 5.6+/-3.2; p=0.01) than NC patients indicating worse quality of sleep and more excessive daytime sleepiness. Both physical and mental components score of SF-36 were lower in LC patients (p<0.001) indicating lower quality of life. Wrist actigraphy data showed significantly lower sleep efficiency and a higher sleep fragmentation during the night and lower mean activity during the day in LC patients. Patients with newly diagnosed LC and performance status </=2 present marked sleep disturbances, excessive daytime sleepiness and impaired quality of life. Further studies are required to determine the etiologic factors of sleep disturbances in LC patients and the impact of pharmacologic and non-pharmacologic interventions on sleep and daytime functioning.

Excessive Daytime Sleepiness and Subjective Sleep Quality in Patients with Nocturnal Frontal Lobe Epilepsy: A Case‐Control Study

Nocturnal frontal lobe epilepsy (NFLE) may be associated with sleep fragmentation and reduced sleep efficiency. Daytime sleepiness and disturbed sleep quality have been reported in some patients. We investigated the occurrence of daytime sleepiness-related symptoms and subjective sleep quality in patients with NFLE in comparison with matched controls. Patients with NFLE at a single epilepsy center and matched controls randomly selected from the general population self-administered questionnaires on daytime sleepiness-related symptoms and subjective sleep quality [Epworth sleepiness scale (ESS), Bologna questionnaire on sleepiness-related symptoms (BQS), Berlin questionnaire]. Thirty-three patients with NFLE and 27 controls were enrolled. "Tiredness after awakening" and "spontaneous mid-sleep awakenings" were more frequent in NFLE patients than in controls (36.4% versus 11.1%, p = 0.04, and 50.0% versus 22.2%, p = 0.03). The frequency of excessive daytime sleepiness (EDS) did not differ between groups. Posthoc analysis showed that patients with a complaint of "midsleep awakenings" had higher ESS and BQS scores than those without (7.3 versus 4.3, p = 0.004, and 5.0 versus 2.2, p = 0.001, respectively) and more frequent "tiredness after awakening" (56.3% versus 18.8%, p = 0.03). Patients with NFLE have no pathological level of EDS with respect to controls. However, daytime sleepiness-related symptoms could be more frequent in a subgroup of patients with subjective disturbed sleep quality, irrespective of the perceived frequency of seizures.

The range and nature of sleep dysfunction in untreated Parkinson's disease (PD). A comparative controlled clinical study using the Parkinson's disease sleep scale and selective polysomnography

In this study we have explored the nature and range of sleep dysfunction that occurs in untreated Parkinson's disease (PD) comparing data obtained from the use of the Parkinson's disease sleep scale (PDSS) in an untreated PD patient group compared to advanced PD and healthy controls. 25 untreated (drug-naive, DNPD) PD patients (mean age 66.9 years, range 53–80, 18 males) completed the validated Parkinson's disease sleep scale (PDSS), mean duration of PD was 2.1 years (1–10, up to 4 years in all except one patient with tremulous PD reporting tremor duration of 10 years) and mean Hoehn and Yahr score 1.9 (1–3). Data were compared to 34 advanced PD (mean age 70.2 years, range 51–88, 23 male), mean duration of PD 11 years (range 4–22), mean Hoehn and Yahr score 3.4 (3–5) and PDSS data obtained from 131 healthy controls (mean age 66.6 years, range 50–93, 56 males). Total PDSS scores and PDSS sub-items, except PDSS item 2, were highly significantly different ( p < 0.001) between DNPD, advanced PD and controls. Controls reported higher mean PDSS scores than both groups of patients, and advanced cases reported lower (mean ± S.D.) PDSS scores (86.95 ± 20.78) than drug-naive (105.72 ± 21.5) ( p < 0.001). Logistic regression analysis showed that items PDSS8 (nocturia), PDSS11 (cramps), PDSS12 (dystonia), PDSS13 (tremor), and PDSS15 (daytime somnolence) were significantly impaired in DNPD compared to controls while PDSS7 (nighttime hallucinations) additionally separated advanced PD from DNPD. In a subgroup of 11 advanced PD cases (mean age 62 years, range = 49–84 years, mean Hoehn and Yahr score 2.5, range = 1–3) with high Epworth Sleepiness Scale (ESS) scores (mean 14.5), low item 15 PDSS score (mean 4.7) and complaints of severe daytime sleepiness, underwent detailed overnight polysomnography (PSG) studies, all showing abnormal sleep patterns. We conclude that nocturia, nighttime cramps, dystonia, tremor and daytime somnolence seem to be the important nocturnal disabilities in DNPD and some of these symptoms may be reminiscent of “off” period related symptoms even though patients are untreated. Furthermore, polysomnography in “sleepy” PD patients may help diagnose unrecognised conditions such as periodic limb movement of sleep (PLMS), obstructive sleep apnoea (OSA) and REM Sleep Behaviour Disorder.

