Effect of Three Hypopnea Scoring Criteria on OSA Prevalence and Associated Comorbidities in the General Population.

STUDY OBJECTIVES: Apnea-hypopnea index (AHI) is the main polysomnographic measure to diagnose obstructive sleep apnea (OSA). We aimed to evaluate the effect of three standard hypopnea definitions on the prevalence of OSA and its association with cardiometabolic outcomes in the general population. METHODS: We analyzed data from the HypnoLaus study (Lausanne, Switzerland), in which 2,162 participants (51% women, 57 ± 19 years) underwent in-home full polysomnography. AHI was calculated using three hypopnea definitions: AASM1999 (≥ 50% decrease in airflow or lower airflow reduction associated with oxygen desaturation ≥ 3% or an arousal), AASM2007 (≥ 30% airflow reduction associated with ≥ 4% oxygen desaturation), and AASM2012(≥ 30% airflow reduction associated with ≥ 3% oxygen desaturation or an arousal). Participants underwent clinical assessment for hypertension, diabetes, and metabolic syndrome. RESULTS: Median AHI of AASM1999, AASM2007 and AASM2012 criteria were 10.9, 4.4, and 10.1 events/h, respectively. OSA prevalence defined as AHI ≥ 5, ≥ 15, and ≥ 30 events/h was 74.5%, 39.3%, and 16.3% using AASM1999; 46.9%, 18.8%, and 6.8% using AASM2007; and 72.2%, 36.6%, and 14.9% using AASM2012. Different AHI thresholds derived from AASM1999, AASM2007, and AASM2012 criteria, respectively, were associated with hypertension (11.5, 4.8, 10.7 events/h), diabetes (15.7, 7.1, 14.4 events/h), and metabolic syndrome (12.8, 5.5, 11.8 events/h). CONCLUSIONS: Hypopnea definition has a major effect on AHI and on OSA prevalence in the general population and, hence, important implications for public health policies. There is a twofold difference in the threshold above which an association with diabetes, hypertension, and metabolic syndrome is observed using AASM2007 compared to AASM1999 or AASM2012 criteria.

Impact of sex and menopausal status on the prevalence, clinical presentation, and comorbidities of sleep-disordered breathing.

OBJECTIVE: Sleep-disordered breathing (SDB) is currently considered as a unique condition, but it has been suggested that the prevalence, clinical presentation, and associated conditions may differ by sex or by menopausal status in women. We aimed to assess the prevalence of SDB and associated comorbidities in pre- and postmenopausal women compared with men. METHODS: Participants of the population-based HypnoLaus Sleep Cohort study underwent polysomnography in their home environment and had extensive phenotyping for diabetes, hypertension, metabolic syndrome, and depression. RESULTS: A total of 2121 subjects (age 40-85 [59 ± 11] years, body mass index 25.6 ± 4.1 kg/m2, 1024 men and 1097 women [769 postmenopausal]) were included. SDB prevalence based on an apnea-hypopnea index of >5/h, >15/h, >20/h, and ≥30/h, respectively, was 83.8%, 49.7%, 37.5%, and 22.0% in men; 35.1%, 8.6%, 3.3%, and 1.3% in premenopausal women; and 71.6%, 29.4%, 20.7%, and 10.1% in postmenopausal women. In multivariable models, SDB severity was significantly associated with hypertension in women (p = 0.007) (mainly in postmenopausal women) but not in men (p = 0.065), with diabetes in men (p = 0.021) but not in women overall (p = 0.853) or in postmenopausal women (p = 0.725), with metabolic syndrome in men (p = 0.002) and women (p < 0.001), and with depression in women (p = 0.007) but not in men (p = 0.853). CONCLUSION: SDB prevalence in this middle-aged to-older population was high, particularly in men and postmenopausal women. SDB was associated with hypertension and depression exclusively in women, whereas an association with diabetes was present only in men. These findings suggest that the SDB definition and management recommendations may need to be adapted to these groups' specificities.

Prevalence and Clinical Significance of Respiratory Effort-Related Arousals in the General Population.

