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Showing papers in "Sleep in 1995"


Journal ArticleDOI
01 Jul 1995-Sleep
TL;DR: In multivariate analyses, sleep complaints were associated with an increasing number of respiratory symptoms, physical disabilities, nonprescription medications, depressive symptoms and poorer self-perceived health.
Abstract: The frequencies of five common sleep complaints--trouble falling asleep, waking up, awaking too early, needing to nap and not feeling rested--were assessed in over 9,000 participants aged 65 years and older in the National Institute on Aging's multicentered study entitled "Established Populations for Epidemiologic Studies of the Elderly" (EPESE). Less than 20% of the participants in each community rarely or never had any complaints, whereas over half reported at least one of these complaints as occurring most of the time. Between 23% and 34% had symptoms of insomnia, and between 7% and 15% percent rarely or never felt rested after waking up in the morning. In multivariate analyses, sleep complaints were associated with an increasing number of respiratory symptoms, physical disabilities, nonprescription medications, depressive symptoms and poorer self-perceived health. Sleep disturbances, particularly among older persons, oftentimes may be secondary to coexisting diseases. Determining the prevalence of specific sleep disorders, independent of health status, will require the development of more sophisticated and objective measures of sleep disturbances.

1,505 citations


Journal ArticleDOI
01 Jun 1995-Sleep
TL;DR: The data suggest that actigraphy, despite its limitations, may be a useful, cost-effective method for assessing specific sleep disorders, such as insomnia and schedule disorders, and for monitoring their treatment process.
Abstract: This paper, which has been reviewed and approved by the Board of Directors of the American Sleep Disorders Association, provides the background for the Standards of Practice Committee's parameters for the practice of sleep medicine in North America The growing use of activity-based monitoring (actigraphy) in sleep medicine and sleep research has enriched and challenged traditional sleep-monitoring techniques This review summarizes the empirical data on the validity of actigraphy in assessing sleep-wake patterns and assessing clinical and control groups ranging in age from infancy to elderly An overview of sleep-related actigraphic studies is also included Actigraphy provides useful measures of sleep-wake schedule and sleep quality The data also suggest that actigraphy, despite its limitations, may be a useful, cost-effective method for assessing specific sleep disorders, such as insomnia and schedule disorders, and for monitoring their treatment process Methodological issues such as the proper use of actigraphy and possible artifacts have not been systematically addressed in clinical research and practice

917 citations


Journal ArticleDOI
01 Aug 1995-Sleep
TL;DR: Comparison of the risk and benefit of oral appliance therapy with the other available treatments suggests that oral appliances present a useful alternative to continuous positive airway pressure (CPAP), especially for patients with simple snoring and patients with obstructive sleep apnea who cannot tolerate CPAP therapy.
Abstract: This paper, which has been reviewed and approved by the Board of Directors of the American Sleep Disorders Association, provides the background for the Standards of Practice Committee's parameters for the practice of sleep medicine in North America. The 21 publications selected for this review describe 320 patients treated with oral appliances for snoring and obstructive sleep apnea. The appliances modify the upper airway by changing the posture of the mandible and tongue. Despite considerable variation in the design of these appliances, the clinical effects are remarkably consistent. Snoring is improved and often eliminated in almost all patients who use oral appliances. Obstructive sleep apnea improves in the majority of patients; the mean apnea-hypopnea index (AHI) in this group of patients was reduced from 47 to 19. Approximately half of treated patients achieved an AHI of < 10; however, as many as 40% of those treated were left with significantly elevated AHIs. Improvement in sleep quality and sleepiness reflects the effect on breathing. Limited follow-up data indicate that oral discomfort is a common but tolerable side effect, that dental and mandibular complications appear to be uncommon and that long-term compliance varies from 50% to 100% of patients. Comparison of the risk and benefit of oral appliance therapy with the other available treatments suggests that oral appliances present a useful alternative to continuous positive airway pressure (CPAP), especially for patients with simple snoring and patients with obstructive sleep apnea who cannot tolerate CPAP therapy.

527 citations


Journal ArticleDOI
01 Sep 1995-Sleep
TL;DR: It was concluded that patients who report chronic insomnia may suffer from a more general disorder of hyperarousal that may be responsible for both the daytime symptoms and the nocturnal poor sleep.
Abstract: Groups of 10 objectively defined insomniacs and age-, sex- and weight-matched normal sleepers were evaluated on sleep, performance, mood, personality and metabolic measures over a 36-hour sleep laboratory stay. Insomniacs were defined to have increased wake time during the night but also had decreased stage 2 and rapid eye movement sleep. As expected insomniacs reported increased confusion, tension and depression and decreased vigor on the profile of mood states mood scale throughout the evaluation period as compared to the normals. Insomniacs also had decreased memory ability on the short-term memory test and the MAST. These performance and mood differences were not secondary to sleepiness because the insomniacs also had significantly increased multiple sleep latency test (MSLT) values throughout the evaluation period. In conjunction with the consistent mood, performance and MSLT differences during the day and the sleep differences at night, whole body VO2, measured at intervals across the day and throughout one night of sleep, was consistently elevated at all measurement points in the insomniacs as compared to the normals. The nocturnal increase in metabolic rate remained even after metabolic values from periods during the night containing wake time or arousals were eliminated from the data set. It was concluded that patients who report chronic insomnia may suffer from a more general disorder of hyperarousal (as measured here by a 24-hour increase in metabolic rate) that may be responsible for both the daytime symptoms and the nocturnal poor sleep. Future studies need to explore 24-hour insomnia treatment strategies that decrease hyperarousal.

