Sleep Posture Research Articles

CORRELATION OF UNILATERAL UROLITHIASIS WITH SLEEP POSTURE

CORRELATION OF UNILATERAL UROLITHIASIS WITH SLEEP POSTURE

Changes in EEG power spectra and behavioral states in rats exposed to the acetylcholinesterase inhibitor chlorpyrifos and muscarinic agonist oxotremorine

Organophosphates (OPs) inhibit acetylcholinesterase (AChE) activity causing cholinergic stimulation in the central nervous system (CNS). Cholinergic systems are crucial in electroencephalogram (EEG) generation and regulation of behavior; however, little is known about how OP exposure affects the EEG and behavioral states. We recorded EEG, core temperature and motor activity before and after exposure to the OP pesticide chlorpyrifos (CHP) in adult female rats implanted with telemetric transmitters. The recording and reference electrodes were placed in the occipital and frontal bones, respectively. The animals received CHP, 25 mg/kg, p.o., or oxotremorine (OX), 0.2 mg/kg, s.c. CHP led to a significant increase in delta (0.1–3.5 Hz), slow theta (4–6.5 Hz), gamma 2 (35.5–50 Hz), reduction in fast theta (7–8.5 Hz), alpha/sigma (9–14 Hz), beta 1 (14.5–24 Hz), beta 2 (24.5–30 Hz) and gamma 1 (30.5–35 Hz) powers, slowing of peak frequencies in 1–9 Hz range, hypothermia and decrease in motor activity. The drop in 7–14 Hz was associated with cholinergic suppression of sleep spindles. Changes in behavioral state were characterized by dramatic diminution of sleep postures and exploring activity and prolongation of quiet waking. There was recovery in all bands in spite of continued inhibition of AChE activity [44,45] in rats exposed to CHP. OX-induced EEG and behavioral alterations were similar to CHP except there was no increase in delta and the onset and recovery were more rapid. We did not find a correlation between the EEG and core temperature alterations. Overall, changes in EEG (except in delta band) and behavior following CHP were attributable to muscarinic stimulation. Cortical arousal together with increased quiet waking and decreased sleep after CHP occurred independently from inhibition of motor activity and lowering of core temperature.

Upright body position and weight loss improve respiratory mechanics and daytime oxygenation in obese patients with obstructive sleep apnoea.

To determine whether upright body position and weight loss would improve daytime gas exchange in moderately obese patients with obstructive sleep apnoea (OSAS), 13 patients with mild or moderate OSAS were studied before and after weight loss. Pulmonary function tests, arterial blood gases and respiratory gas analysis were measured prior to and after a very low calorie diet (VLCD) period of six weeks. Arterial blood gases were measured in supine and standing positions and closing volume in supine and sitting positions before and after weight loss. In the upright position, there was a significant increase in PaO2 (P<0.005) accompanied by a significant decrease in alveolar-arterial PO2 difference (P<0.005) and closing volume (P<0.05). The median weight loss was 11 kg (range 5-18). The number of desaturation episodes (four percentage units or more per hour during sleep) (ODI4) decreased (P<0.01) after weight loss. The change in PaO2 with weight loss correlated with the decrease in ODI4 (r=0.73, P<0.01). The increase in expiratory reserve volume (ERV) was closely related to the amount of weight lost (r=0.895, P<0.01). The results indicate that weight loss and upright body position improved daytime respiratory mechanics and gas exchange in obese patients with OSAS. The findings suggest that obesity plays an important role in the pathogenesis of daytime gas exchange disturbances in obese OSAS patients. The adoption of a more upright sleep posture might improve nocturnal oxygenation in obese patients with OSAS.