STUDY OBJECTIVES: To determine the prevalence and clinical associations of respiratory effort-related arousals (RERA) in a general population sample. METHODS: A total of 2,162 participants (51.2% women, 58.5 ± 11.0 years old, body mass index [BMI] 25.6 ± 4.2 kg/m2) of a general population-based cohort (HypnoLaus, Switzerland) underwent full polysomnography at home. Each subject with a RERA index ≥ 5 events/h was compared with an age-, sex- and apnea-hypopnea index (AHI)-matched control without RERA. RESULTS: A RERA index ≥ 5 events/h was present in 84 participants (3.8%; 95% confidence interval: 3.2-4.8%). In 17 participants (0.8%; 95% confidence interval: 0.5-1.3%), RERAs were the predominant sleep breathing disorder and only one of them complained of excessive daytime sleepiness. Compared to matched controls, subjects with a RERA index ≥ 5 events/h were similar in terms of BMI (26.5 ± 3.5 versus 26.3 ± 4.8 kg/m2, P = .73), neck circumference (38.5 ± 3.3 versus 37.6 ± 3.7 cm, P = .10) and Epworth Sleepiness Scale score (6.7 ± 3.7 versus 6.0 ± 3.7, P = .22). Also, no differences were found for hypertension (21.4% versus 27.4%, P = .47), diabetes (7.1% versus 7.1%, P = 1.00), or metabolic syndrome (31.0% versus 23.8%, P = .39). CONCLUSIONS: In a middle-aged population-based cohort, the prevalence of a RERA index ≥ 5 events/h was low (3.8%) and was not associated with negative clinical outcomes when using the currently recommended scoring criteria of the American Academy of Sleep Medicine.

REM-associated sleep apnoea: prevalence and clinical significance in the HypnoLaus cohort.

This study determined the prevalence of rapid eye movement (REM) related sleep-disordered breathing (REM-SDB) in the general population and investigated the associations of REM-SDB with hypertension, metabolic syndrome, diabetes and depression.Home polysomnography (PSG) recordings (n=2074) from the population-based HypnoLaus Sleep Cohort (48.3% men, 57±11 years old) were analysed. The apnoea-hypopnoea index was measured during REM and non-REM sleep (as REM-AHI and NREM-AHI, respectively). Regression models were used to explore the associations between REM-SDB and hypertension, diabetes, metabolic syndrome and depression in the entire cohort and in subgroups with NREM-AHI <10 events·h-1 and total AHI <10 events·h-1The prevalence of REM-AHI ≥20 events·h-1 was 40.8% in the entire cohort. An association between increasing REM-AHI and metabolic syndrome was found in the entire cohort and in both the NREM-AHI and AHI subgroups (p-trend=0.014, <0.0001 and 0.015, respectively). An association was also found between REM-AHI ≥20 events·h-1 and diabetes in both the NREM-AHI <10 events·h-1 (odds ratio (OR) 3.12 (95% CI 1.35-7.20)) and AHI <10 events·h-1 (OR 2.92 (95% CI 1.12-7.63)) subgroups. Systolic and diastolic blood pressure were positively associated with REM-AHI ≥20 events·h-1REM-SDB is highly prevalent in our middle-to-older age sample and is independently associated with metabolic syndrome and diabetes. These findings suggest that an increase in REM-AHI could be clinically relevant.

Clinical significance of periodic limb movements during sleep: the HypnoLaus study.

OBJECTIVE: Periodic limb movements during sleep (PLMS) are prevalent in the general population, but their impact on sleep and association with cardiometabolic disorders are a matter of debate. METHODS: Data from 2162 participants (51.2% women, mean age 58.4 ± 11.1 years) of the population-based HypnoLaus study (Lausanne, Switzerland) were collected. Subjective sleep complaints and habits were assessed using the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale (ESS). Participants underwent a full polysomnography (PSG) at home and were evaluated for the presence of hypertension, diabetes, and metabolic syndrome. RESULTS: Participants with a PLMS index (PLMSI) > 15/h (28.6% of the sample) had longer subjective sleep latency (18.6 ± 17.2 vs. 16.1 ± 14.3 min, p = 0.014) and duration (7.1 ± 1.2 vs. 6.9 ± 1.1 h, p < 0.001) than participants with PLMSI ≤ 15/h. At the PSG, they spent more time in stage N2 sleep (49.0 ± 11.2 vs. 45.5 ± 9.8%, p < 0.001), less in stage N3 (17.6 ± 8.2 vs. 20.6 ± 8.4%, p < 0.001) and in REM sleep (20.3 ± 6.4 vs. 22.4 ± 6.0%, p < 0.001), and exhibited longer REM latency (104.2 ± 70.2 vs. 91.7 ± 58.6 min, p < 0.001) and higher arousal index (26.5 ± 12.3 vs. 19.2 ± 9.7 n/h, p < 0.001). Participants with a PLMSI > 15/h had a lower ESS scores and higher prevalence of hypertension, diabetes, and metabolic syndrome. Multivariate analysis adjusting for confounding factors confirmed the independent association of PLMSI > 15/h with subjective sleep latency and duration, and with objective sleep structure disturbances. However, the associations with sleepiness and cardiovascular risk factors disappeared. CONCLUSIONS: In our large middle-age European population-based sample, PLMSI > 15/h was associated with subjective and objective sleep disturbances but not with sleepiness, hypertension, diabetes, or metabolic syndrome.

