Biomedical subjects

S Ancoli-Israel

Publications and source records attributed to S Ancoli-Israel.

At least 55 records · Page 3Linked to original sources

PubMed1998

The effects of hypoxia and sleep apnea on isoproterenol sensitivity.

STUDY OBJECTIVES: To determine the effects of both apnea and hypoxia on beta-adrenergic receptor sensitivity. DESIGN: Cross-sectional study. SETTING: A clinical research center. PATIENTS: Forty-five normotensive and hypertensive sleep apnea patients (respiratory disturbance index >20) and non-apneic controls. MEASUREMENTS AND RESULTS: The chronotropic 25 dose (CD25), an in vivo measure of beta-adrenergic receptor sensitivity derived from the heart rate response to a graded infusion of isoproterenol, was determined while subjects breathed either a normoxic (21% O2, 79% N2) or a hypoxic (15% O2, 85% N2) gas mixture. Under normoxic conditions, apnea patients showed a significantly higher CD25 (lower beta-adrenergic receptor sensitivity) as compared to controls (5.9 microg, SD=2.1 versus 4.6 microg, SD=1.2, respectively; p=0.018). In response to hypoxia, apnea patients showed no change in CD25, while controls showed a significant increase in CD25 (beta-adrenergic receptor desensitization) (p=0.002), to a value comparable to the apneics' (5.6 microg, SD=2.0). CONCLUSION: The in vivo finding of reduced beta-adrenergic receptor sensitivity in sleep apnea patients is consistent with previous in vitro assessments of the beta-adrenergic receptor. The finding that apnea patients do not respond to hypoxia with a further receptor desensitization suggests that sleep apnea patients may have reached a threshold effect of hypoxia on the beta-adrenergic receptor. These findings may be relevant to the greater incidence of hypertension seen in patients with sleep apnea syndrome.

Adrenergic beta-Agonists↗

PubMed1998

Hourly profiles of sleep and wakefulness in severely versus mild-moderately demented nursing home patients.

The purpose of the current study was to examine differences in hour-by-hour sleep/wakefulness profiles between severely and mild-moderately demented patients, and to assess how many elderly patients remain almost fully asleep or nearly fully awake in each hour of a 24-hour period. Sleep/wakefulness patterns of 67 demented nursing home residents (mean age = 85.7 years) were recorded using Actillume recorders. One 24-hour period was used, and numbers of minutes spent asleep or awake were computed for every hour. There were 46 severely demented patients, and 21 mild-moderately demented patients. The amount of sleep and wakefulness recorded for each hour was compared between the two groups. In addition, the frequencies of patients who remained asleep for more than 90% of each hour, and of those who sustained wakefulness for more than 90% of each hour were computed for every hour, and comparisons were again made between the two groups. Multivariate analysis of variance showed a significant effect of dementia group on the percent of sleep/wakefulness over 24 hours (p = 0.028). Subsequent t-tests performed separately for each hour revealed significant differences between the two dementia groups in 13 out of the 24 hours. Significant differences in the frequencies of patients asleep > 90% or awake > 90% of each hour were centered around the early night and early morning hours. Patients with mild-moderate dementia showed a disproportionate amount of wakefulness during the night, whereas, in addition, patients with severe dementia showed a disproportionate amount of sleepiness during the day. With the progression of dementia, both the capacity to maintain sleep and the capacity to maintain wakefulness are impaired, and result in complete fragmentation of sleep/wakefulness during the night and day.

Activity Cycles↗

PubMed1997

Identification and treatment of sleep problems in the elderly.

For many adults, changes in sleep occur with aging. An estimated 15 million elderly, or 50% of older Americans, experience some sleep problem. The elderly complain that their sleep is more fragmented and that as they have gotten older, they experience more daytime sleepiness. Laboratory studies have confirmed these complaints. Research has shown that it is not the need for sleep that decreases with age, but rather the ability to sleep. Circadian rhythm disturbances, sleep disorders such as sleep disordered breathing and periodic movements in sleep, medical illness, medication use, and impaired cognitive functioning all contribute to poor sleep and decreased daytime alertness. In institutionalized elderly, sleep is even more disturbed and disrupted. With careful assessment, many of these problems can be addressed and treated, and sometimes cured.

