Effects of body position on snoring in apneic and nonapneic snorers

STUDY OBJECTIVES: The positional dependency of obstructive sleep apnea (OSA) is well known, but objective evidence for the positional effect on snoring is lacking. The aim of this study is to elucidate the effect of body position on snoring, and that of sleep stage as well. DESIGN: Retrospective analysis of the effects of body position and sleep stage on snoring in nonapneic snorers (snorer group) and OSA patients (apneic group). SETTING: A sleep laboratory in a national hospital in Japan. PATIENTS: Seventy-two patients who complained of habitual snoring and underwent overnight polysomnography. INTERVENTIONS: N/A MEASUREMENTS AND RESULTS: In the lateral position, most subjects in the snorer group showed decreased snoring both in time (p = 0.0004) and intensity (p = 0.0003), but subjects in the apneic group showed variable changes. In the apneic group, the positional dependency of snoring (the ratio of lateral value to supine value) was correlated with supine apnea-hypopnea index (AHI), that is, OSA patients with higher supine AHI tended to show increased snoring in the lateral position. AS to the effect of sleep stage, snoring was increased in deeper non-rapid eye movement sleep and decreased in rapid eye movement sleep in a given position. CONCLUSIONS: This study demonstrated that the positional dependency is different between nonapneic snorers and OSA patients. Most of the nonapneic snorers snore less in the lateral position than in the supine position in contrast to OSA patients who often fail to decrease snoring even in the lateral position.     

Objective snoring time and carotid intima‐media thickness in non‐apneic female snorers

Controversy persists about whether snoring can affect atherosclerotic changes in adjacent vessels, independently of obstructive sleep apnea and other cardiovascular risk factors. This study examined the independent association between snoring and carotid artery intima‐media thickness (IMT) in non‐apneic snorers and non‐snorers. We studied 180 non‐apneic snorers and non‐snorers participating in a full‐night home‐based sleep study. Snoring sound was measured objectively by a microphone. Based on snoring time across the night, participants were classified as non‐snorers (snoring time: 0%), mild snorers (1–25%) and moderate to heavy snorers (≥25%). We measured IMT on both common carotid arteries. The three groups were matched by age, body mass index, cholesterol, blood pressure and glucose levels, using weights from generalized boosted‐propensity score models. Mean carotid IMT increased with increased snoring time across the night in women: non‐snorers (0.707 mm), mild (0.718 mm) and moderate to heavy snorers (0.774 mm), but not in men. Snoring during at least one‐fourth of a night's sleep is associated independently with subclinical changes in carotid IMT in women only.     

Intra-subject variability of snoring sounds in relation to body position, sleep stage, and blood oxygen level

In a multidimensional feature space, the snoring sounds can extend from a very compact cluster to highly distinct clusters. In this study, we investigated the cause of snoring sound’s variation within the snorers. It is known that a change in body position and sleep stage can affect snoring during sleep but it is unclear whether positional, sleep state, and blood oxygen level variations cause the snoring sounds to have different characteristics, and if it does how significant that effect would be. We extracted 12 characteristic features from snoring sound segments of 57 snorers and transformed them into a 4-D feature space using principal component analysis (PCA). Then, they were grouped based on the body position (side, supine, and prone), sleep stage (NREM, REM, and Arousal), and blood oxygen level (Normal and Desaturation). The probability density function of the transformed features was calculated for each class of categorical variables. The distance between the class-densities were calculated to determine which of these parameters affects the snoring sounds significantly. Analysis of Variance (ANOVA) was run for each categorical variable. The results show that the positional change has the highest effect on the snoring sounds; it results in forming distinct clusters of snoring sounds. Also, sleep state and blood oxygen level variation have been found to moderately affect the snoring sounds.     