Prevalence and determinants of rapid eye movement sleep behavior disorder in the general population.

STUDY OBJECTIVES: Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia associated with neurodegenerative synucleinopathies. Its prevalence is largely unknown. This study determined the prevalence and characteristics of RBD in the general population using gold-standard polysomnography. METHODS: Full polysomnographic data from 1,997 participants (age = 59 ± 11.1 years, 53.6% women) participating in a population-based study (HypnoLaus, Lausanne, Switzerland) were collected. Sleep-related complaints and habits were investigated using various sleep measures including the Munich Parasomnia Screening (MUPS) questionnaire, which includes two questions evaluating complex motor behaviors suggestive of RBD. Full polysomnography was performed at home. For participants screening positive for RBD, muscle activity during REM sleep was quantified to diagnose RBD. RESULTS: Three hundred sixty-eight participants endorsed dream-enactment behavior on either of the two MUPS questions, and 21 fulfilled polysomnographic criteria for RBD, resulting in an estimated prevalence of 1.06% (95% CI = 0.61-1.50), with no difference between men and women. Compared with RBD- participants, RBD+ took more frequently antidepressants and antipsychotics (23.8% vs. 5.4%, p = .005; 14.3% vs. 1.5%, p = .004, respectively) and were more frequently smokers or ex-smokers (85% vs. 56.6%, p = .011). On polysomnography, RBD+ had more stage N2 sleep (52 ± 11.5% vs. 46.3 ± 10.2%, p = .024) and less REM sleep (18 ± 6.4% vs. 21.9 ± 6.2%, p = .007), lower apnea-hypopnea index in REM sleep (3.8 ± 5.2 vs. 8.9 ± 13/hour, p = .035), and lower autonomic arousal index (31 ± 14.9 vs. 42.6 ± 19.5/hour, p = .002). CONCLUSIONS: In our middle-to-older age population-based sample, the prevalence of RBD was 1.06%, with no difference between men and women. RBD was associated with antidepressant and antipsychotic use and with minor differences in sleep structure.

Sleep characteristics and cognitive impairment in the general population: The HypnoLaus study.

OBJECTIVE: To assess the association between sleep structure and cognitive impairment in the general population. METHODS: Data stemmed from 580 participants aged >65 years of the population-based CoLaus/PsyCoLaus study (Lausanne, Switzerland) who underwent complete sleep evaluation (HypnoLaus). Evaluations included demographic characteristics, personal and treatment history, sleep complaints and habits (using validated questionnaires), and a complete polysomnography at home. Cognitive function was evaluated using a comprehensive neuropsychological test battery and a questionnaire on the participant's everyday activities. Participants with cognitive impairment (global Clinical Dementia Rating [CDR] scale score > 0) were compared with participants with no cognitive impairment (global CDR score = 0). RESULTS: The 291 participants with a CDR score > 0 (72.5 ± 4.6 years), compared to the 289 controls with CDR = 0 (72.1 ± 4.6 years), had significantly more light (stage N1) and less deep (stage N3) and REM sleep, as well as lower sleep efficiency, higher intrasleep wake, and higher sleepiness scores (all p < 0.05). Sleep-disordered breathing was more severe in participants with cognitive impairment with an apnea/hypopnea index (AHI) of 18.0 (7.8-35.5)/h (p50 [p25-p75]) (vs 12.9 [7.2-24.5]/h, p < 0.001), and higher oxygen desaturation index (ODI). In the multivariate analysis after adjustments for confounding variables, the AHI and the ODI ≥4% and ≥6% were independently associated with cognitive impairment. CONCLUSIONS: Participants aged >65 years with cognitive impairment have higher sleepiness scores and a more disrupted sleep. This seems to be related to the occurrence of sleep-disordered breathing and the associated intermittent hypoxia.

Comparison of Sleep Disorders between Real and Simulated 3,450-m Altitude.