Journal Article↗

PubMed1997

Use of wrist activity for monitoring sleep/wake in demented nursing-home patients.

Actigraphy is applicable for studying sleep in populations who are unable to tolerate traditional sleep-recording techniques, such as nursing-home patients who are infirm and demented. This study examined whether actigraphy can accurately reflect sleep/wake activity in this population by testing the reliability of a wrist-activity monitor, the Actillume, against traditional sleep measurements and against observations of nursing-home patients. Data from the Actillume are presented as two variables, the sum (total of all activity movements within the prescribed epoch) and the maximum activity (the largest or maximum movement recorded during the prescribed epoch), and by electroencephalogram (EEG). One difficulty in making comparisons was that the EEG records showed diffuse slowing, making it extremely difficult to score sleep/wake activity and making it difficult to use the EEG as a "gold standard". Nevertheless, the correlation for total sleep time from EEG and Actillume was r = 0.91 (p < 0.001) for sum activity and r = 0.81 for maximum activity (p < 0.005). Correlations for percent sleep were r = 0.78 (p < 0.01) for maximum activity and r = 0.61 for sum activity. The comparison of sleep/wake determined by the Actillume vs. observations resulted in a sensitivity of 87% and specificity of 90%. We conclude that the Actillume is the most feasible technique for studying sleep and wake activity in demented nursing-home patients.

Aged↗

PubMed1997

Prevalence of sleep-disordered breathing in ages 40-64 years: a population-based survey.

Previous research has offered widely varying prevalence estimates for sleep apnea in the population, leaving uncertain which breathing patterns are abnormal. To explore the distribution of sleep apnea in the population and its co-morbidities, random telephone dialing was used between 1990 and 1994 to recruit subjects for a prevalence survey of sleep-disordered breathing in San Diego adults. Events from which blood oxygen desaturations > or = 4% resulted were monitored with home recording instruments, usually for three consecutive nights. Among 190 women ages 40-64 years, a median of 4.3 desaturation events per hour of sleep were observed. A higher median of 6.7 events per hour was observed among 165 men. Frequencies were much higher among members of minority groups, leading to a standard estimate that 16.3% of U.S. Hispanics and racial minorities have > or = 20 events/hour as compared to 4.9% of non-Hispanic Whites ages 40-64. Obesity indicated by body-mass index was the most important demographic predictor of sleep-disordered breathing, followed by age, male gender, and ethnicity. Quality of well-being was not significantly impaired in subjects with more respiratory events; however, there was some increase in blood pressure and wake-within-sleep associated with sleep-disordered breathing. This survey indicates that sleep-disordered breathing is more common, especially among minorities, than had been previously believed, but less co-morbidity may be associated.

Adult↗

PubMed1997

Sleep apnea, norepinephrine-release rate, and daytime hypertension.

Patients with obstructive sleep apnea (OSA) are often hypertensive, and both apneics and hypertensives are reported to have increased sympathetic nerve activity. We measured plasma norepinephrine (NE) levels, clearance, and release rate among 65 subjects who breathed room air, a hypoxic gas mixture, and the hypoxic mixture combined with intermittent breath holding. Apneics' plasma NE across all three breathing conditions was 307 pg/ml compared with the non-apneics' level of 248 pg/ml (p = 0.017). NE clearance increased from 3.2 l/minute to 3.9 l/minute when subjects breathed a hypoxic gas mixture (p < 0.001). NE clearance was similar among normal controls, apneics, and hypertensives. The rate at which NE was released from sympathetic nerves into the bloodstream was higher among hypertensives but not among apneics while subjects breathed room air. Hypoxia increased the NE-release rate from 892 ng/minute to 1,042 ng/minute (p < 0.001) and increased the NE-release rate more among apneics than non-apneics (p < 0.001). The NE-release rate response to hypoxia and breath holding differed between hypertensives and normotensives (p < 0.001) and between apneics and non-apneics (p < 0.001). Normotensive apneics had the largest increase in NE release during hypoxia. Like other investigators, we found that plasma NE levels were increased among apneics. Calculation of NE-release rate and correction for blood pressure status revealed a more complex situation. Apneics breathing room air had a normal NE-release rate; any increase in sympathetic neuronal NE release could be attributed to apneics who were also hypertensive. However, apneics had a greater NE response to hypoxia. These results suggest that apneics are susceptible to transient increases in sympathetic nervous activity and that hypertensive apneics maintain increased sympathetic nervous release of NE in the daytime.