513 citations


Journal ArticleDOI
01 Dec 1995-Sleep
TL;DR: Data show that significant sleep loss exists in one-third or more of normal adults, that the effects are large and replicable and that similar effects can be produced in just 1 night in the laboratory.
Abstract: Summary: Data from recent laboratory studies indicate that nocturnal sleep periods reduced by as little as 1.3 to 1.5 hours for 1 night result in reduction of daytime alertness by as much as 32% as measured by the Multiple Sleep Latency Test (MSLT). Other data document that 1) 170/0--57% of normal young adults have MSLT latencies of ::;5.5 minutes, whereas ::;50% have MSLT values of ~ 10 minutes and 2) 28°/0--29% of young adults reported normally sleeping ::;6.5 hours on each weeknight. More extensive reduction of daily sleep amount is seen in night­ shift workers. A minimum of 2%-4% of middle-aged adults have hypersomnolence associated with sleep apnea. Together, these data show that significant sleep loss exists in one-third or more of normal adults, that the effects are large and replicable and that similar effects can be produced in just I night in the laboratory. In light of the magnitude of this sleep debt, it is not surprising that fatigue is a factor in 57% of accidents leading to the death of a truck driver and in 10% of fatal car accidents and results in costs of up to 56 billion dollars per year. A recent sleep extension study suggests that the average underlying sleep tendency in young adults is about 8.5 hours per night. By comparison, the average reported sleep length of 7.2-7.4 hours is deficient, and common sleep lengths of ::;6.5 hours can be disastrous. We must recognize the alertness function of sleep and the increasing consequences of sleepiness with the same vigor that we have come to recognize the societal impact of alcohol. Key Words: Sleep deprivation-Sleepiness-Sleep disorders- Work schedule tolerance. Weare in the midst of a golden age of discovery of the intricate interrelationship between our nocturnal sleep process and our level of daytime function. Fueled by the discovery of the tremendous incidence of sleep apnea and periodic leg movements in the population, the relationship between fragmented sleep and residual sleepiness, as well as the increased ability to measure the level of objective sleepiness with an objective test [the Multiple Sleep Latency Test (MSLT)] and in am­ bulatory environments, the pervasive role of excessive sleepiness in our society is becoming apparent. Much literature documents the negative effects of sleep deprivation on a wide range of psychomotor per­ formance tasks and mood variables. For the sake of simplicity, the primary outcome measure reported in this paper will be MSL T. However, the MSL T findings reported are consistent with similar changes in a broad range of abilities, including reaction time, short-term memory, vigilance and mood (1). Many empirical and applied studies have provided evidence for our national sleep debt. The degree of our

483 citations


Journal ArticleDOI
01 Apr 1995-Sleep
TL;DR: Questionnaire data from patients presenting at three sleep disorders centers were used to develop and assess a screening tool for sleep apnea based on the reporting of the frequency of various symptoms ofsleep apnea and other sleep disorders plus age, body mass index (BMI) and gender.
Abstract: Questionnaire data from patients presenting at three sleep disorders centers were used to develop and assess a screening tool for sleep apnea based on the reporting of the frequency of various symptoms of sleep apnea and other sleep disorders plus age, body mass index (BMI) and gender. Patients were not specifically referred for suspicion of sleep apnea. Separate factor analyses of survey responses from 658, 193 and 77 respondents from the first, second and third sites, respectively, each yielded four orthogonal factors, one of which accounted for all the questions concerned with the frequency of disordered breathing during sleep. The survey was shown to be reliable in a subset of patients from one of the sites (test-retest correlation = 0.92). Survey data were then compared to a clinical measure of sleep apnea (respiratory disturbance index) obtained from polysomnography. A multivariable apnea risk index including survey responses, age, gender and BMI was estimated using multiple logistic regression in a total sample of 427 respondents from two of the sites. Predictive ability was assessed using receiver operating characteristic (ROC) curves. The area under the ROC curve was 0.79 (p < 0.0001). For BMI alone, it was 0.73, and for an index measuring the self-report of the frequency of apnea symptoms, it was 0.70. The multivariable apnea risk index has potential utility in clinical settings.

