Automatic sleep analysis--II. Determination of sleep stages

The presented automatic sleep analysis is based on the time courses of the mean amplitudes of EEG (delta, beta and alpha bands), EMG and motility and specific patterns (spindles, REMs, delta waves greater than 40 microV) detected automatically. The interindividual variability of the parameters is taken into consideration by interactively determining the threshold levels. Sleep stages are classified for every epoch using context free decision rules according to the manual of Rechtschaffen and Kales. The resulting cyclograms are smoothed and corrected using context sensitive rules which considers the successive epochs and the probability of stage transitions.     

Weak association between sleep bruxism and obstructive sleep apnea. A sleep laboratory study

Purpose

No definitive associations or causal relationships have been determined between obstructive sleep apnea-hypopnea (OSAH) and sleep bruxism (SB). The purpose of this study was to investigate, in a population reporting awareness of both OSAH and SB, the associations between each specific breathing and jaw muscle event.

Methods

Polysomnography and audio–video data of 59 patients reporting concomitant OSAH and SB history were analyzed. Masseteric bursts after sleep onset were scored and classified into three categories: (1) sleep rhythmic masticatory muscle activity with SB (RMMA/SB), (2) sleep oromotor activity other than RMMA/SB (Sleep-OMA), and (3) wake oromotor activity after sleep onset (Wake-OMA).

Spearman’s rank correlation coefficient analyses were performed. Dependent variables were the number of RMMA/SB episodes, RMMA/SB bursts, Sleep-OMA, and Wake-OMA; independent variables were apnea-hypopnea index (AHI), arousal index(AI), body mass index(BMI), gender, and age.

Results

Although all subjects had a history of both SB and OSAH, sleep laboratory results confirmed that these conditions were concomitant in only 50.8 % of subjects. Moderate correlations were found in the following combinations (p?<?0.05); RMMA/SB episode with AI, RMMA/SB burst with AI and age, Sleep-OMA burst with AHI, and Wake-OMA burst with BMI.

Conclusions

The results suggest that (1) sleep arousals in patients with concomitant SB and OSAH are not strongly associated with onset of RMMA/SB and (2) apnea-hypopnea events appear to be related to higher occurrence of other types of sleep oromotor activity, and not SB activity. SB genesis and OSAH activity during sleep are probably influenced by different mechanisms.

     

Prevalence of sleep disturbances: Sleep disordered breathing,short sleep duration,and non-restorative sleep

Recently, interest in sleep disturbances, such as sleep disordered breathing (SDB), short sleep duration, and non-restorative sleep (NRS), has been increasing. The potentially large public health implications of sleep disturbances indicate a need to determine their prevalence in a general population. This review describes the characteristics of population-based sleep cohorts from past to present. Unavoidable methodological and baseline characteristic heterogeneity was found between studies. The prevalence of SDB (apnea hypopnea index (AHI), respiratory disturbance index (RDI), or oxygen desaturation index (ODI) ≥5/h) was 24.0–83.8% in men and 9.0–76.6% in women, and that of moderate-to-severe SDB (AHI, RDI, or ODI ≥15/h) was 7.2–67.2% in men and 4.0–50.9% in women. Additionally, the prevalence of SDB in post-menopausal women was 3–6 times higher than in pre-menopausal women. The prevalence of subjective short sleep duration (<6 h) was 7.5–9.6%, while that of objective short sleep duration (<6 h) was 22.1–53.3%. The prevalence of NRS was 19.2–31.0% in men and 26.3–42.1% in women, as determined from studies using a yes-no questionnaire, while a multi-national survey using a telephone-based expert system showed a wide range of prevalence between countries, from 2.4% to 16.1%. An association between SDB, short sleep duration, and NRS has recently been suggested. To gain a better understanding of the burden of sleep disturbances, a consensus on the definition of several sleep disturbances is needed, as methodological heterogeneity exists, including SDB scoring rules, subjective versus objective data collection for short sleep duration, and the definition of NRS itself.     

Relationship between sleep bruxism and sleep respiratory events in patients with obstructive sleep apnea syndrome

Purpose

Both obstructive sleep apnea syndrome (OSAS) and sleep bruxism (SB) are commonly related to arousal events. In this study, we examined the effect of SB on the sleep architecture and investigated the relationship between SB and sleep respiratory events in patients with OSAS.

Methods

Patients with OSAS (n?=?67) in whom apnea/hypopnea occurred five or more times per hour were recruited to this study. Healthy volunteers (n?=?16) were recruited as controls. None of the healthy volunteers had any sleep disorders or medical disorders, nor had they taken any medication or alcohol. Data were collected by standard polysomnography during overnight sleep tests in a dark, quiet room.