STUDY OBJECTIVES: Hypoxia is known to generate sleep-disordered breathing but there is a debate about the pathophysiological responses to two different types of hypoxic exposure: normobaric hypoxia (NH) and hypobaric hypoxia (HH), which have never been directly compared. Our aim was to compare sleep disorders induced by these two types of altitude. METHODS: Subjects were exposed to 26 h of simulated (NH) or real altitude (HH) corresponding to 3,450 m and a control condition (NN) in a randomized order. The sleep assessments were performed with nocturnal polysomnography (PSG) and questionnaires. Thirteen healthy trained males subjects volunteered for this study (mean ± SD; age 34 ± 9 y, body weight 76.2 ± 6.8 kg, height 179.7 ± 4.2 cm). RESULTS: Mean nocturnal oxygen saturation was further decreased during HH than in NH (81.2 ± 3.1 versus 83.6 ± 1.9%; P < 0.01) when compared to NN (95.5 ± 0.9%; P < 0.001). Heart rate was higher in HH than in NH (61 ± 10 versus 55 ± 6 bpm; P < 0.05) and NN (48 ± 5 bpm; P < 0.001). Total sleep time was longer in HH than in NH (351 ± 63 versus 317 ± 65 min, P < 0.05), and both were shorter compared to NN (388 ± 50 min, P < 0.05). Breathing frequency did not differ between conditions. Apnea-hypopnea index was higher in HH than in NH (20.5 [15.8-57.4] versus 11.4 [5.0-65.4]; P < 0.01) and NN (8.2 [3.9-8.8]; P < 0.001). Subjective sleep quality was similar between hypoxic conditions but lower than in NN. CONCLUSIONS: Our results suggest that HH has a greater effect on nocturnal breathing and sleep structure than NH. In HH, we observed more periodic breathing, which might arise from the lower saturation due to hypobaria, but needs to be confirmed.

Sleep Characteristics in Early Stages of Chronic Kidney Disease in the HypnoLaus Cohort.

STUDY OBJECTIVES: To evaluate the association between early stages of chronic kidney disease (CKD) and sleep disordered breathing (SDB), restless legs syndrome (RLS), and subjective and objective sleep quality (SQ). METHODS: Cross-sectional analysis of a general population-based cohort (HypnoLaus). 1,760 adults (862 men, 898 women; age 59.3 (± 11.4) y) underwent complete polysomnography at home. RESULTS: 8.2% of participants had mild CKD (stage 1-2, estimated glomerular filtration rate [eGFR] ≥ 60 mL/min/1.73 m(2) with albuminuria) and 7.8% moderate CKD (stage 3, eGFR 30-60 mL/min/1.73 m(2)). 37.3% of our sample had moderate-to-severe SDB (apnea-hypopnea index [AHI] ≥ 15/h) and 15.3% had severe SDB (AHI ≥ 30/h). SDB prevalence was positively associated with CKD stages and negatively with eGFR. In multivariate analysis, age, male sex, and body mass index were independently associated with SDB (all P < 0.001), but kidney function was not. The prevalence of RLS was 17.5%, without difference between CKD stages. Periodic leg movements index (PLMI) was independently associated with CKD stages. Subjective and objective SQ decreased and the use of sleep medication was more frequent with declining kidney function. Older age, female sex, and the severity of SDB were the strongest predictors of poor SQ in multivariate regression analysis but CKD stage was also independently associated with reduced objective SQ. CONCLUSIONS: Patients with early stages of CKD have impaired SQ, use more hypnotic drugs, and have an increased prevalence of SDB and PLM. After controlling for confounders, objective SQ and PLMI were still independently associated with declining kidney function.

Prevalence and determinants of periodic limb movements in the general population.