464 citations


Journal ArticleDOI
01 Apr 1995-Sleep
TL;DR: It is interpreted to suggest that SAS affects death indirectly, most probably by being a risk factor for hypertension.
Abstract: During 1976-1988 we diagnosed sleep apnea syndrome (SAS) in 1,620 adult men and women monitored in the Technion sleep laboratories. Their age at the time of diagnosis ranged between 21 and 79 years. Fifty-seven patients (53 men and 4 women) had died by 1990, 53% due to respiratory-cardiovascular causes. The observed/expected (O/E) mortality rates, calculated for men only, revealed excess mortality of patients under 70 years old. Excess mortality was significant in the fourth and fifth decades (3.33, p < 0.002; 3.23, p < 0.0002, respectively). In patients older than 70 O/E was 0.33 (p < 0.0007). Hierarchical multivariate analysis with four fixed variables [age, body mass index (BMI), hypertension and apnea index] and four additional variables added manually one at a time (heart disease, lung disease, diabetes, apnea duration) was used to determine the predictors of death from all causes, cardiopulmonary causes and from myocardial infarction (MI). All four major variables were found to be significant predictors of mortality from all causes, in addition to lung disease and heart disease. Only age and BMI were significant predictors of cardiopulmonary deaths in addition to lung disease. Age, BMI and hypertension predicted MI deaths in addition to lung disease. These results were interpreted to suggest that SAS affects death indirectly, most probably by being a risk factor for hypertension.

391 citations


Journal ArticleDOI
01 Jan 1995-Sleep
TL;DR: Patients with sleep apnea syndrome were found to have a significantly decreased ability to initiate new mental processes and to inhibit automatic ones, in conjunction with a tendency for preservative errors, and had reduced memory spans.
Abstract: Impairment of cognitive executive functions previously has been suspected to occur in association with sleep apnea syndrome (SAS), as suggested by some neuropsychological studies. However, such functions have not been assessed directly. In the present study, 17 patients with SAS were evaluated with various focused frontal lobe-related tests in comparison with 17 normal controls. Such tasks explored attention, short-term memory spans, learning abilities, planning and programming capacities, categorizing activities and verbal fluency. Patients were found to have a significantly decreased ability to initiate new mental processes and to inhibit automatic ones, in conjunction with a tendency for preservative errors. They were also affected with deficits of verbal and visual learning abilities and had reduced memory spans. Such defects were further evaluated via logistic regression against two criteria of the severity of the disease: the number of apneas and hypopneas per hour of sleep and the level of nocturnal hypoxemia. Memory deficits were rather related to the former, whereas typical frontal lobe-related abnormalities seemed rather consistent with the latter. These findings are discussed in light of data from the literature concerning cognitive impairments described for patients with isolated daytime sleepiness versus hypoxemia, as illustrated in other pathological or physiological circumstances.

376 citations


Journal ArticleDOI
01 Sep 1995-Sleep
TL;DR: It is suggested that for melatonin-deficient elderly insomniacs, melatonin replacement therapy may be beneficial in the initiation and maintenance of sleep.
Abstract: Changes in sleep-wake patterns are among the hallmarks of biological aging. Previously, we reported that impaired melatonin secretion is associated with sleep disorders in old age. In this study we investigated the effects of melatonin replacement therapy on melatonin-deficient elderly insomniacs. The study comprised a running-in, no-treatment period and four experimental periods. During the second, third and fourth periods, subjects were administered tablets for 7 consecutive days, 2 hours before desired bedtime. The tablets were either 2 mg melatonin administered as sustained-release or fast-release formulations, or an identical-looking placebo. The fifth period, which concluded the study, was a 2-month period of daily administration of 1 mg sustained-release melatonin 2 hours before desired bedtime. During each of these five experimental periods, sleep-wake patterns were monitored by wrist-worn actigraphs. Analysis of the first three 1-week periods revealed that a 1-week treatment with 2 mg sustained-release melatonin was effective for sleep maintenance (i.e. sleep efficiency and activity level) of elderly insomniacs, while sleep initiation was improved by the fast-release melatonin treatment. Sleep maintenance and initiation were further improved following the 2-month 1-mg sustained-release melatonin treatment, indicating that tolerance had not developed. After cessation of treatment, sleep quality deteriorated. Our findings suggest that for melatonin-deficient elderly insomniacs, melatonin replacement therapy may be beneficial in the initiation and maintenance of sleep.

341 citations


Journal ArticleDOI
01 Dec 1995-Sleep
TL;DR: Fatigue ratings and the theta/ alpha power density of the waking EEG recorded at the same four time points during the constant routine protocol correlated significantly, demonstrating the presence of a homeostatic component in the control of EEG power density in the 6.25- to 9.0-Hz range.
Abstract: Electroencephalogram (EEG) power density and self-rated fatigue were assessed in nine healthy women during a 40-hour period of sustained wakefulness under constant behavioral and environmental conditions (constant routine protocol). Waking EEG recordings were performed for 4 minutes after 3, 10, 27 and 34 hours of prior wakefulness. EEG power density in the 6.25- to 9.0-Hz frequency range progressively increased across the four recordings, suggesting an endogenous homeostatic component in the regulation of the theta/alpha frequencies under constant conditions. Subjective fatigue also exhibited an increasing component in the course of the constant routine protocol, with a clear circadian modulation. Fatigue ratings and the theta/ alpha power density of the waking EEG recorded at the same four time points during the constant routine protocol correlated significantly. Our data demonstrate the presence of a homeostatic component in the control of EEG power density in the 6.25- to 9.0-Hz range.