Determining optimal sleep position in patients with positional sleep-disordered breathing using response surface analysis

A lateral position (LP) during sleep is effective in reducing sleep disorder symptoms in mild or moderate sleep apnea patients. However, the effect of head and shoulder posture in LP on reducing sleep disorders has not been reported. In this study, effective sleeping positions and a combination of sleep position determinants were evaluated with respect to their ability to reduce snoring and apnea. The positions evaluated included the following: cervical vertebrae support with head tilting (CVS-HT), scapula support (SS), and LP. A central composite design was applied for response surface analysis (RSA). Sixteen patients with mild or moderate positional sleep apnea and snoring who underwent polysomnography for two nights were evaluated. Based on an estimated RSA equation, LP (with a rotation of at least 30°) had the most dominant effect [ P  = 0.0057 for snoring rate, P  = 0.0319 for apnea–hypopnea index (AHI)]. In addition, the LP was found to interact with CVS-HT ( P  = 0.0423) for snoring rate and CVS-HT ( P  = 0.0310) and SS ( P  = 0.0265) for AHI. The optimal sleep position reduced mild snoring by more than 80% (i.e. snoring rate in the supine position was <20%) and the snoring rate was approximately zero with a 40° rotation. To achieve at least 80% reduction of AHI, LP and SS should be >30° and/or 20 mm respectively. To determine an effective sleep position, CVS-HT and SS, as well as the degree of the LP, should be concurrently considered in patients with positional sleep apnea or snoring.     

Are we missing a simple treatment for most adult sleep apnea patients? The avoidance of the supine sleep position

Obstructive sleep apnea (OSA) is a sleep disorder which has been gradually accepted as an important cause of increased morbidity and mortality. The treatment of moderate–severe OSA has improved dramatically since the introduction of continuous positive airway pressure (CPAP) devices; however, the adherence of patients to CPAP treatment is relatively low. Adherence appears to be even worse in patients with mild or asymptomatic OSA. The failure to identify and treat mildly symptomatic or asymptomatic OSA patients may be costly, as such patients comprise about 20% of the general adult population. OSA patients could be divided into positional and non‐positional patients. Positional patients show most of their breathing abnormalities while sleeping in the supine position. Simply, by sleeping in the lateral postures, they eliminate or reduce significantly the number of apneas and hypopneas. On the contrary, non‐positional patients suffer from breathing abnormalities in the supine and lateral postures, and as a consequence those are the most severe OSA patients for whom CPAP is the treatment of choice. In this paper we intend to argue that positional therapy, i.e. avoidance of the supine posture during sleep, could represent a valuable therapy mainly for mild–moderate OSA. Considering the fact that the vast majority of mild–moderate OSA patients are positional patients (between 65 and 87%), positional therapy may be a simple, cheap and effective solution for them. High‐quality research regarding this issue is needed to evaluate the real effectiveness of this mode of therapy.     

Snoring in normal young adults: prevalence in sleep stages and associated changes in oxygen saturation, heart rate, and breathing pattern

Six men and three women, asymptomatic light snorers ranging in age from 25-34 years, were studied during sleep to determine the prevalence of snoring in the different sleep stages, the associated changes in oxygen saturation (SaO2), heart rate (HR), and breathing frequency (f), and the associated breathing arrhythmias. Snoring was defined as a 1-minute epoch with more than 80% of the breaths associated with snores. Most of the snoring epochs as well as the apneas and hypopneas occurred during stage 2, mainly because it is the most prolonged sleep stage. The prevalence of snoring, however, normalized for differences in length of sleep stages, was highest in stages 3 and 4 but low in REM, whereas the converse was true for apneas and hypopneas. Snoring caused no change in the mean SaO2, mean HR, or f, as compared with nonsnoring periods in the same sleep stage. Continuous snoring in normal subjects can occur without significant O2 desaturation or breathing arrhythmia. Continuous snoring and breathing arrhythmia tended to occur together in a given subject but were unrelated in time, suggesting a different pathogenesis.     

Snoring sounds variability as a signature of obstructive sleep apnea

Snoring sounds vary significantly within and between snorers. In this study, the variation of snoring sounds and its association with obstructive sleep apnea (OSA) are quantified. Snoring sounds of 42 snorers with different degrees of obstructive sleep apnea and 15 non-OSA snorers were analyzed. The sounds were recorded by a microphone placed over the suprasternal notch of trachea, simultaneously with polysomnography (PSG) data over the entire night. We hypothesize that snoring sounds vary significantly within a subject depending on the level of obstruction, and thus the level of airflow. We also hypothesize that this variability is associated with the severity of OSA. For each individual, we extracted snoring sound segments from the respiratory recordings, and divided them into three classes: non-apneic, hypopneic, and post-apneic using their PSG information. Several features were extracted from the snoring sound segments, and compared using a nonparametric statistical test. The results show significant shift in the median of features among the snoring sound classes (p < 0.00001) of an individual. In contrast to hypopneic and post-apneic classes, the characteristics of snoring sounds did not vary significantly over time in non-apneic class. Therefore, we used the total variation norm of each subject to classify the participants as OSA and non-OSA snorers. The results showed 92.9% sensitivity, 100% specificity and 96.4% accuracy.     