Results

The frequency of SB was higher in the OSAS than in the control group. The risk of SB was significantly higher in the OSAS than in the control group (odds ratio, 3.96; 95 % confidence interval, 1.03–15.20; P?OSAS than in the control group.

Conclusions

We found that patients with OSAS have a high risk of SB. In particular, this is the first report relating phasic-type SB to obstructive apnea events. This relationship suggests that improvement in OSAS might prevent exacerbations of SB.     

Obstructive sleep apnoea syndrome promotes reversal albuminuria during sleep

Introduction  

Sleep apnoea syndrome (OSAS) may induce albuminuria during sleep which could reflect one of the possible pathogenetic mechanisms regarding cardiovascular risk.     

Electrocardiogram-based sleep analysis for sleep apnea screening and diagnosis

Sleep and Breathing - Despite the increasing number of research studies of cardiopulmonary coupling (CPC) analysis, an electrocardiogram-based technique, the use of CPC in underserved population...     

Optogenetically induced sleep spindle rhythms alter sleep architectures in mice

Sleep spindles are rhythmic patterns of neuronal activity generated within the thalamocortical circuit. Although spindles have been hypothesized to protect sleep by reducing the influence of external stimuli, it remains to be confirmed experimentally whether there is a direct relationship between sleep spindles and the stability of sleep. We have addressed this issue by using in vivo photostimulation of the thalamic reticular nucleus of mice to generate spindle oscillations that are structurally and functionally similar to spontaneous sleep spindles. Such optogenetic generation of sleep spindles increased the duration of non-rapid eye movement (NREM) sleep. Furthermore, the density of sleep spindles was correlated with the amount of NREM sleep. These findings establish a causal relationship between sleep spindles and the stability of NREM sleep, strongly supporting a role for the thalamocortical circuit in sleep regulation.     

Do patients with sleep apnea die in their sleep?

Patients with sleep apnea syndrome (SAS) show cardiac dysrhythmias in association with cyclical nocturnal hypoxemia; are they at risk of dying during sleep? To assess this claim, we reviewed the clinical course of 91 patients with polysomnographically documented SAS between July 1978 and June 1986. A control group was comprised of 35 patients who were referred with symptoms suggestive of SAS but had negative sleep studies. Follow-up was obtained by survey questionnaire. Nine of 91 SAS and four of 35 control patients had died by completion of the study. There were no statistically significant differences in mortality between the two groups. None of the SAS patients died in their sleep, but they reported a higher incidence of disability and vehicular mishaps than did control subjects. The findings in this study do not support the hypothesis that SAS patients are at increased risk of dying in their sleep.     

The impact of sleep duration in obstructive sleep apnea patients

Purpose

Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease. Strong associations have been reported among sleep duration, hypertension, obesity, and cardiovascular mortality. The authors hypothesize that sleep duration may play a role in OSA severity. The aim of this study is to analyze sleep duration in OSA patients.

Methods

Patients who underwent overnight polysomnography were consecutively selected from the Sleep Clinic of Universidade Federal de São Paulo database between March 2009 and December 2010. All subjects were asked to come to the Sleep Clinic at 8:00 a.m. for a clinical evaluation and actigraphy. Anthropometric parameters such as weight, height, hip circumference, abdominal circumference, and neck circumference were also measured.

Results

One hundred thirty-three patients were divided into four groups based on total sleep time, sleep efficiency, sleep latency, and wake after sleep onset: very short sleepers (n?=?11), short sleepers (n?=?21), intermediate sleepers (n?=?56), and sufficient sleepers (n?=?45). Apnea–hypopnea index (AHI) was higher in very short sleepers (50.18?±?30.86 events/h) compared with intermediate sleepers (20.36?±?14.68 events/h; p?=?0.007) and sufficient sleepers (23.21?±?20.45 events/h; p?=?0.02). Minimal and mean arterial oxygen saturation and time spent below 90 % oxygen saturation exhibited worse values in very short sleepers. After adjustment for gender, age, AHI, and body mass index, mean oxygen saturation was significantly associated to total sleep time (p?=?0.01).

Conclusions

In conclusion, the present study suggests that sleep duration may be associated to low mean oxygen saturation in OSA patients.     