336 citations


Journal ArticleDOI
01 Jan 1995-Sleep
TL;DR: These clinical guidelines, which have been reviewed and approved by the Board of Directors of the American Sleep Disorders Association (ASDA), provide recommendations for the practice of sleep medicine in North American with regards to the use of oral appliances for the treatment of snoring and obstructive sleep apnea.
Abstract: These clinical guidelines, which have been reviewed and approved by the Board of Directors of the American Sleep Disorders Association (ASDA), provide recommendations for the practice of sleep medicine in North American with regards to the use of oral appliances for the treatment of snoring and obstructive sleep apnea. Oral appliances have been developed for the treatment of snoring and have been applied to the treatment of obstructive sleep apnea, a syndrome associated with morbidity. Based on a review of the relevant scientific literature, the Standards of Practice Committee of the ASDA has developed guidelines describing the use of oral appliances for the treatment of snoring and obstructive sleep apnea in adults.

Journal ArticleDOI
01 Aug 1995-Sleep
TL;DR: Evidence suggests that, within the waking state, the BF cholinergic system modulates processing of sensory information in the neocortex and is involved in cognitive processes, and a critical role for GABAergic-cholinergic interactions, both within the magnocellular BF and at cortical and diencephalic sites, in the regulation of behavioral state is supported.
Abstract: Magnocellular regions of the basal forebrain (BF) are recognized as important sites of sleep-wake regulation. Evidence is reviewed for the coexistence within the BF of mechanisms that regulate neocortical and limbic system arousal along with mechanisms that promote sleep. Arousal-related functions are mediated by a system of magnocellular cholinergic neurons. BF cholinergic neurons project monosynaptically to the entire neocortex and limbic telencephalon, exert excitatory effects on target cells and participate in the regulation of activated EEG patterns characteristic of waking and REM sleep. Evidence suggests that, within the waking state, the BF cholinergic system modulates processing of sensory information in the neocortex and is involved in cognitive processes. One or more noncholinergic cell types are responsible for the sleep-promoting functions of the BF. Neurons that display elevated discharge rates during transitions from waking to sleep and during nonREM sleep have been recorded in BF sites where electrical stimulation evokes sleep and experimental lesions cause insomnia. BF neurons function to promote sleep, in part, via descending inhibition of caudal hypothalamic and brainstem activating systems. GABAergic neurons located within magnocellular regions of the BF are hypothesized to mediate sleep-promoting actions. Afferents to the BF from hypothalamic and brainstem regions are functionally important for sleep-wake regulation. Thermosensitive inputs from the anterior hypothalamus modulate the activity of BF sleep- and arousal-related cell types. Excitatory effects of brainstem inputs to BF arousal-related cells have been documented. Additional evidence supports a critical role for GABAergic-cholinergic interactions, both within the magnocellular BF and at cortical and diencephalic sites, in the regulation of behavioral state.

Journal ArticleDOI
01 Mar 1995-Sleep
TL;DR: Women reported more awakenings, more total time spent awake during the night and poorer sleep quality; all these findings were most evident in the older women, who also took longer to fall asleep than any other group.
Abstract: Home-based sleep was monitored by morning logs and wrist actimetry for 15 nights in a sample of 400 adults (20-70 years old; 211 female, 189 male; one per household). Subjects on sleep-enhancing medications and/or whose sleep was severely disturbed by illness were excluded. Subjects were grouped into age bands: ("young" = 20-34 years, "mid-aged" = 35-49 years and "older" = 50-70 years). Women retired to bed and fell asleep earlier than men. Men and women woke up earlier with increasing age. Sleep period time was markedly longer for women. Most reported awakenings were < 5 minutes. Women reported more awakenings, more total time spent awake during the night and poorer sleep quality; all these findings were most evident in the older women, who also took longer to fall asleep than any other group. Although these age effects are consistent with those reported elsewhere, the gender effects, some of which are much stronger than the age effects, have not been so evident before.