Evaluation of a new simple treatment for positional sleep apnoea patients

Obstructive sleep apnoea syndrome is a common clinical problem. Positional sleep apnoea syndrome, defined as having a supine apnoea-hypopnoea index of twice or more compared to the apnoea-hypopnoea index in the other positions, occurs in 56% of obstructive sleep apnoea patients. A limited number of studies focus on decreasing the severity of sleep apnoea by influencing sleep position. In these studies an object was strapped to the back (tennis balls, squash balls, special vests), preventing patients from sleeping in the supine position. Frequently, this was not successful due to arousals while turning from one lateral position to the other, thereby disturbing sleep architecture and sleep quality. We developed a new neck-worn device which influences sleep position by offering a vibration when in supine position, without significantly reducing total sleep time. Thirty patients with positional sleep apnoea were included in this study. No side effects were reported. The mean apnoea-hypopnoea index dropped from 27.7 ± 2.4 to 12.8 ± 2.2. Seven patients developed an overall apnoea-hypopnoea index below 5 when using the device in ON modus. We expect that positional therapy with such a device can be applied as a single treatment in many patients with mild to moderate position-dependent obstructive sleep apnoea, while in patients with a more severe obstructive sleep apnoea such a device could be used in combination with other treatment modalities.     

Sleep problems and daytime somnolence in a German population-based sample of snoring school-aged children

Habitual snoring is associated with daytime symptoms like tiredness and behavioral problems. Its association with sleep problems is unclear. We aimed to assess associations between habitual snoring and sleep problems in primary school children. The design was a population-based cross-sectional study with a nested cohort study. The setting was twenty-seven primary schools in the city of Hannover, Germany. Habitual snoring and sleep problems were assessed in primary school children using an extended version of Gozal's sleep-disordered breathing questionnaire (n = 1144). Approximately 1 year later, parents of children reported to snore habitually (n = 114) and an equal number of children who snored never or occasionally were given the Sleep Disturbance Scale for Children, a validated questionnaire for the assessment of pediatric sleep problems. Snoring status was re-assessed using the initial questionnaire and children were then classified as long-term habitual snorers or ex-habitual snorers. An increasing prevalence of sleep problems was found with increasing snoring frequency for sleep-onset delay, night awakenings, and nightmares. Long-term habitual snorers were at significantly increased risk for sleep-wake transition disorders (e.g. rhythmic movements, hypnic jerks, sleeptalking, bruxism; odds ratio, 95% confidence interval: 12.0, 3.8-37.3), sleep hyperhidrosis (3.6, 1.2-10.8), disorders of arousal/nightmares (e.g. sleepwalking, sleep terrors, nightmares; 4.6, 1.3-15.6), and excessive somnolence (i.e. difficulty waking up, morning tiredness, daytime somnolence; 6.3, 2.2-17.8). Ex-habitual snorers were at increased risk for sleep-wake transition disorders (4.4, 1.4-14.2). Habitual snoring was associated with several sleep problems in our study. Long-term habitual snorers were more likely to have sleep problems than children who had stopped snoring spontaneously.     

Effect of sleep position and sleep stage on the collapsibility of the upper airways in patients with sleep apnea