Posterior plagiocephaly: proactive conservative management

SUMMARY.The pathology, diagnosis and management of posterior plagiocephaly remains highly controversial. While the rationale for surgical management of true lambdoid synostosis is undisputed, opinions vary greatly on how to manage severe, unresolving, non-synostotic cases. We reviewed 39 cases of posterior plagiocephaly, 37 of which were treated conservatively. Of these, 34 patients had a significant improvement over the following year with sleep posture modification and/or physiotherapy. While only eight cases returned to complete normality, the remainder had deformities that were deemed mild by both mothers and surgeons, and did not merit surgery. Defining recalcitrant cases remains elusive as standard imaging is often unhelpful. While 3-D CT offers a much more accurate diagnosis of true lambdoid synostosis with bony union and allows objective assessment of the deformity, serial scans involve radiation doses that are difficult to justify. Clinical follow-up is the only reliable method at present.

The effect of body posture on sleep-related breathing disorders: facts and therapeutic implications.

The aggravating effect of the supine body position on breathing abnormalities during sleep was recognized from the earliest studies on sleep breathing disorders. Most of the anatomical and physiological correlates of this phenomenon appear to be due to the effect of gravity on the upper airway. Although few articles have been published on this topic, it has been shown in a large population of obstructive sleep apnoea (OSA) patients that more than half of them are Positional Patients, i.e. they have at least twice as many apnoeas/hypopnoeas during sleep in the supine posture as in the lateral position. This positional phenomenon is influenced by factors such as Respiratory Disturbances Index (RDI), Body Mass Index (BMI), age and sleep stages. The sleep supine posture not only increases the frequency of the abnormal breathing events but also their severity. This sleep posture also has a detrimental effect on snoring, as well as on the optimal CPAP pressure. Positional Therapy, i.e. the avoidance of the supine posture during sleep, is a simple behavioural therapy for many mild to moderate OSA patients. Unfortunately, only a few studies, including only a few patients, have investigated this form of therapy. Although the results of these studies are promising, the lack of a reliable long-term evaluation of its efficacy is perhaps an important reason why this form of therapy has not been widely accepted. Since mild to moderate OSA patients are the majority of the OSA patients and since without treatment, a large percentage of them will develop a more severe form of the disease, a thorough evaluation with a major emphasis on the long-term effectiveness of this form of therapy is urgently needed.

睡眠と姿勢

睡眠と姿勢

Effects of sleep posture on upper airway stability in patients with obstructive sleep apnea.

Changes in sleep posture have been shown to improve obstructive sleep apnea (OSA). To investigate the mechanisms by which this occurs we assessed upper airway stability in eight patients with severe OSA in three postures (supine, elevated to 30 degrees, and lateral). We used a specially adapted nasal continuous positive airway pressure (nCPAP) mask to measure upper airway closing pressure (UACP) and upper airway opening pressure (UAOP) during non-REM sleep. Statistical comparisons were made between postures using ANOVA for repeated measures. Elevation resulted in a less collapsible airway compared with both the supine and lateral positions (mean UACP: 30 degrees elevation -4.0 +/- 3.2 compared with supine 0.3 +/- 2.4 cm H2O, p < 0.05 and; lateral -1.1 +/- 2.2 cm H2O, p < 0.05). Supine UACP and lateral UACP were not significantly different. Elevation or lateral positioning produced a 50% reduction in mean UAOP (supine 10.4 +/- 3.5 cm H2O compared with 30 degrees elevation 5.3 +/- 2.1, p < 0.05; and lateral 5.5 +/- 2.1 cm H2O, p < 0.05). We conclude that in severely affected OSA patients upper body elevation, and to a lesser extent lateral positioning, significantly improve upper airway stability during sleep, and may allow therapeutic levels of nCPAP to be substantially reduced.

The Influence of the Sleeping Posture on Jaw Muscle EMGs of Young Children during Voluntary Jaw Clenching

The Influence of the Sleeping Posture on Jaw Muscle EMGs of Young Children during Voluntary Jaw Clenching

Management of simple snoring, upper airway resistance syndrome, and moderate sleep apnea syndrome.