Journal ArticleDOI
01 Oct 1995-Sleep
TL;DR: It is concluded that L-dopa 100-200 mg proved to be effective in idiopathic RLS and for the first time under controlled conditions in uremic R LS without any severe side effects.
Abstract: We report the effects of a single bedtime dose of L-dopa 100-200 mg on sleep quality, frequency of periodic leg movements (PLM) and daily living in patients with idiopathic and uremic restless legs syndrome (RLS) Seventeen patients with idiopathic and 11 with uremic (on continuous hemodialysis) RLS were evaluated comparatively by polysomnography, actigraphy and subjective ratings in a randomized, controlled and double-blind crossover trial with L-dopa and placebo for 4 weeks each Neurophysiologic assessments showed significant reduction of the number of periodic leg movements (p = 0003) and the PLM-index (p = 0005) most pronounced during the first 4 hours of bedtime after L-dopa (p = 0001) Subjective evaluation confirmed improvement of sleep quality (p = 0002) and showed significantly higher quality of life during daytime (p = 0030) while the patients received L-dopa therapy We conclude that L-dopa 100-200 mg proved to be effective in idiopathic RLS and for the first time under controlled conditions in uremic RLS without any severe side effects

Journal ArticleDOI
01 Jun 1995-Sleep
TL;DR: Results showed that subgroups, formed on the basis of presenting complaints and diagnostic criteria, differed in regard to the magnitude and direction of their sleep distortions, which appeared consistent with the types of objective sleep disturbances these subgroups commonly experience.
Abstract: It is well recognized that sleep time misperceptions are common among insomniacs, but little is known about the distribution and clinical significance of these subjective distortions. The current investigation was conducted to examine the distribution of sleep time misperceptions among a large (n = 173), diverse group of insomniacs and to determine if such misperceptions might relate to the patients' clinical characteristics. Consistent with previous studies, our subjects, as a group, produced sleep estimates that were significantly (p < 0.0001) lower than polysomnographically determined sleep times. However, patients' sleep time perceptions were widely distributed across a broad continuum, which ranged between gross underestimates and remarkable overestimates of actual sleep times. Results also showed that subgroups, formed on the basis of presenting complaints and diagnostic criteria (i.e. International Classification of Sleep Disorders nosology), differed in regard to the magnitude and direction of their sleep distortions. Moreover, these differences appeared consistent with the types of objective sleep disturbances these subgroups commonly experience. Hence, the tendency to underestimate actual sleep time is not a generic attribute of all insomniacs. Furthermore, it appears that the accuracy and nature of sleep time perceptions may relate to the type of sleep pathology underlying insomniacs' presenting complaints.

Journal ArticleDOI
01 Sep 1995-Sleep
TL;DR: The prevalence of DIS was fairly similar at these four European centers but that there was a variation in the prevalence of nightmares and nocturnal awakenings.
Abstract: The aim of this investigation was to study the geographic variation in sleep complaints and to identify risk factors for sleep disturbances in three European countries: Iceland (Reykjavik), Sweden (Uppsala and Goteborg) and Belgium (Antwerp). The study involved a random population of 2,202 subjects (age 20-45 years) who participated in the European Community Respiratory Health Survey. The subjects answered a questionnaire on sleep disturbances. Participants in Iceland and Sweden also estimated their sleep habits and sleep times during a period of 1 week in a sleep diary. Habitual (> or = 3/week) difficulties inducing sleep (DIS) were reported by 6-9% and early morning awakenings by 5-6% of the subjects. The estimated number of awakenings and the prevalence of nightmares was significantly lower in Reykjavik. Participants in Reykjavik went to bed at night and woke in the morning approximately 1 hour later than participants at the Swedish centers (p < 0.001). Symptoms of gastroesophageal reflux (GER) were associated with DIS (odds ratio [OR] = 2.7), nightmares (OR = 4.4), longer sleep latency and frequent nocturnal awakenings. Smoking correlated positively to DIS (OR = 1.8) and estimated sleep latency. We conclude that the prevalence of DIS was fairly similar at these four European centers but that there was a variation in the prevalence of nightmares and nocturnal awakenings. The significant correlation between reported GER and subjective quality of sleep should be followed up in studies using objective measurements.

Journal ArticleDOI
01 Jun 1995-Sleep
TL;DR: It is important that those scoring arousals on routine polysomnography recognize that high arousal frequencies occur in the normal population on 1-night polysOMnography, as well as those scoring brief arousals according to three different criteria, including the ASDA definition.
Abstract: Brief arousals are clinically important and increasingly scored during polysomnography. However, the frequency of arousals during routine polysomnography in the normal population is unknown. We performed overnight polysomnography in the 55 of 59 control subjects from a family practice list who were approached and agreed to undergo polysomnography. Awakenings were scored according to the criteria of Rechtschaffen and Kales and briefer arousals according to three different criteria, including the American Sleep Disorders Association (ASDA) definition. There was a mean of 4 [95% confidence interval (CI), 1-15) Rechtschaffen and Kales awakenings per hour, whereas the ASDA definition gave 21 (95% CI, 7-56) per hour slept. Arousal frequencies increased significantly (p < 0.001) with age in our subjects, who ranged from the late teens to early 70s. The high upper limit of the frequency of brief arousals was not altered by exclusion of patients who snored or had witnessed apneas or daytime sleepiness. It is important that those scoring arousals on routine polysomnography recognize that high arousal frequencies occur in the normal population on 1-night polysomnography.