Collapsibility of the upper airways has been identified as an important pathogenic factor in obstructive sleep apnea (OSA). Objective measures of collapsibility are pharyngeal critical pressure (Pcrit) and resistance of the upstream segment (Rus). To systematically determine the effects of sleep stage and body position we investigated 16 male subjects suffering from OSA. We compared the measures in light sleep, slow-wave sleep, REM sleep and supine vs. lateral positions. The pressure-flow relationship of the upper airways has been evaluated by simultaneous readings of maximal inspiratory airflow (Vimax) and nasal pressure (p-nCPAP). With two-factor repeated measures ANOVA on those 7 patients which had all 6 situations we found a significant influence of body position on Pcrit (p<0.05) whereas there was no significant influence of sleep stage and no significant interaction between body position and sleep stage. When comparing the body positions Pcrit was higher in the supine than in the lateral positions. During light sleep Pcrit decreased from 0.6 +/- 0.8 cm H2O (supine) to -2.2 +/- 3.6 cm H2O (lateral) (p<0.01), during slow-wave sleep Pcrit decreased from 0.3 +/- 1.4 cm H2O (supine) to -1.7 +/- 2.6 (lateral) (p<0.05) and during REM sleep it decreased from 1.2 +/- 1.5 cm H2O to -2.0 +/- 2.2 cm H2O (p<0.05). Changes in Rus revealed no body position nor sleep-stage dependence. Comparing the different body positions Rus was only significantly higher in the lateral position during REM sleep (p<0.05). The results indicate that collapsibility of the upper airways is not mediated by sleep stages but is strongly influenced by body position. As a consequence lower nCPAP pressure is needed during lateral positions compared to supine positions.     

Nasal steroids in snorers can decrease snoring frequency: a randomized placebo‐controlled crossover trial

Although it is anecdotally known that nasal obstruction is associated with snoring, it remains unknown whether the application of nasal steroids could decrease oral/oro‐nasal breathing and increase nasal breathing, and subsequently decrease snoring indices. This study evaluated the effect of nasal budesonide on breathing route pattern and snoring. Twenty‐four snorers were enrolled in a randomized, double‐blind, crossover trial of 1‐week treatment with nasal budesonide compared with 1‐week intervention with nasal placebo. At the start and end of each treatment period, patients underwent nasal resistance measurement and overnight polysomnography with concomitant measurement of breathing route pattern and snoring. Twelve patients were randomly assigned to a 1‐week treatment with nasal budesonide, followed by 2‐week washout period and a 1‐week intervention with the nasal placebo; and 12 patients were randomly assigned to a 1‐week intervention with nasal placebo, followed by 2‐week washout period and a 1‐week treatment with nasal budesonide. Nasal budesonide was associated with a decrease in oral/oro‐nasal breathing epochs and concomitant increase in nasal breathing epochs, decrease of snoring frequency by [median (interquartile range)] 15.8% (11.2–18.8%), and an increase of rapid eye movement sleep; snoring intensity decreased only in patients with increased baseline nasal resistance by 10.6% (6.8–14.3%). The change in nasal breathing epochs was inversely related to the change in snoring frequency (R_s = 0.503; P < 0.001). Nasal budesonide in snorers can increase nasal breathing epochs, modestly decrease snoring frequency and increase rapid eye movement sleep.     

Pattern of snoring in obstructive sleep apnea patients and in heavy snorers.

We measured respiratory mechanical characteristics during sleep in five heavy, nonapneic snorers (HS) and in five obstructive sleep apnea (OSA) patients. In two HS and in two OSA patients we obtained lateral pharyngeal cineradiographic images during sleep while snoring. Flow limitation preceded all snores in both HS and OSA. Pattern of snoring, hysteresis and temporal relationship between supraglottic pressure (Psg) and flow rate were different in HS and OSA. Maximal flow during snoring was less (p less than 0.05) in OSA (0.18 +/- 0.07 liter/second) than in HS (0.36 +/- 0.06 liter/second). Linear supraglottic resistance during inspiratory snoring was higher, though not significantly, in OSA patients (7.11 +/- 3.01 cm H2O/liter/second) than in HS (4.80 +/- 2.83 cm H2O/liter/second). We conclude that: 1) Snoring is characterized by high frequency oscillations of the soft palate, pharyngeal walls, epiglottis and tongue. 2) Flow limitation appears to be a sine qua non for snoring during sleep. 3) The pattern of snoring is different in OSA and HS. 4) Pharyngeal size during snoring is probably larger in HS than in OSA patients.     