Adult↗

PubMed1997

Sympathetic nervous system alterations in sleep apnea. The relative importance of respiratory disturbance, hypoxia, and sleep quality.

Numerous alterations in the sympathetic nervous system have been reported in patients with obstructive sleep apnea. It is unclear whether such alterations can be attributed to the respiratory disturbance itself, the resulting hypoxia, or disruption of sleep. We examined urinary norepinephrine levels in 45 individuals with varying amounts of respiratory disturbance and sleep disruption. All were of similar age (40 to 60 years) and body weight (100 to 160% ideal body weight), and all were free from antihypertensive medications that could influence norepinephrine levels. Twenty-four-hour urinary norepinephrine levels were correlated with respiratory disturbance index (r = 0.39, p < 0.01) and mean oxygen saturation (r = -0.36, p < 0.05). These variables, together with the time in slow-wave sleep, accounted for a statistically significant but modest percentage of the variance in urinary norepinephrine (R2 = 0.19, p < 0.05). However, the variables were so tightly intercorrelated that no single variable independently predicted norepinephrine levels in multiple regression analysis.

Adult↗

PubMed1997

Sleep problems in older adults: putting myths to bed.

Many people believe that older adults need less sleep. However, it is not the need for sleep but the ability to sleep that diminishes with age. Older adults are objectively sleepier in the day, indicating they are not getting enough sleep at night. Their sleep is disrupted by circadian rhythm changes, disorders such as sleep disordered breathing (apnea) and periodic limb movements in sleep (PLMS), medical illness, psychiatric illness, medication use, and poor sleep habits. The physician can address each of these causes, thereby improving the night-time sleep and daytime functioning of the older adult.

Aged↗

PubMed1997

Variations in circadian rhythms of activity, sleep, and light exposure related to dementia in nursing-home patients.

We measured 24-hour circadian-rhythm patterns of activity and sleep/wake activity in a group of nursing-home patients (58 women and 19 men with a mean age of 85.7 years). Severely demented patients were contrasted with a composite group of moderate y, mild, or not-demented patients. Sleep/wake activity and light exposure were recorded with the Actillume recorder. Cosinor analyses were computed to determine the mesor, amplitude, acrophase, and circadian quotient of the activity rhythms. The diagnosis of dementia was based on the Mini Mental Examination and on examination of medical records. Sleep was extremely fragmented in both groups of nursing-home patients. Severely demented patients slept more both at night and during the day, but there were no significant differences in the number of awakenings during the night or in the number of naps during the day when compared to the composite group of moderate, mild, or no-dementia patients. The severely demented group had lower activity mesor, more blunted amplitude, and were more phase delayed (i.e. had later acrophases) than the other group. In addition, the severely demented patients spent less time exposed to bright light. These results confirm that circadian rhythms in nursing-home patients are disturbed with more disturbance in the severely demented. Much of the disturbance may be related not just to age but to mental status.

Aged↗

PubMed1996

Sleep apnoea and sympathetic nervous system activity: a review.

A review was made of the literature relating sleep apnoea to sympathetic nervous system (SNS) activity, as inferred from catecholamine levels or muscle sympathetic nerve activity (MSNA). Twenty-four studies were located. Most studies reported an elevation of norepinephrine and MSNA, both during sleep and wakefulness among individuals with sleep apnoea. However, studies rarely controlled for known confounders of sympathetic activity, making the validity of the findings questionable.

Arousal↗

PubMed1996

Altered cardiac contractility in sleep apnea.