Journal ArticleDOI
01 Jan 1995-Sleep
TL;DR: The homeostatic and circadian component of a quantitative (computerized) three-process model for predicting alertness/sleepiness in daily living is validated and it is suggested that the studied components of the model may serve as tools for evaluating work/rest schedules in terms of sleep-related safety risks.
Abstract: This paper summarizes work to validate and develop further the homeostatic and circadian component of a quantitative (computerized) three-process model for predicting alertness/sleepiness in daily living. The model uses sleep data as input and contains circadian and homeostatic components (amount of prior wake and amount of prior sleep), which are summed to yield predicted alertness on a scale between 1 and 16. The present validation was carried out using regression analysis, with sleepiness-related electroencephalographic parameters (alpha power density) from field and laboratory studies as criteria. The results showed that variations in alpha-power density in truck drivers, train drivers and laboratory subjects could be predicted with considerable accuracy (r2 > 0.70) from the model, as could subjective alertness. Levels < or = 7 on the 16-point scale were defined as critically low alertness. The paper also describes a simplified, graphic, paper version of the computation model, visualized as a two-dimensional "alertness nomogram". It is suggested that the studied components of the model may serve as tools for evaluating work/rest schedules in terms of sleep-related safety risks.

Journal ArticleDOI
01 Jun 1995-Sleep
TL;DR: In this paper, the authors examined plasma and urinary catecholamines in 43 patients, including hypertensive and normotensive individuals with and without sleep apnea, at least 3 weeks following tapering of anti-hypertensive medication.
Abstract: 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 (582 ng vs 402 ng in nonapneics, p < 0002) 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 < 005)

Journal ArticleDOI
01 Aug 1995-Sleep
TL;DR: The results showed clearly that there was a first-night effect in normal subjects, similar to that reported in previously published data, characterized by a longer rapid eye movement (REM) sleep latency (p < 0.05), increased wakefulness, and total sleep time and a decreased sleep efficiency.
Abstract: The goal of the present study was to evaluate the first-night effect in psychiatric inpatients using large subject samples (n > 30) in order to obtain a good statistical evaluation. Thirty-two normal subjects and 94 psychiatric inpatients (38 depressives and 56 insomniacs) were studied for three consecutive nights in the hospital sleep laboratory. Our results showed clearly that there was a first-night effect in normal subjects, similar to that reported in previously published data, characterized by a longer rapid eye movement (REM) sleep latency (p < 0.05), increased wakefulness (p < 0.01) and total sleep time (p < 0.02) and a decreased sleep efficiency (p < 0.01). REM sleep latency and stage REM in the first third of the night were still altered in the second night. Both clinical groups had a less marked first-night effect than normal subjects, showing alterations only observed in REM sleep (p < 0.01) (decreased REM sleep, longer REM sleep latency, increased REM sleep gravity center). However, the first-night effect was more pronounced in insomniacs than in depressed patients. No statistical differences between the second and third nights' recordings were found in sleep parameters. It is suggested that first-night data should not be simply discarded but could be used in subsequent analyses.

Journal ArticleDOI
01 Oct 1995-Sleep
TL;DR: The self-reported daily sleep time of students declined, and daytime sleepiness and moodiness increased in the higher grades, and the girls slept fewer hours than the boys and did not show an increase in daytimeSleepiness.
Abstract: The objective of this work was to study the relationship between daily sleep time and characteristics of students, e.g. grade level, gender, and academic program. A sleep habit questionnaire was designed to survey students at two junior high schools, one from northern Taipei and the other from southern Taipei. The impact of shortened duration of sleep on daily function was also evaluated. A total of 965 students and their parents were selected randomly in December 1993 for the questionnaire study. The response rate was 96.4% (930) for students and 88.6% (855) for parents. The self-reported daily sleep time of students declined, and daytime sleepiness and moodiness increased in the higher grades. The girls slept fewer hours than the boys and did not show an increase in daytime sleepiness. Those students not taking the senior high school joint entrance examination slept more hours at night and maintained more alertness in the daytime than those who were taking the examination. The more academic pressures that adolescents faced, the fewer hours they slept. Students not participating in the joint entrance examination seemed to show a healthier sleep pattern. Little sleep at night made the students feel sleepy in the daytime and tired, drowsy, moody and difficult at arising in the morning. The reason why girls slept less than boys needs further investigation.