OBJECTIVE: Periodic limb movements during sleep (PLMS) are sleep phenomena characterized by periodic episodes of repetitive stereotyped limb movements. The aim of this study was to describe the prevalence and determinants of PLMS in a middle to older aged general population. METHODS: Data from 2,162 subjects (51.2% women, mean age = 58.4 ± 11.1 years) participating in a population-based study (HypnoLaus, Lausanne, Switzerland) were collected. Assessments included laboratory tests, sociodemographic data, personal and treatment history, and full polysomnography at home. PLMS index (PLMSI) was determined, and PLMSI > 15/h was considered as significant. RESULTS: Prevalence of PLMSI > 15/h was 28.6% (31.3% in men, 26% in women). Compared to subjects with PLMSI ≤ 15/h, subjects with PLMSI > 15/h were older (p < 0.001), were predominantly males (p = 0.007), had a higher proportion of restless legs syndrome (RLS; p < 0.001), had a higher body mass index (p = 0.001), and had a lower mean glomerular filtration rate (p < 0.001). Subjects with PLMSI > 15/h also had a higher prevalence of diabetes, hypertension, and beta-blocker or hypnotic treatments. The prevalence of antidepressant use was higher, but not statistically significant (p = 0.07). Single nucleotide polymorphisms (SNPs) within BTBD9 (rs3923809), TOX3 (rs3104788), and MEIS1 (rs2300478) genes were significantly associated with PLSMI > 15/h. Conversely, mean hemoglobin and ferritin levels were similar in both groups. In the multivariate analysis, age, male gender, antidepressant intake, RLS, and rs3923809, rs3104788, and rs2300478 SNPs were independently associated with PLMSI > 15/h. INTERPRETATION: PLMS are highly prevalent in our middle-aged European population. Age, male gender, RLS, antidepressant treatment, and specific BTBD9, TOX3, and MEIS1 SNP distribution are independent predictors of PLMSI > 15/h.

Bad sleep? Don't blame the moon! A population-based study.

INTRODUCTION: The aim of this study was to evaluate if there is a significant effect of lunar phases on subjective and objective sleep variables in the general population. METHODS: A total of 2125 individuals (51.2% women, age 58.8 ± 11.2 years) participating in a population-based cohort study underwent a complete polysomnography (PSG) at home. Subjective sleep quality was evaluated by a self-rating scale. Sleep electroencephalography (EEG) spectral analysis was performed in 759 participants without significant sleep disorders. Salivary cortisol levels were assessed at awakening, 30 min after awakening, at 11 am, and at 8 pm. Lunar phases were grouped into full moon (FM), waxing/waning moon (WM), and new moon (NM). RESULTS: Overall, there was no significant difference between lunar phases with regard to subjective sleep quality. We found only a nonsignificant (p = 0.08) trend toward a better sleep quality during the NM phase. Objective sleep duration was not different between phases (FM: 398 ± 3 min, WM: 402 ± 3 min, NM: 403 ± 3 min; p = 0.31). No difference was found with regard to other PSG-derived parameters, EEG spectral analysis, or in diurnal cortisol levels. When considering only subjects with apnea/hypopnea index of <15/h and periodic leg movements index of <15/h, we found a trend toward shorter total sleep time during FM (FM: 402 ± 4, WM: 407 ± 4, NM: 415 ± 4 min; p = 0.06) and shorter-stage N2 duration (FM: 178 ± 3, WM: 182 ± 3, NM: 188 ± 3 min; p = 0.05). CONCLUSION: Our large population-based study provides no evidence of a significant effect of lunar phases on human sleep.

Scoring criteria for portable monitor recordings: a comparison of four hypopnoea definitions in a population-based cohort.

RATIONALE: Limited-channel portable monitors (PMs) are increasingly used as an alternative to polysomnography (PSG) for the diagnosis of obstructive sleep apnoea (OSA). However, recommendations for the scoring of PM recordings are still lacking. Pulse-wave amplitude (PWA) drops, considered as surrogates for EEG arousals, may increase the detection sensitivity for respiratory events in PM recordings. OBJECTIVES: To investigate the performance of four different hypopnoea scoring criteria, using 3% or 4% oxygen desaturation levels, including or not PWA drops as surrogates for EEG arousals, and to determine the impact of measured versus reported sleep time on OSA diagnosis. METHODS: Subjects drawn from a population-based cohort underwent a complete home PSG. The PSG recordings were scored using the 2012 American Academy of Sleep Medicine criteria to determine the apnoea-hypopnoea index (AHI). Recordings were then rescored using only parameters available on type 3 PM devices according to different hypopnoea criteria and patients-reported sleep duration to determine the 'portable monitor AHIs' (PM-AHIs). MAIN RESULTS: 312 subjects were included. Overall, PM-AHIs showed a good concordance with the PSG-based AHI although it tended to slightly underestimate it. The PM-AHI using 3% desaturation without PWA drops showed the best diagnostic accuracy for AHI thresholds of ≥ 5/h and ≥ 15/h (correctly classifying 94.55% and 93.27% of subjects, respectively, vs 80.13% and 87.50% with PWA drops). There was a significant but modest correlation between PWA drops and EEG arousals (r=0.20, p=0.0004). CONCLUSION: Interpretation of PM recordings using hypopnoea criteria which include 3% desaturation without PWA drops as EEG arousal surrogate showed the best diagnosis accuracy compared with full PSG.