The spectrum of respiratory sleep disorders has been extended in the last years to include conditions that are less well defined than severe obstructive sleep apnea (OSA). Moderate OSA, snoring, and upper airway resistance syndrome (UARS) represent three conditions in which there are still unresolved pathophysiological, epidemiological, and clinical questions. Therefore, the therapeutic approach remains unclear. We have tried to define these entities and to review the respective indications and efficacy of pharmacological treatment, weight loss, sleep posture, oral appliances, upper airway surgery, and finally, continuous positive airway pressure (CPAP). From these data, we also aim to define strategies of treatment for moderate OSA, snoring, and UARS. However, these conditions are likely to be particularly appropriate for randomized trials comparing different modalities of treatment that may be the only way to validate these treatment strategies.

A study of sleep in the European blackbird

Sleep states in the blackbird, Turdus merula, were determined by recording the electroencephalogram (EEG), electrooculogram (EOG), electromyogram (EMG), and heart rate (HR), and from behavioral observations and responses to auditory stimulation by natural calls. The presence of changes in slow wave activity was determined from the power spectra of the EEG. Spectral power density in the 0.5–4.0 Hz band during slow wave sleep (SWS) attained highest values in the first part of the night, then declined. This trend in EEG spectra, which occurred across the night, probably reflects a homeostatic process strikingly similar to that observed in mammals. The reactivity to natural calls during SWS episodes also decreased across the night. Episodes of interhemispheric EEG asymmetry, which typically lasted from 2 to 4 s, occurred when birds displayed the front sleep posture and they constituted 140–200 s of each night. Unihemispheric sleep episodes probably result from unilateral activation of the visual system, and they could be considered as an evolutionary adaptation. HR was highest in wakefulness and lower in sleep but, due to large variability, reliable discrimination between sleep and wakefulness could not be made. Comparison of the blackbird's behavior during 4 different nights revealed a strong effect of the first night on sleeping behavior. A significant reduction in back sleep posture occurred during the baseline night, when lead wires were connected.

Sleeping positions and dental arch dimensions in children with suspected obstructive sleep apnea syndrome.

The present paper analyzed the association between children's sleeping positions and dental arch morphology. The sleeping patterns of 27 children, aged 3 to 10 yr, suspected of having the obstructive sleep apnea syndrome (OSAS) were studied by polysomnography (PSG) and videotape recordings under laboratory conditions. The PSG recordings were used to calculate the apnea index (AI) and the relative time spent sleeping on the back, and the videotapes to categorize distinctly different sleep and head postures. Plaster casts were made for the assessment of dental arch morphology. Sleeping predominantly on one's back, was associated with a reduced maxillary intercanine width, while prolonged head extension during sleep correlated inversely with the overjet. The subjects with the highest AI scores (> 4) had larger dental arches. We suggest that sleeping on the back causes a more posterior tongue position, reducing its moulding effect on the anterior dental arch. As nasopharyngeal airway obstruction in OSAS-patients might trigger an anterior tongue position to secure a free airway passage, there will be increased lingual pressure on the dental arches, leading to their dimensional increase.

Sleep apnoea in patients with quadriplegia.

This study was undertaken to establish the prevalence of, and the factors contributing towards, sleep disordered breathing in patients with quadriplegia. Forty representative quadriplegic patients (time since injury > 6 months, injury level C8 and above, Frankel category A, B, or C; mean (SE) age 35.0 (1.7) years) had home sleep studies in which EEG, EOG, submental EMG, body movement, nasal airflow, respiratory effort, and pulse oximetry (SpO2) were measured. Patients reporting post traumatic amnesia of > 24 hours, drug or alcohol abuse or other major medical illness were excluded from the study. A questionnaire on medications and sleep was administered and supine blood pressure, awake SpO2, spirometric values, height, and neck circumference were measured. A pattern of sustained hypoventilation was not observed in any of the patients. Sleep apnoeas and hypopnoeas were, however, common. Eleven patients (27.5%) had a respiratory disturbance index (RDI, apnoeas plus hypopnoeas per hour of sleep) of > or = 15, with nadir SpO2 ranging from 49% to 95%. Twelve of the 40 (30%) had an apnoea index (AI) of > or = 5 and, of these, nine (75%) had predominantly obstructive apnoeas-that is, > 80% of apnoeas were obstructive or mixed. This represents a prevalence of sleep disordered breathing more than twice that observed in normal populations. For the study population RDI correlated with systolic and diastolic blood pressure and neck circumference. RDI was higher in patients who slept supine compared with those in other postures. Daytime sleepiness was a common complaint in the study population and sleep architecture was considerably disturbed with decreased REM sleep and increased stage 1 non-REM sleep. Sleep disordered breathing is common in quadriplegic patients and sleep disturbance is significant. The predominant type of apnoea is obstructive. As with non-quadriplegic patients with sleep apnoea, sleep disordered breathing in quadriplegics is associated with increased neck circumference and the supine sleep posture.