Journal ArticleDOI
01 Apr 1995-Sleep
TL;DR: It is concluded that patients with OSA may exhibit decreased fibrinolytic activity, which may represent a confounding pathophysiological mechanism behind the high incidence of myocardial infarction and stroke in patientsWith OSA.
Abstract: Platelet function and fibrinolytic activity was studied during rest and after ergometric exercise in 13 hypertensive or normotensive patients with obstructive sleep apnea (OSA) and in 10 sex- and weight-matched controls. All patients had undergone a complete polysomnography for the diagnosis of OSA. The controls did not undergo any sleep investigation but had no history of snoring or witnessed apneas during sleep. On antihypertensive drug wash-out, two of the patients were normotensive, whereas 11 had mild to moderate hypertension. Platelet aggregation measured by adenosine 5'-diphosphate- or adrenaline-induced aggregation, platelet factor-4 or beta-thromboglobulin did not differ between patients and controls. During exercise beta-thromboglobulin decreased significantly in both OSA patients and controls. Plasma tissue plasminogen activator activity was similar in OSA patients and controls and increased significantly in both groups after exercise. Plasminogen activator inhibitor type 1 (PAI-1) was 18.4 +/- 3.6 IU/ml in OSA patients compared with 8.2 +/- 1.7 IU/ml in controls (p < 0.029) during rest, indicating decreased fibrinolytic activity. The difference between groups remained after exercise (p < 0.017). Blood pressure elevation was more common and body mass index (BMI) was higher in patients with OSA, but there was no direct relation between blood pressure level or BMI and PAI-1. Nevertheless, differences between groups were smaller when blood pressure and obesity were accounted for. It is concluded that patients with OSA may exhibit decreased fibrinolytic activity. Low fibrinolytic activity may represent a confounding pathophysiological mechanism behind the high incidence of myocardial infarction and stroke in patients with OSA.

Journal ArticleDOI
01 Jan 1995-Sleep
TL;DR: Bright light is clearly superior in its ability to phase shift the circadian system and thereby improve sleep and performance and melatonin may permit shift workers to override the circadianSystem for short periods and avoid the potential toxicity due to overzealous manipulations of the circadian pacemaker.
Abstract: Chronic circadian disturbance is thought to cause many of the health and social problems reported by shift workers. In recent years, appropriately timed exposure to bright light and exogenous melatonin have been used to accelerate adaptation to phase shifts of the circadian system. In this study we compared adaptation to night shift in three groups of subjects. The first treatment group received timed exposure to bright light (4-7,000 lux between 2400 and 0400 hours on each of three night shifts). The second treatment group received exogenous melatonin by capsule (2 mg at 0800 hours then 1 mg at 1100 and 1400 hours). The placebo control groups received either dim red light at less than 50 lux or placebo (sucrose) in identical capsules at the same time. Results indicated that all groups shifted significantly from baseline. Using the dim-light melatonin onset as a circadian marker, the bright-light group shifted the furthest, whereas there was no significant difference between the melatonin and placebo groups. Sleep quality as determined by wrist actigraphy was most improved in the light-treatment group, although the melatonin group also showed significant improvements. Cognitive psychomotor performance was most improved in the light-treatment group and the melatonin group again showed little difference from the control group. Although melatonin was unable to increase the amount of the phase shift following transition to night shift, it is likely that the intermediate levels of improvement in sleep reflect the hypothermic effects of melatonin. By lowering core temperature across the sleep period, sleep may be enhanced. This improvement in sleep quality did not produce concomitant improvements in shift performance for the melatonin group. This suggests that the enhanced performance in the light-treatment group may reflect more direct "energizing" effects. On the basis of these results, bright light is clearly superior in its ability ot phase shift the circadian system and thereby improve sleep and performance. However, melatonin may permit shift workers to override the circadian system for short periods and avoid the potential toxicity due to overzealous manipulations of the circadian pacemaker. In rapidly rotating shift schedules, melatonin may be preferable because it would not require workers to reverse the large phase shift induced by light.

Journal ArticleDOI
01 Apr 1995-Sleep
TL;DR: The results suggest that suppression of secretion of growth hormone in untreated OSA results in impaired lipolysis, which is rapidly reversed by nasal CPAP.
Abstract: Nocturnal secretion of growth hormone is impaired in patients with obstructive sleep apnea (OSA), but the metabolic consequences have not been reported. We measured blood levels of the hormones insulin, C-peptide, growth hormone, cortisol and glucagon together with the intermediary metabolites of carbohydrate (glucose, pyruvate, lactate, alanine) and lipid metabolism [glycerol, nonesterified fatty acids (NEFA), 3-hydroxybutyrate] in six obese nondiabetic men with OSA on two nights. In the first study, the untreated subjects showed frequent apneas and consequent hypoxemia. The hormone and metabolite concentrations were compared with those obtained on the following night when the subjects were treated effectively with nasal continuous positive airway pressure (CPAP). There were no significant differences in the concentrations of insulin, C-peptide, cortisol or glucagon. We confirmed a marked reduction in growth hormone concentrations in OSA, with a significant increase on the CPAP night. The nocturnal profiles of glucose, pyruvate, lactate, alanine and glycerol showed no differences between the two nights, but concentrations of NEFA and 3-hydroxybutyrate, both products of lipolysis, were significantly greater on the treatment night. Because growth hormone has a lipolytic action, the results suggest that suppression of secretion of growth hormone in untreated OSA results in impaired lipolysis, which is rapidly reversed by nasal CPAP.