Situational factors affecting sleep paralysis and associated hallucinations: position and timing effects

Sleep paralysis (SP) entails a period of paralysis upon waking or falling asleep and is often accompanied by terrifying hallucinations. Two situational conditions for sleep paralysis, body position (supine, prone, and left or right lateral decubitus) and timing (beginning, middle, or end of sleep), were investigated in two studies involving 6730 subjects, including 4699 SP experients. A greater number of individuals reported SP in the supine position than all other positions combined. The supine position was also 3-4 times more common during SP than when normally falling asleep. The supine position during SP was reported to be more prevalent at the middle and end of sleep than at the beginning suggesting that the SP episodes at the later times might arise from brief microarousals during REM, possibly induced by apnea. Reported frequency of SP was also greater among those consistently reporting episodes at the beginning and middle of sleep than among those reporting episodes when waking up at the end of sleep. The effects of position and timing of SP on the nature of hallucinations that accompany SP were also examined. Modest effects were found for SP timing, but not body position, and the reported intensity of hallucinations and fear during SP. Thus, body position and timing of SP episodes appear to affect both the incidence and, to a lesser extent, the quality of the SP experience.     

Can snoring induce or worsen obstructive sleep apnea?

Snoring and sleep apneas are breathing disorders intimately associated during sleep. Most snorers are ‘simple’ or ‘nonapneic’, as the prevalence of snoring is much higher than that of sleep apneas. The vibrations transmitted to the pharyngeal structures by snoring span a large range of frequencies, while the energy transmitted may reach high values. A deleterious effect of these vibrations can therefore be considered.In 1983 a group of investigators from Bologna described five cases of heavy snorers of increasing severity, suggesting that they correspond to the natural history of ‘heavy snorers’ disease'. The present article reviews the data published since 1983 in favor of this hypothesis: anatomic lesions of the upper airway mucosa, pharyngeal muscles and nerves, and clinical observations in snorers. The conclusion stresses the absence of ultimate proof in favor of this attractive hypothesis: we lack the demonstration of a significant increase of the incidence of sleep apnea in a group of nonapneic snorers in a longitudinal follow-up study.     

The prevalence of restless sleep disorder among a clinical sample of children and adolescents referred to a sleep centre

Restless sleep disorder (RSD) is a newly described sleep disorder in children characterized by large body movements and repositioning that lasts all night with at least five body movements per hour and a significant impact on daytime behaviours. The authors have previously identified and described the syndrome and compared the sleep parameters and sleep‐related movements to those in children with restless legs syndrome, normal controls and snorers. The current study is a retrospective review of the sleep diagnosis in 300 consecutive children seen and evaluated in a single sleep disorders centre; 252 children underwent polysomnography, as clinically indicated, to identify the proper diagnosis. The current research estimates the prevalence of RSD in a sleep clinical setting to be 7.7% and compares it to the prevalence of other common sleep disorders in the same setting. Another important addition to the literature is the fact that RSD can coexist with other sleep disorders, such as habitual snoring and parasomnia, without confounding the diagnosis.     

Snoring & sleep apnea: a population study in Italian women

The aim of this cross-sectional study was to evaluate the prevalence of sleep-disordered breathing by means of a validated portable instrument (MESAM IV) and to investigate the relationship between snoring and sleep apnea in a sample of Italian middle-aged female population. We randomly chose 750 subjects aged 40 to 65 years and 365 agreed to participate to the study. In this group, 19.7% of subjects were every-night snorers according to the questionnaire; when recorded, 54.2% snored for more than 10% of the night, and 7.1% for more than 50% of the night. Sleep apnea was also common: 10.7% of subjects had a respiratory disturbances per hour (RDI) between 5 and 9, 7.7% an RDI between 10 and 19, and 2.2% had an RDI > or =20. Snoring percentage and RDI were significantly correlated. However, 50% of subjects who snored for more than half the night had no evidence of sleep apnea. Snoring amount >50% resulted influenced by body mass index, while RDI>10 was influenced by neck diameter. We concluded that in middle-aged women, both snoring and sleep apnea are very common. A high percentage of snoring is not essential for the occurrence of sleep apnea, nor it necessarily indicates the presence of sleep apnea.     

Konservative Therapie beim Schnarchen

Although snoring is a frequent issue, snorers without concomitant sleep apnea rarely suffer from clinical symptoms. Therefore, the need for therapy only arises when bed partners feel bothered or local discomfort like xerostomia appears. It is unclear if snoring is a pathological problem. Therapeutic approaches comprise weight loss, positional and local therapy as well as neurostimulation. Moreover, patients with obstructive snoring might use mandibular advancement devices or continuous positive airway pressure therapy. Until now, there is no general therapeutic strategy for snorers without sleep apnea due to an insufficient number of clinical trials addressing therapy efficacy in those patients.     

