Associations among chronic obstructive pulmonary disease and sleep-disordered breathing in an urban male working population in Japan.

BACKGROUND: There are few reports about sleep disturbances in patients with chronic obstructive pulmonary disease (COPD) in Asian countries. OBJECTIVES: To investigate the associations between sleep-disordered breathing (SDB) with hypoxemia and sleep quality, including sleep duration, in patients with COPD, we measured SDB and sleep quality including the objective sleep duration determined by an actigraph and portable monitoring. METHODS: A cross-sectional epidemiological health survey of 303 male employees (means ± SD: age 43.9 ± 8.2 years; BMI 24.0 ± 3.1) was conducted. Sleep quality was measured using the Epworth Sleepiness Scale (ESS) and the Pittsburgh Sleep Quality Index (PSQI). A respiratory disturbance index (RDI) ≥5 indicated SDB. RESULTS: Nineteen subjects (6.3%) had COPD. Among these, 11 (3.6%) had COPD with SDB (overlap syndrome). Sleep duration, ESS, and PSQI scores were not significantly different between COPD patients and normal control subjects. However, COPD patients had significantly longer sleep latency (p = 0.019), a lower sleep efficiency (p = 0.017), and a higher sleep fragmentation index (p = 0.041) and average activity (p = 0.0097) during sleep than control subjects. They also had a significantly higher RDI and more severe desaturation during sleep than control subjects (p < 0.01). The differences remained after adjustment for age and BMI but disappeared following adjustment for RDI. CONCLUSIONS: COPD patients with even mild-to-moderate airflow limitations had nocturnal desaturation and RDI-related impaired sleep quality without significant symptoms.

Differences in relationships among sleep apnoea, glucose level, sleep duration and sleepiness between persons with and without type 2 diabetes.

Obstructive sleep apnoea is common in patients with diabetes. Recently, it was reported that short sleep duration and sleepiness had deleterious effects on glucose metabolism. Thereafter, several reports showed relationships between glucose metabolism and obstructive sleep apnoea, sleep duration or sleepiness. But the interrelationships among those factors based on recent epidemiological data have not been examined. We analysed data on 275 male employees (age, 44±8years; body mass index, 23.9±3.1kg m(-2) ) who underwent a cross-sectional health examination in Japan. We measured fasting plasma glucose, sleep duration using a sleep diary and an actigraph for 7days, and respiratory disturbance index with a type 3 portable monitor for two nights. Fifty-four subjects (19.6%) had impaired glucose metabolism, with 21 having diabetes. Of those 21 (body mass index, 25.9±3.8kgm(-2) ), 17 (81.0%) had obstructive sleep apnoea (respiratory disturbance index≥5). Regarding the severity of obstructive sleep apnoea, 10, four and three had mild, moderate and severe obstructive sleep apnoea, respectively. The prevalence of obstructive sleep apnoea was greater in those with than without diabetes (P=0.037). Multiple regression analyses showed that the respiratory disturbance index independently related to fasting plasma glucose only in the diabetic subjects. In patients with diabetes, after adjustment for age, waist circumference, etc. sleep fragmentation had a greater correlation with fasting plasma glucose than sleep duration, but without significance (P=0.10). Because the prevalence of obstructive sleep apnoea is extremely high in patients with diabetes, sufficient sleep duration with treatment for obstructive sleep apnoea, which ameliorates sleep fragmentation, might improve fasting plasma glucose.

Effects of the presence of hypertension on the relationship between obstructive sleep apnoea and sleepiness.

Obstructive sleep apnoea (OSA) plays a significant role in increasing blood pressure. Significant decreases were reported in blood pressure of hypertensive OSA patients with sleepiness who underwent continuous positive airway pressure (CPAP) treatment, but not in non-sleepy hypertensive OSA patients. More recently, however, significant decreases in blood pressure in non-sleepy hypertensive OSA patients following CPAP were shown. Effects of sleepiness on hypertension in OSA patients have been investigated, but not the effects of hypertension on sleepiness in OSA patients. We investigated the relationships between hypertension and sleepiness in patients with OSA. We analysed data on 275 middle-aged male subjects from a cross-sectional epidemiological health survey. We measured blood pressure and sleep duration objectively using an actigraph for 7 days and the respiratory disturbance index (RDI) with a type 3 portable device for 2 nights, and assessed sleepiness using the Epworth Sleepiness Scale (ESS). The RDI correlated significantly with ESS scores in the 88 hypertensive subjects (r = 0.33, P = 0.0024), but not in the 187 non-hypertensive subjects (r = -0.01, P = 0.91). Short sleep duration correlated significantly with ESS scores in both groups. Both the RDI and short sleep duration were related independently to sleepiness in only hypertensive subjects. Furthermore, the RDI was related negatively significantly to sleep duration in hypertensive subjects. Although short sleep duration was related significantly to sleepiness in both groups, hypertension may be important for the sleepiness in OSA patients. Detailed mechanisms of the difference in the relationship between sleepiness and the severity of OSA with or without hypertension should be studied further.