Journal ArticleDOI
01 Jun 1995-Sleep
TL;DR: The present findings show a linear increase in EEG power and RT with TSD, and a diurnal oscillation of EEG power, which is independent of TSD.
Abstract: Nine paid volunteers were sleep deprived over a period of 40 hours. Every 2 hours during total sleep deprivation (TSD) and after recovery sleep, oral temperature (OT), reaction time (RT) in a vigilance task and electroencephalogram (EEG) with eyes open and closed (C3, C4, T3 and T4) were recorded. Ten artifact-free samples from each condition were Fourier transformed. Absolute power was calculated for six bands. Analyses of variance with deprivation and time of day as factors showed the following significant results : 1) TSD induced an increase in RT, of theta power in all derivations, of beta power in both centrals and a decrease of alpha power with eyes closed ; OT was not affected. 2) All bands showed a peak of power at 1800 hours, 2 hours in advance of the OT acrophase at 2000 hours. All variables recovered baseline values after 1 night of sleep. Significant linear correlations of hours of wakefulness with EEG and RT, and of EEG power with OT and RT, were observed. The present findings show a linear increase in EEG power and RT with TSD, and a diurnal oscillation of EEG power, which is independent of TSD.

Journal ArticleDOI
01 Mar 1995-Sleep
TL;DR: Results showed that there were no differences in nap patterns based on gender, ordinal position, whether naps spontaneously disappeared or were stopped by the parents, and the number of naps at 6 months of age.
Abstract: A cohort of 172 children was followed from 6 months to 7 years of age to determine how nap patterns change with age and whether there was individual stability of nap patterns. Results showed that there were no differences in nap patterns based on gender, ordinal position, whether naps spontaneously disappeared or were stopped by the parents, and the number of naps at 6 months of age. Total daytime sleep remained a stable individual characteristic between 6 and 18 months of age. Age was associated with hours napping (r = -0.73, p < 0.001) and number of naps (r = -0.52, p < 0.001). A pattern of two naps per day was well established by 9-12 months of age and one afternoon nap by 15-24 months. The modal duration of naps from 2 to 6 years was 2 hours. During the 3rd and 4th year, napping occurred in the majority of children, but at decreasing rates. A minority of children were napping at 5 and 6 years and naps usually disappeared by age 7.


Journal ArticleDOI
01 Sep 1995-Sleep
TL;DR: The notion that gender-related anatomical differences have a general effect on EEG amplitude, including during slow-wave sleep, supports the notion that aging affects the neurophysiologicalSlow-wave-generating mechanism.
Abstract: Low-frequency EEG was analyzed quantitatively during 2 nights in 40 females and 34 males aged 26 to 101 years. Analyses were based on Rechtschaffen and Kales NREM sleep stages, on absolute low-frequency amplitude (i.e. power in the range of 0.2-2.0 Hz) and on low-frequency continuity. The latter parameter describes how much (0-100%) of the current slow-wave activity is continued in the near-future EEG. Such continuation can occur through closed loops in the underlying neuronal network and cells. These loops are slow, thus corresponding to slow-wave frequencies, and can consist of electrophysiological, chemical and/or other pathways. The continuity percentage then monitors the relative activity of these loops. It does not depend directly on absolute EEG amplitudes. All analyzed parameters, including amplitude-independent continuity, decreased substantially and significantly with increasing age. The amplitudes of low-frequency EEG in females were significantly and substantially (40%) larger than those in males. However, the amplitude-independent continuity percentage did not differ between the genders. These findings support the notion that gender-related anatomical differences have a general effect on EEG amplitude, including during slow-wave sleep. Aging, however, specifically affects the neurophysiological slow-wave-generating mechanism.

Journal ArticleDOI
01 Mar 1995-Sleep
TL;DR: The present study compared the effects of repeated versus single-dose administration of caffeine and varying amounts of sleep taken prior to sleep loss on performance, mood and physiological measures during 2 nights and days of sleep loss.
Abstract: Previous studies have shown that performance during sleep loss is improved by prophylactic naps as a function of varying nap length. Based on single-dose caffeine studies, a similar dose-response effect has been hypothesized on performance, alertness and mood during sleep loss. The present study compared the effects of repeated versus single-dose administration of caffeine and varying amounts of sleep taken prior to sleep loss on performance, mood and physiological measures during 2 nights and days of sleep loss. A total of 140 normal, young adult males participated at one of two study sites. Ninety-eight subjects at one site were randomly assigned to one of four nap conditions (0, 2, 4 or 8 hours) and 42 subjects at the second site were assigned to one of four caffeine conditions. After a normal baseline night of sleep and morning baseline tests of performance, mood and nap latency, subjects in the nap groups returned to bed at noon, 1600 hours, 1800 hours or not at all. Bedtimes were varied so that all naps ended at 2000 hours. Subjects in the caffeine groups received either a single 400-mg dose of caffeine at 0130 hours each night or repeated doses of 150 or 300 mg every 6 hours starting at 0130 hours on the 1st night of sleep loss. A placebo control group (no nap and placebo administered every 6 hours on the repeated caffeine schedule) was run at both sites.(ABSTRACT TRUNCATED AT 250 WORDS)