Ischaemic stroke, snoring and obstructive sleep apnoea

SUMMARY  Ischaemic stroke occurs most often during the morning hours before noon. In recent studies the peak time of onset has been between 10.00 and 12.00 hours. Snoring every night or almost every night (habitual snoring) is in relation with ischaemic stroke. Snoring occasionally, on the contrary, is not significantly related with stroke. Habitual snoring is the most typical sign of obstructive sleep apnoea syndrome and it is strongly associated with being overweight. Other possible pathophysiological factors that are in relation with habitual snoring, obstructive sleep apnoea and stroke include arterial hypertension, changes in fibrinolytic activity, adult onset diabetes and smoking. It remains to be seen whether nightly occurring partial upper airway obstruction (habitual snoring) with intrathoracic pressure changes is an independent risk factor of ischaemic stroke. There is recent evidence that everything cannot be explained by other known risk factors.     

Obstructive sleep apnoea in adults: body postures and weight changes interactions

The aim of this work was to study the relationship between changes of body posture dominance and changes of body weight overtime in adults with obstructive sleep apnoea. The participants were 112 non-treated adults with obstructive sleep apnoea who underwent two polysomnographic evaluations at our Sleep Disorders Unit during an average of 6.2years interval. Positional patients - having most of their breathing abnormalities in the supine posture and who became non-positional patients - had a significant gain in weight and a significant increase in apnoea-hypopnoea index, mainly in lateral apnoea-hypopnoea index. On the contrary, non-positional patients who became positional patients had a significant decrease in weight (but less than the increase in weight of positional patients who became non-positional patients) and showed a significant improvement in apnoea-hypopnoea index, again mainly in lateral apnoea-hypopnoea index. These non-positional patients who became positional patients initially had a less severe disease, as judged by apnoea-hypopnoea index, lateral apnoea-hypopnoea index and minimum SaO(2) during non-rapid eye movement sleep, and were less obese than non-positional patients who remained non-positional patients. The later were the patients who showed initially the worst disease and were more obese than the rest of the patients, and their condition did not change significantly over time. Non-positional patients who converted to positional patients showed a decrease in body weight and improvement of obstructive sleep apnoea, while positional patients who converted to non-positional patients showed an increase in body weight and worsening of obstructive sleep apnoea. It appears that weight changes have a modulatory effect on positional dominance, and lateral apnoea-hypopnoea index appears to be a sensitive parameter of these changes.     

Influence of sleep posture on response to oral appliance therapy for sleep apnea syndrome

STUDY OBJECTIVE: This study evaluated the effect of sleep posture on oral appliance therapy to elucidate the interindividual difference of response to the device. DESIGN: Seventy-two unselected patients with sleep apnea syndrome were studied polysomnographically before and after insertion of the individually fabricated and adjusted device. Sleep positions were measured using a body position sensor. The patients were classified into three groups; supine, lateral and prone groups, according to the position in which apneas were most frequently observed. SETTING: N/A. PATIENTS OR PARTICIPANTs: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The mean apnea-hypopnea index (AHI) of all patients before treatment [43.0+/-25.6 (SD)] was significantly (p<0.0001) decreased after insertion of the appliance (21.6+/-18.3). The device decreased the mean AHI significantly from 29.8 to 11.3 in the supine position and 5.5 to 1.6 in the prone position, and increased, but not significantly, from 7.7 to 8.7 in the lateral posture. The supine (n=44) and prone (n=13) groups showed significant reduction of AHI with the oral appliance, while the lateral group (n=15) revealed only a slight decrease, although not significantly. Responders defined by AHI<10 accounted for 61.4% in the supine group, 0% in the lateral group and 84.6% in the prone group. Responders defined by a 50% drop in AHI accounted for 84.1%, 6.7%, and 46.7%, respectively. CONCLUSIONS: The effectiveness of oral appliance therapy is greatly influenced by sleep posture. Sleep posture recorded by polysomnography may be useful to predict the future success or failure of the device.