The accuracy of subjective sleep time in sleep apnoea recordings

Total sleep time is important in investigations of obstructive sleep apnoea, since the diagnosis is usually based on the average number of apnoeas per hour of sleep. Sleep estimates instead of exact EEG-recorded total sleep time is often used in the clinical setting. However, an overestimated sleep time would underestimate the degree of the disease and vice versa. The purpose of this study was to investigate the accuracy of subjective sleep time and time-in-bed as sleep estimates. One hundred patients undergoing diagnostic polysomnography for suspected obstructive sleep apnoea were asked to estimate their sleep time in a questionnaire. Seventy-five patients were diagnosed as suffering from obstructive sleep apnoea syndrome. The mean difference between self-scored and EEG-recorded total sleep time was 4 +/- 74 min. However, 30% scored with a difference greater than 1 h. The intra-class correlation coefficient was fair (0.58, CI: 0.43-0.70). Fifty-three patients overestimated their sleep time and 47 patients underestimated it. All but four patients underestimated their number of awakenings (P<0.001). The mean difference between time-in-bed and EEG-recorded total sleep time was 110 +/- 63 min. This difference was significantly larger than the difference between subjective sleep time and EEG-recorded total sleep time (P<0.001). The intra-class correlation coefficient was poor (0.38, CI: 0.20-0.54). Mean AHI was 27 +/- 27 using subjective sleep time and did not change significantly compared with the mean AHI of 25 +/- 21 based on EEG-recorded total sleep time. Mean AHI decreased significantly to 20 +/- 17 (P<0.001) when time-in-bed was used. In conclusion, 'time-in-bed' time is a poor predictor of total sleep time and should not be used when calculating the apnoea-hypopnoea index. Subjective sleep time is better as an approximation, but the individual differences are large.     

Distinct associations between energy balance and the sleep characteristics slow wave sleep and rapid eye movement sleep

Context:Epidemiologically, an inverse relationship between body mass index (BMI) and sleep duration is observed. Intra-individual variance in the amount of slow wave sleep (SWS) or rapid eye movement (REM) sleep has been related to variance of metabolic and endocrine parameters, which are risk factors for the disturbance of energy balance (EB).Objective:To investigate inter-individual relationships between EB (EB=∣energy intake-energy expenditure∣, MJ/24?h), SWS or REM sleep, and relevant parameters in normal-weight men during two 48?h stays in the controlled environment of a respiration chamber.Subjects and methods:A total of 16 men (age 23±3.7 years, BMI 23.9±1.9?kg?m(-2)) stayed in the respiration chamber twice for 48?h to assure EB. Electroencephalography was used to monitor sleep (2330-0730 hrs). Hunger and fullness were scored by visual analog scales; mood was determined by State Trait Anxiety Index-state and food reward by liking and wanting. Baseline blood and salivary samples were collected before breakfast. Subjects were fed in EB, except for the last dinner, when energy intake was ad libitum.Results:The subjects slept on average 441.8±49?min per night, and showed high within-subject reliability for the amount of SWS and REM sleep. Linear regression analyses showed that EB was inversely related to the amount of SWS (r=-0.43, P<0.03), and positively related to the amount of REM sleep (r=0.40, P<0.05). Relevant parameters such as hunger, reward, stress and orexigenic hormone concentrations were related to overeating, as well as to the amount of SWS and REM sleep, however, after inclusion of these parameters in a multiple regression, the amount of SWS and REM sleep did not add to the explained variance of EB, which suggests that due to their individual associations, these EB parameters are mediator variables.Conclusion:A positive EB due to overeating, was explained by a smaller amount of SWS and higher amount of REM sleep, mediated by hunger, fullness, State Trait Anxiety Index-state scores, glucose/insulin ratio, and ghrelin and cortisol concentrations.     

Fibromyalgia and sleep

Chronic pain in fibromyalgia patients, together with its associated symptoms and co-morbidities, is now considered a result of dysregulated mechanisms in the central nervous system (CNS). As fibromyalgia patients often report sleep problems, the physiological processes that normally regulate sleep may be disturbed and overlap with other CNS dysfunctions. Although the mechanisms potentially linking chronic widespread pain, sleep alterations and mood disorders have not yet been proven, polysomnography findings in patients with fibromyalgia and non-restorative sleep and their relationships with clinical symptoms support the hypothesis of a conceptual common mechanism called 'central sensitisation'. Food and Drug Administration (FDA)-approved drugs for the treatment of fibromyalgia may benefit sleep, but their label does not include the treatment of fibromyalgia-associated sleep disorders. Non-pharmacological therapies (including a thorough sleep assessment) can be considered in the first-line treatment of non-restorative sleep, although they have not yet been fully investigated in patients with fibromyalgia. Both pharmacological and non-pharmacological treatments should be used cautiously in patients with fibromyalgia, bearing in mind the patients' underlying disorders and the potential interactions of the therapies.