Pseudo-hypersomnia and pre-sleep behaviour with bilateral paramedian thalamic lesions

The sleep/wake status of three patients with bilateral lesions involving the paramedian thalamic regions was investigated. Long-term monitoring with infrared video camera and polygraphy were performed. In spite of presenting a behavioural aspect of sleep with sleep posture, eyes closed and lack of activity for 15-17 h per day, these subjects did not develop the normal non-rapid eye movement (NREM) and rapid eye movement (REM) sleep states during the daytime. The EEG indicated presence of a mixture of low amplitude, irregular, diffuse theta and alpha range frequencies during hours associated with this 'sleep-like' behaviour. Multiple sleep latency tests performed some time after the acute insult gave varying results, but while stage 1 NREM sleep might have been noted for three to four epochs, other states of sleep never appeared. Patients were apathetic and 'drowsy' but could develop sleep only during the normal circadian period for sleep, i.e. during the night. Even several years later, in one of the subjects in whom follow-up recordings were obtained, apathetic behaviour and sleep 'posturing' were present during much of the day, even though the subject, if requested, could perform tasks adequately all day long. Subjects with such lesions do not present a 'hypersomnia' but a 'de-arousal' or 'subwakefulness' with inability to develop sleep outside the normal circadian boundaries for its appearance. However, these subjects, at least initially, also lacked full wakefulness. They have a behavioural impairment with a compulsive sleep posture and are left in the transition between wakefulness and sleep.

Relations Between Sleep Stage, Posture and Effective Nasal CPAP Levels in OSA

A retrospective analysis of positional data from 100 male patients with obstructive sleep apnea (OSA) was conducted to determine whether or not 1) the degree of positional dependency was similar in rapid eye movement (REM) compared to non-REM (NREM) sleep, 2) positional dependency correlated with effective levels of nasal continuous positive airway pressure (CPAP) and 3) patients with positional OSA preferentially avoided sleeping in the supine position. The apnea-hypopnea index (AHI) was scored separately for sleep state (NREM and REM) and for posture [off back (AHI-O) and on back (AHI-B)]. The ratio of AHI-O/AHI-B was used to define positional OSA as AHI-O/AHI-B less than or equal to 0.50 (P group) and nonpositional OSA as 0.50 less than AHI-O/AHI-B (NP group). A group of 31 patients who had sufficient sleep time in NREM and REM sleep in both sleep postures was selected. In this group 9 out of 22 subjects who showed positional dependency during NREM sleep became nonpositional during REM sleep (0.05 less than p less than 0.10). The mean effective nasal CPAP level was slightly, but significantly, lower in the P group than in the NP group (8.0 versus 9.1 cm H2O; p less than 0.05). In addition, a correlation between AHI and effective nasal CPAP levels was found (r = 0.491; p = 0.0001). The P group had less supine sleep time (SST) than the NP group (32% versus 45% of total sleep; p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

A Comparative Study of Treatments for Positional Sleep Apnea

Sixty male patients all with apnea plus hypopnea indices (A + HI) above 12.5, who met a criterion of positionality by having two or more times the rate of these events during supine sleep in comparison to their lateral sleep rate, were randomly assigned to one of four treatments for 8 weeks. All were restudied for two nights, one with and one without treatment devices. On treatment more than half the patients in each group reduced their A + HI to within normal limits and a third remained WNL without the use of devices. Half of those trained to sleep in the lateral position with the help of an alarm maintained this learning without the alarm as did half of those who were encouraged to learn this sleep posture on their own. There is an additive effect for the positional patient from wearing a tongue retaining device (TRD) if they continue to sleep in the supine position. Factors associated with successful treatment include overall severity, severity in the lateral position, weight, weight change, nasal patency and motivation to help their condition.