Age and gender variations of sleep in subjects without sleep disorders.

OBJECTIVE: Although sleep is a biomarker for general health and pathological conditions, its changes across age and gender are poorly understood. METHODS: Subjective evaluation of sleep was assessed by questionnaires in 5,064 subjects, and 2,966 were considered without sleep disorders. Objective evaluation was performed by polysomnography in 2,160 subjects, and 1,147 were considered without sleep disorders. Only subjects without sleep disorders were included (aged 40-80 years). RESULTS: Aging was strongly associated with morning preference. Older subjects, especially women, complained less about sleepiness, and pathological sleepiness was significantly lower than in younger subjects. Self-reported sleep quality and daytime functioning improved with aging. Sleep latency increased with age in women, while sleep efficiency decreased with age in both genders. Deep slow-wave sleep decreased with age, but men were more affected. Spectral power densities within slow waves (< 5 Hz) and fast spindles (14-14.75 Hz) decreased, while theta-alpha (5-1 Hz) and beta (16.75-25 Hz) power in non-rapid eye movement sleep increased with aging. In REM sleep, aging was associated with a progressive decrease in delta (1.25-4.5 Hz) and increase in higher frequencies. CONCLUSIONS: Our findings indicate that sleep complaints should not be viewed as part of normal aging but should prompt the identification of underlying causes.

Oscillating Positive Airway Pressure Versus CPAP for the Treatment of Obstructive Sleep Apnea.

Although continuous positive airway pressure (CPAP) is the most effective therapy for obstructive sleep apnea (OSA), it is not always well tolerated by the patients. Previous physiological studies showed that pressure oscillations applied to the pharynx could activate upper airway muscles, but it is not clear whether these pressure oscillations could be tolerated during sleep in OSA patients. The aim of this study was to assess the tolerance of oscillating positive airway pressure (O-PAP) (a CPAP device delivering high-frequency pressure oscillations to the upper airway) compared to CPAP. Fourteen OSA patients currently on CPAP [age 59.9 ± 10.1 years old, BMI 34.8 ± 7.2 kg/m(2), initial apnea-hypopnea index (AHI): 58.7 ± 25.2 events/h] used O-PAP or CPAP on two consecutive nights under polysomnography, in a single-blind randomized crossover design to assess sleep quality. A subtherapeutic pressure (70% of the optimal titrated pressure) was applied in both conditions and the residual AHI with each technique was also compared. There was no difference in measured or perceived sleep quality between the two treatment modalities (sleep efficiency 90.0% versus 88.1%, p = 0.54). Despite the small sample, we also found a trend toward a decrease in residual respiratory events with O-PAP compared to CPAP (median AHI 14.3 versus 20.5/h, p = 0.194). The good tolerance of O-PAP and the positive trend toward a reduction in residual AHI should stimulate further research on the effects of O-PAP in OSA patients.

Objective sleep structure and cardiovascular risk factors in the general population: the HypnoLaus Study.

STUDY OBJECTIVES: To evaluate the association between objective sleep measures and metabolic syndrome (MS), hypertension, diabetes, and obesity. DESIGN: Cross-sectional study. SETTING: General population sample. PARTICIPANTS: There were 2,162 patients (51.2% women, mean age 58.4 ± 11.1). INTERVENTIONS: Patients were evaluated for hypertension, diabetes, overweight/obesity, and MS, and underwent a full polysomnography (PSG). MEASUREMENTS AND RESULTS: PSG measured variables included: total sleep time (TST), percentage and time spent in slow wave sleep (SWS) and in rapid eye movement (REM) sleep, sleep efficiency and arousal index (ArI). In univariate analyses, MS was associated with decreased TST, SWS, REM sleep, and sleep efficiency, and increased ArI. After adjustment for age, sex, smoking, alcohol, physical activity, drugs that affect sleep and depression, the ArI remained significantly higher, but the difference disappeared in patients without significant sleep disordered breathing (SDB). Differences in sleep structure were also found according to the presence or absence of hypertension, diabetes, and overweight/obesity in univariate analysis. However, these differences were attenuated after multivariate adjustment and after excluding subjects with significant SDB. CONCLUSIONS: In this population-based sample we found significant associations between sleep structure and MS, hypertension, diabetes, and obesity. However, these associations were cancelled after multivariate adjustment. We conclude that normal variations in sleep contribute little if any to MS and associated disorders.