Associations between obstructive sleep apnea, metabolic syndrome, and sleep duration, as measured with an actigraph, in an urban male working population in Japan.

BACKGROUND: Severe obstructive sleep apnea (OSA), metabolic syndrome (Mets) and short sleep duration are all risk factors for cardiovascular events. There has been no report which has investigated this relationship in an age- and BMI-matched population-based study. The prevalence of OSA in Mets subjects has not been established, although the converse (i.e., the prevalence of Mets in OSA subjects) has been investigated several times. METHODS: This home cardiorespiratory (type 3) sleep study, using an actigraph, was conducted in 275 males working for an urban company. Retrospective measurements of fasting blood parameters were obtained from the company's periodical inspection data. The mean duration between the sleep study and the measurement of blood parameters was 213 days. RESULTS: Although there was a significant relationship between OSA severity and the prevalence of Mets (P < 0.001), the association between severity and Mets was not significant after adjustments were made for age and BMI. Severe OSA was 7.8 times as likely to be present in subjects with Mets (16.2% of all 68 Mets subjects) as those without (2.4% of 207 non-Mets) (P < 0.001). Subject with severe OSA had a significantly short sleep duration (P < 0.05). Sleep duration in Mets subjects was also significantly shorter than in those without (P < 0.05). CONCLUSIONS: Although increased BMI and age both had a significant effect on the prevalence of OSA in patients with Mets, one of 6 subjects with Mets, but only one of 40 without Mets had severe OSA in an urban male population in Japan. Physicians should take into account this high prevalence of severe OSA in patients with Mets. Sleep duration should be taken into consideration as an important factor in studies investigating the prevalence of severe OSA and Mets.

Sleep-disordered breathing in the usual lifestyle setting as detected with home monitoring in a population of working men in Japan.

STUDY OBJECTIVES: To examine (1) the prevalence of home-monitored sleep-disordered breathing (SDB) and obstructive sleep apnea syndrome in a Japanese working population and (2) whether home monitoring with a type 3 portable monitor and actigraphy can produce reliable data to analyze SDB in usual lifestyles. METHODS: A cross-sectional survey using a self-administered questionnaire was conducted on a group of employees at a wholesale company in Osaka, Japan. Examinations by physicians and by sleep monitoring were also performed. Unattended home cardiorespiratory (type 3) sleep studies with actigraphy were conducted for 2 nights to diagnose SDB in 322 subjects. From the baseline questionnaires and sleep diaries, participants were assessed to follow their usual lifestyles during the study (e.g., time in bed, alcohol intake). RESULTS: Of 466 Japanese male employees, 396 responded to the questionnaire survey (85.0%). Results from 322 male employees aged 23 to 59 (43.8 +/- 8.4 years) were analyzed. Respiratory disturbance index (RDI), calculated from the type 3 portable monitors and actigraphy, was highly reliable with an intraclass correlation of 0.98 for interscorer reliability and with an intraclass correlation of 0.95 for night-to-night reliability. Prevalence of mild (5 < or = RDI < 15), moderate (15 < or = RDI < 30) and severe (RDI < or = 30) SDB in this population were 37.4%, 15.7%, and 6.6%, respectively. The prevalence of obstructive sleep apnea syndrome (RDI > or = 5 and Epworth Sleepiness Scale score > 10) was 17.6%. CONCLUSIONS: The prevalence of moderate to severe SDB (RDI > or = 15) was 22.3% in this Japanese male working population aged 23 to 59, measured in participant's usual life settings. Unattended home monitoring with type 3 portable monitors and actigraphy was highly reliable and may be suitable for analyzing SDB in the usual lifestyle setting.

Association between sleep apnea, sleep duration, and serum lipid profile in an urban, male, working population in Japan.