Excessive daytime sleepiness in patients with depressive disorder

To evaluate excessive daytime sleepiness in patients with depressive disorder and to examine its association with the severity of depression and suicidal ideation. Seventy patients were interviewed and assessed by the Epworth Sleepiness Scale (ESS), the Beck Depression Inventory (BDI) and the Beck Scale for Suicidal Ideation (SSI). Descriptive analysis, Pearson correlations and Student's t-test were used for data analyses. Most of the patients (57.1%) obtained high scores on the ESS. Correlation was positive and strongly significant between ESS scores and BDI scores, as well as between ESS scores and SSI scores. Patients with high ESS scores obtained higher mean BDI and SSI scores in comparison to patients with lower ESS scores. Significant differences (p < 0.05) were encountered when the patients with higher (> or = 10) and lower (< 10) ESS scores were compared in terms of total ESS, BDI and SSI scores. Excessive daytime sleepiness was frequent among patients and significantly associated with higher levels of depression and particularly with suicidal ideation. Thus, a careful investigation of daytime sleepiness in depressed patients is required during clinical evaluation.

Daytime sleepiness and hyperactivity in children with suspected sleep-disordered breathing.

Excessive daytime sleepiness (EDS) is seen less frequently as a presenting complaint in children with sleep-disordered breathing than in adults. Instead, symptoms of hyperactivity are often described. We hypothesized that children with suspected sleep-disordered breathing (S-SDB) were both sleepier and more hyperactive than control subjects. Furthermore, we hypothesized that overnight polysomnographic parameters correlated with sleepiness and hyperactivity. A cross-sectional study was conducted at a university-affiliated hospital and a community-based pediatric clinic. A total of 108 patients with S-SDB (mean [standard deviation] age: 7 +/- 4 years) and 72 control subjects (8 +/- 4 years) were recruited. A modified Epworth Sleepiness Scale (ESS) and the Conners Abbreviated Symptom Questionnaire were administered. Polysomnography was performed in patients with S-SDB. Patients with S-SDB had a higher ESS (8.1 +/- 4.9 vs 5.3 +/- 3.9) and a higher Conners score (12.8 +/- 7.6 vs 9.0 +/- 6.2) than control subjects. On the basis of adult criteria, 28% of patients had EDS. There was no difference in the ESS and Conners scores of patients with primary snoring and patients with obstructive sleep apnea. The ESS had weak correlations with polysomnographic parameters. Although the ESS score of children with S-SDB was within the normal range for adults, these children were sleepier and more hyperactive than control subjects. However, these data should be confirmed by a population-based study.

Sleep attacks, daytime sleepiness, and dopamine agonists in Parkinson's disease.

To study the putative association of dopamine agonists with sleep attacks in patients with Parkinson's disease (PD) and their relation to daytime sleepiness, we performed a survey of 2,952 PD patients in two German counties. In 177 patients, sudden, unexpected, and irresistible sleep episodes while engaged in some activity were identified in a structured telephone interview. Ninety-one of these patients denied the occurrence of appropriate warning signs. A total of 133 patients (75%) had an Epworth Sleepiness Scale (ESS) score >10; 65 (37%) >15. Thirty-one patients (18%) had an ESS score < or =10 and yet experienced sleep attacks without warning signs. Thus, although a significant proportion of patients at risk for sleep attacks might be identified using the ESS, roughly 1% of the PD patient population seems to be at risk for sleep attacks without appropriate warning signs and without accompanying daytime sleepiness. Sleep attacks occurred with all dopamine agonists marketed in Germany (alpha-dihydroergocryptine, bromocriptine, cabergoline, lisuride, pergolide, pramipexole, ropinirole), and no significant difference between ergot and nonergot drugs was evident. Levodopa (L-dopa) monotherapy carried the lowest risk for sleep attacks (2.9%; 95% confidence interval [CI], 1.7-4.0%) followed by dopamine agonist monotherapy (5.3%; 95% CI, 1.5-9.2%) and combination of L-dopa and a dopamine agonist (7.3%; 95% CI, 6.1-8.5%). Neither selegeline nor amantadine or entacapone appeared to influence the occurrence of sleep attacks. A high ESS score, intake of dopamine agonists, and duration of PD were the main influencing factors for the occurrence of sleep attacks. The odds ratio for dopamine agonist therapy was 2.9 compared to 1.9 with L-dopa therapy and 1.05 for a 1-year-longer disease duration.

Sleep apnoea in the Prader-Willi syndrome.

Seventeen children and young adults with the Prader-Willi syndrome were investigated. Twelve of 17 subjects had excessive daytime sleepiness as determined by their own or parental report, a high Epworth Sleepiness Scale score or a short mean sleep latency. Night sleep disturbances were reported in seven subjects with snoring, mouth-breathing, breath-holding and occasional nocturnal enuresis. Polysomnography showed abnormalities of sleep structure with rapid eye movements without reduction in muscle tone at sleep onset in 12 subjects, and a high respiratory event index with frequent brief apnoeas, particularly in REM sleep, in 16 subjects. Most apnoeas were not accompanied by arousals. Seven subjects, all of whom were obese, were considered to have symptomatic sleep apnoea and were treated with continuous positive airway pressure (CPAP) but this was poorly tolerated in two. Five subjects continued CPAP over a 6-month period resulting in subjective improvement in excessive daytime sleepiness in 3. Excessive daytime sleepiness occurs in approximately two-thirds of subjects with the Prader-Willi syndrome. It is mainly of central origin but obstructive sleep apnoea may increase sleepiness, particularly in obese subjects.