Adrenergic regulation in sleep apnea is a complex process because adrenergic physiology is difficult to summarize with one measure. Furthermore, the role of the adrenergic system in sleep apnea is often confounded with hypertension, making interpretation difficult in hypertensive apneics. Sixty-six people with and without apnea and/or hypertension (all were off antihypertensive medication) participated in this study. Cardiac beta-adrenergic drive, as assessed by systolic time intervals, was examined at rest and in response to a mild laboratory stressor. These measures of cardiac contractility included the pre-ejection period, electrical systole (QT) interval and the cardiac acceleration index. At rest, apneics showed elevated myocardial contractility on all measures (p = 0.001). In response to the laboratory stressor, non-apneics showed an increase in cardiac beta-adrenergic drive (p = 0.001), whereas the contractility in apneics did not change or decreased relative to baseline. These findings suggest disrupted cardiac adrenergic regulation in people with sleep apnea. Apnea appears to increase resting sympathetic activity and down regulate beta2-adrenergic receptors. The downregulation of cardiac beta-adrenergic receptor activity may explain the inability of people with sleep apnea to respond with appropriate cardiac contractility to a mild perturbation.

Adult↗

PubMed1996

Morbidity, mortality and sleep-disordered breathing in community dwelling elderly.

A population-based probability sample of elderly individuals (n = 426), who were originally studied between 1981 and 1986 (mean age at initial study was 72.5 years), were followed for mortality. Those with > or = 30 respiratory disturbances per hour of sleep had significantly shorter survival (p = 0.0034), but the respiratory disturbance index (RDI) was not an independent predictor of death. When Cox proportional hazards analysis was done, only age (the strongest predictor), cardiovascular disease and pulmonary disease were independent predictors of death. It may be that factors that are secondary to or associated with sleep-disordered breathing (SDB), such as cardiovascular or pulmonary disease, predispose these elderly to death.

Age Factors↗

PubMed1996

The role of sleep-disordered breathing in essential hypertension.

In recent years there have been numerous reports addressing the relationship between sleep-disordered breathing (SDB) and hypertension (HTN). This study investigated the relationship between SDB and BP after controlling for age, gross obesity, and notably, antihypertensive medications. Sixty-seven men and women between 30 and 60 years of age and between 0.90 to 1.5 times ideal body weight were studied. SDB was assessed over two nights of polysomnographic monitoring, and BP was measured over repeated visits to the hospital. The results indicate that respiratory disturbance index (RDI) independently predicts diastolic BP (DBP), accounting for 15% of the variance in DBP (p=0.02). In subjects with severe levels of SDB (RDI >30), RDI uniquely accounted for 36% of the variance in DBP (p=0.003). Interestingly, SDB was not independently related to systolic BP. The physiologic mechanisms responsible for these findings are currently being explored.

Adult↗

PubMed1995

Effect of bright light treatment on agitated behavior in institutionalized elderly subjects.

This study examined whether exposure to bright light treatment would reduce agitated behavior in institutionalized elderly subjects. Six demented elderly subjects (mean age = 89.2 years) living in a skilled nursing facility were studied. Light (2500 lx) was administered for 2 hours in the morning for two 10-day periods. The Bliwise Agitation Behavior Rating Scale was used to rate agitated behavior once every 15 min between 16:00 h and 20:00 h during 3 days of baseline, the light treatment periods, and 5 days of posttreatment follow-up evaluation. The entire protocol was then repeated in an ABABA design. A planned comparison revealed a significant difference between light treatment days and nontreatment days, with less agitation being observed on treatment days. The study suggests the efficacy of the clinical use of bright light treatment to reduce agitation.

Aged↗

PubMed1995

Beta 2-adrenergic receptor characteristics in sleep apnea patients.