The Effects of Sleep Posture and Sleep Stage on Apnea Frequency

The Apnea Plus Hypopnea Index (A + HI) of 60 male positional sleep apneics was analyzed by sleep stage to determine if positional differences are limited to NREM sleep. Differences in apnea severity by sleep position were found to persist in REM sleep and to be of equal extent to those differences found in NREM sleep, despite the fact that there is also a significant increase in the frequency of apneic events associated with REM sleep. The positional effect persists in REM sleep, making treatments to control sleep posture a viable option.

Oxytocin inhibits male sexual behavior in prairie voles

Intracerebroventricular (ICV) injection of oxytocin (300 ng) produced an immediate cessation in sexual behavior in sexually active male prairie voles ( Microtus ochrogaster). Other social behaviors including social contact, aggression, and autogrooming were not significantly affected by oxytocin, but males that received oxytocin ICV, versus injections that missed the ventricles, showed more sleep postures. Sexual behavior remained inhibited for at least 24 hours and was not activated in tests with a novel receptive female. Sexual and social were not significantly altered in animals in which the oxytocin injection missed the ventricles or in saline-treated males. These findings are consistent with the hypothesis that oxytocin plays a role in sexual satiety.

Sleep postures and power spectrum analysis of the EEG of the rat

An analysis of the relation between sleep postures and EEG power spectrum of young, adult and old male rats was performed. Three postures were distinguished: stretched, curved and curled up. A 5 minutes period of any posture was analyzed. The sleep data were gathered of the first two hours of the sleep period. The analysis revealed that the overall power of a curled up posture was less than that of two other sleep postures. Determination of a relation between an EEG measurement and sleep postures is promising.

Sleep-site fidelity in two Puerto Rican lizards

Observations on the sleep behaviour of the brown anole, Anolis gundlachi, and the crested anole, Anolis cristatellus, were conducted at two ecologically distinct sites on the island of Puerto Rico. Lizards returned nightly to specific sleep locations, and for at least 5 consecutive nights, up to 98% returned to within 1 m of their initial night's sleep site. Additionally, 55% of the A. gundlachi and 21% of the A. cristatellus returned to within 10 cm of the original night's sleep site. Daytime activity ranges were significantly greater than nightly variation in sleep-site location. Additional data were collected on (1) sleep posture and body dimensional plane (2) sleep-site height, and (3) the type of vegetation used for sleep sites (e.g. broad leafed plants versus narrow leafed plants etc.). Lizards selected sleep sites in proportion to the plant type available in the respective habitat. Sleep-site height was positively correlated with lizard size, and the modal pattern of sleep posture included a snout direction toward the stem of the leaf and the head above or aligned with the horizontal body plane. The consistent selection of a site near the previous night's location suggests that lizards have reserved a specific area of their home range for sleep. A survey of nocturnal predators and observations of a predatory event on a lizard displaced from its sleep site suggest that immobilization on the foliage surface is an adaptive strategy for avoiding predation.

The sleep apnea syndrome. Part II: Treatment

An increase in the number of obstructive sleep apnea patients has brought a paralleled demand for timely and effective treatment. Conservative measures to maintain airway patency during sleep include weight loss, lateral decubitus sleep posture, drug therapy, nasal continuous positive airway pressure, and the use of intraoral prostheses. Surgical measures are used to correct gross anatomic defects that cause or contribute to obstruction, remove redundant tissues (uvulopalatopharyngoplasty), or provide an airway below the suspected area of obstruction (tracheostomy). Part II of this article examines the rationale, benefits, disadvantages, and potential complications of each modality of treatment.