BACKGROUND: Dyslipidemia is often comorbid with obstructive sleep apnea (OSA), but few population-based studies have investigated their relationship. Short sleep duration is associated with hypertension and diabetes; however, its association with dyslipidemia is not well known. We investigated relationships among OSA, sleep duration, and the lipid profile in a community-based study. METHODS: We measured the respiratory disturbance index (RDI) and sleep duration by a type 3 portable device and actigraph in 275 men in a Japanese company. Fasting blood parameters were obtained from periodic inspection data. RESULTS: According to Japanese criteria, 143 subjects had dyslipidemia. Percent sleep time of oxygen saturation as measured by pulse oximetry (SpO2) < 90% and prevalence of severe OSA were greater and sleep duration and mean SpO2 during sleep were lower in subjects with dyslipidemia than in those without. Univariate analysis showed that the RDI was positively correlated with serum triglyceride (TG) levels (ρ = 0.20, P < .01), and sleep duration was negatively correlated with serum total cholesterol (TC) levels (γ = -0.13, P = .03) and serum low-density lipoprotein cholesterol levels (γ = -0.12, P = .04). Stepwise multiple regression analysis revealed that TG was correlated with RDI (ß = 0.14, P = .02), BMI (ß = 0.20, P < .01), and alcohol intake (ß = 0.20, P < .01), and that TC was correlated with sleep duration (ß = -0.13, P = .03), age (ß = 0.15, P = .02), and waist/hip ratio (ß = 0.15, P = .02). CONCLUSIONS: Short sleep duration was associated with TC levels and RDI was positively associated with TG levels among working-aged men in an urban Japanese company. Correcting the status of OSA and/or short sleep duration might improve the lipid profile and cardiovascular consequences.

Relationships of decreased lung function with metabolic syndrome and obstructive sleep apnea in Japanese males.

OBJECTIVE: Decreased lung function as assessed by forced vital capacity (FVC) and forced expiratory volume in one second (FEV(1)) is shown to be associated with cardiovascular morbidity and mortality. Although the underlying mechanisms for this association remain unknown, metabolic syndrome and obstructive sleep apnea (OSA) may have a role. We analyzed the relationships between metabolic syndrome and OSA in a cross-sectional health survey of middle-aged male employees. METHODS: In this secondary analysis, we re-analyzed the relationships of lung function determined by spirometry with metabolic syndrome and OSA based on the respiratory disturbance index (RDI) with a type 3 portable monitor. RESULTS: We analyzed 273 subjects. Independent of age, body mass index (BMI) and smoking, quartiles for lower FVC and FEV(1) were associated with a higher risk of metabolic syndrome compared with quartiles for the highest FVC and FEV(1), respectively. A similar trend was observed regarding the risk associated with waist circumference, and in FVC cases, dyslipidemia. The risk of hyperglycemia was significantly higher in quartiles for the second lowest FVC and FEV(1) than in quartiles for the highest FVC and FEV(1), respectively. A significant trend for an increase in RDI was observed in accordance with quartiles for lower FVC, but not FEV(1). CONCLUSION: There was a significant relationship between lung function impairment and metabolic syndrome through mainly abdominal obesity, partially through hyperglycemia, and also through dyslipidemia, but only with respect to restrictive lung function. Restrictive lung function was also related to OSA. This epidemiologic evidence may indicate underlying mechanisms between decreased lung function and cardiovascular risk.

Dorsolateral prefrontal cortical oxygenation during REM sleep in humans.

Previous neuroimaging studies that examined cerebral blood flow during rapid eye movement (REM) sleep have reported inconsistent findings regarding the activity of the dorsolateral prefrontal cortex (DLPFC). Although most previous positron emission tomography (PET) studies failed to detect DLPFC activation during REM sleep, several studies have observed DLPFC activation, possibly reflecting transient prefrontal activities related to REM. More recently, an event-related functional magnetic resonance imaging (fMRI) study observed REM-locked activation of the DLPFC during REM sleep. The present study investigated hemodynamic changes of the DLPFC throughout the REM sleep period in 25 subjects using near-infrared spectroscopy. Continuous monitoring of changes in the hemoglobin (Hb) concentration and tissue oxygenation index (TOI, proportion of oxygenated-Hb to total-Hb) in the bilateral DLPFC was conducted every 0.5s, simultaneously with polysomnographic recordings. Eight of the 25 subjects showed REM sleep, and all indicated a clear increase in both the oxygenated-Hb concentration and TOI from baseline at the occurrence of first REM, relative to prior stage 2 sleep. The results indicate that the appearance of the first REM that occurred just after onset of the REM sleep closely coincides with the activation of the DLPFC, which could play a role in cognitive activities during REM sleep in humans.