This study examined the relationship between sleep apnea and beta 2-adrenergic receptor characteristics. Using standard polysomnography, individuals were classified as either apneic (n = 15) or mild to nonapneic (n = 15) according to their respiratory disturbance index (RDI). Subjects were similar in terms of sodium excretion and blood pressure. Apneic subjects showed a decrease in beta 2-adrenergic receptor sensitivity (p = 0.01) [as determined by isoproterenol-stimulated cyclic adenosine 5'-monophosphate (AMP) production in lymphocytes] and an increased binding affinity to the beta receptor antagonist [125I]iodopindolol (p < 0.001). beta receptor density was also diminished in apneics, but not significantly (p = 0.08). Forskolin-stimulated cyclic AMP was not significantly different between the groups, indicating a similarity in postreceptor Gs-adenylate cyclase activation. Across all subjects, RDI was negatively correlated with beta receptor sensitivity (r = -0.35, p = 0.05) and Kd (r = -0.54, p < 0.01) and positively correlated with systolic blood pressure (r = 0.37, p < 0.05). The findings indicate that sleep apnea is associated with a diminished beta 2-adrenergic receptor function but no change in postreceptor components and suggest a mechanism for the high comorbidity between sleep apnea and hypertension.

Adenosine Monophosphate↗

PubMed1995

Sleep-disordered breathing in African-American elderly.

Although sleep-disordered breathing (SDB) has been shown to be very prevalent in the elderly, little has been done to examine differences between the elderly of different racial groups. It has been well documented that SDB often results in hypertension and that hypertension is more common in African-Americans than in Caucasians. Therefore, one might suspect that SDB might be more common in African-Americans. Caucasians (n = 346) and African-Americans (n = 54) older than 65 yr of age were studied. African-Americans reported less satisfaction with sleep (p = 0.017), more difficulty falling asleep (p < 0.001), more daytime sleepiness (p = 0.0014), and more frequent morning headaches (p = 0.0043). African-Americans napped 0.8 times more frequently per evening (p = 0.05) and 11 min longer per nap (p = 0.019) than did Caucasians, and they showed a trend toward more total sleep time (428 versus 408 min). Of greater interest was the fact that more African-Americans had severe SDB with a relative risk twofold as great (relative risk = 2.13) as that for Caucasians, which was confirmed in a logistic regression analysis where race was associated with the presence of SDB (RDI > or = 30) independently of age, sex, and body mass index. The mean RDI for those African-Americans with severe SDB was significantly higher than that for Caucasians (72.1 versus 43.3; p = 0.014).

Black or African American↗

PubMed1995

The effect of sleep apnea on plasma and urinary catecholamines.

Numerous studies have suggested an alteration of sympathetic nervous system functioning in sleep apnea. However, most of these studies did not control for confounding factors such as diet, obesity, hypertension and anti-hypertensive medications. We examined plasma and urinary catecholamines in 43 patients, including hypertensive and normotensive individuals with and without sleep apnea. Hypertensive patients were studied at least 3 weeks following tapering of anti-hypertensive medication. All patients consumed similar diets and were of similar age and level of obesity. Twenty-four-hour urinary norepinephrine levels were significantly higher in apneics (58.2 ng vs. 40.2 ng in nonapneics, p < 0.002). Urinary norepinephrine in apneics was increased during both day and night. Plasma norepinephrine levels were not significantly elevated in apneic patients but were elevated in hypertensive patients both during sleep and in the morning (p < 0.05).

Adult↗

PubMed1995

The effect of hypoxia on baroreflexes and pressor sensitivity in sleep apnea and hypertension.

Many persons with sleep apnea are hypertensive. Forty-two subjects of similar age and weight were divided into four groups of hypertensives and normotensives with and without sleep apnea. All subjects had heart rate, blood pressure (BP), baroreflex sensitivity and pressor sensitivity to phenylephrine measured while breathing room air or 15% oxygen. Hypoxia raised heart rate and lowered BP in all groups (p < 0.001), with the greatest hypotensive effect among hypertensives. Hypertensives had blunted baroreflex sensitivity, and breathing a hypoxic mixture lowered baroreflex sensitivity of all four groups (p = 0.008). The apneic subjects tended to lower their baroreflex sensitivity more in response to hypoxia and also had an enhanced pressor response to phenylephrine, whether breathing room air or 15% oxygen. Episodes of sleep apnea lead to hypoxia, an initial period of hypotension and a subsequent increase in sympathetic nervous activity. Our studies suggest that apneics could have an exaggerated pressor sensitivity to norepinephrine. They might also have difficulty returning BP to normal levels, because hypoxia impaired baroreflexes.

Adult↗