SLEEP

Post, Elizabeth, J.;Wood, Andrew, K.;Page,, Megan;Jeffery, Heather, E.

doi: 10.1093/sleep/18.5.309pmid: N/A

Summary: A healthy neonatal piglet model was developed to investigate the effects of simulated gastro-esophageal reflux (GER) on airway protective mechanisms in different sleep states. Piglets were chosen for the model because there are similarities in esophageal morphology, development of the cardiorespiratory system and sleep-wakefulness cycle between the piglet and the human infant. Unanesthetized piglets were instrumented and trained to sleep in a radiolucent, temperature-controlled box. Physiologic recordings of sleep (electroencephalogram, ‘ear-o-gram’, behavioral observations), cardiorespiratory function (end-tidal CO2, O2 saturation, heart rate, respiratory movements), swallowing (pharyngeal or esophageal pressures) and GER (signaled by a fall in esophageal pH) were displayed and stored on a computer. An image intensifier was used for radiographic observations. The outputs from the computer and image intensifier were synchronized and recorded on videotape. The method enabled simultaneous physiologic and radiographic observations to be made during the simulation of GER by the injection of normal NaCl, distilled water or HCl (pH 2 and 3) into either the pharynx or different sites in the esophagus. The piglet model appears to accurately reflect the normal physiologic responses of the healthy sleeping neonate. Piglet model, Airways protective reflexes, Gastro-esophageal reflux, Pharynx, Esophagus, Sudden infant death This content is only available as a PDF.

Bergmann, Bernard, M.;Gilliland, Marcia, A.;Balzano,, Stefano;Refetoff,, Samuel;Rechtschaffen,, Allan

doi: 10.1093/sleep/18.5.317pmid: 7676163

Summary: Chronic total sleep deprivation (TSD) in the rat produces an initial elevation and then declining body temperatures, increasing metabolic rate and eventual death. Because TSD rats will engage in warming behavior, one hypothesis is that the metabolic increase is an unsuccessful attempt at warming to combat a lethal hypothermia. However, TSD rats also undergo weight loss and progressive deterioration of skin and fur, suggesting TSD-induced pathological catabolic activity, possibly secondary to increased metabolic rate, that could be lethal. To evaluate these alternatives, the metabolic rate of rats was increased by thyroxine (T4) treatment while subjecting them to TSD. Compared to TSD rats not given T4, they had higher metabolic rates, higher body temperatures and reduced warming behavior, but their survival period was 37% shorter. Thus, it is unlikely that hypothermia is the cause of death in TSD rats. Weight and appearance declined more rapidly in T4-treated rats, but at the same proportions of survival time, skin pathology and decline in appearance were less evident in T4-treated rats than in TSD rats not given T4. Thus, there is some doubt whether a general pathological catabolic process is the cause of death. It is also possible that a specific morbid process normally reversed by sleep was accelerated by T4 administration. Body temperature, Metabolic rate, Sleep, Sleep deprivation, Thyroxine. This content is only available as a PDF. Author notes ‡ Deceased. © 1995 American Sleep Disorders Association and Sleep Research Society

Anderson, Cary, A.;Dick, Thomas, E.;Orem,, John

doi: 10.1093/sleep/18.5.325pmid: 7676164

Summary: Clinical evidence indicates that swallowing, a vital function, may be impaired in sleep. To address this issue, we elicited swallows in awake and sleeping adult cats by injecting water through a nasopharyngeal tube. Our results indicate that swallowing occurs not only in non-rapid eye movement (NREM) sleep, but also in rapid eye movement (REM) sleep. In NREM sleep, the injections often caused arousal followed by swallowing, but, in the majority of cases, swallowing occurred in NREM sleep before arousal. These swallows in NREM sleep were entirely comparable to swallows in wakefulness. In contrast, the injections in REM sleep were less likely to cause arousal, and the swallows occurred as hypotonic events. Furthermore, apneas were sometimes elicited by the injections in REM sleep, and there was repetitive swallowing upon arousal. These results suggest that the hypotonic swallows of REM sleep were ineffective. Sleep, Swallowing, Cats, REM sleep, Arousal This content is only available as a PDF. © 1995 American Sleep Disorders Association and Sleep Research Society

Mathur,, R.;Douglas, N., J.

doi: 10.1093/sleep/18.5.330pmid: 7676165

Summary: 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. Arousals, Polysomnography, Sleep This content is only available as a PDF. © 1995 American Sleep Disorders Association and Sleep Research Society

Armitage,, Roseanne

doi: 10.1093/sleep/18.5.334pmid: 7676166

Summary: Period-analyzed electroencephalographic (EEG) activity was evaluated in 11 men and 11 women to explore the distribution of EEG frequencies during sleep and potential gender differences. Significant stage-of-sleep main effects were noted for both incidence and amplitude measures. Power measures seemed to best differentiate between non-rapid eye movement (NREM) stages, although incidence measures showed roughly the same distributions across sleep stages. Beta incidence and amplitude was highest in stage 1 sleep followed in descending order by rapid eye movement (REM), stage 2, and slow-wave sleep (SWS). Delta incidence and amplitude were highest in SWS, with slightly lower values in stage 2. Interestingly, REM was characterized by higher incidence and amplitude delta than those found in stage 1 sleep. EEG variables did not show striking sex differences in any sleep stage, although a global measure of delta power in NREM sleep was higher among women. Hemispheric asymmetries were small throughout REM and NREM stages. These findings suggest that period analysis provides a detailed description of EEG frequency characteristics during sleep but does not reveal dramatic gender differences. Computer quantification, Gender, Period analysis, Sleep EEG This content is only available as a PDF. © 1995 American Sleep Disorders Association and Sleep Research Society

Benbadis, Selim, R.;Perry,, Michael;Wolgamuth, Barbara, R.;Turnbull,, John;Mendelson, Wallace, B.

doi: 10.1093/sleep/18.5.342pmid: N/A

Summary: Since its introduction in the mid-1970s, the multiple sleep latency test (MSLT) has become the standard method for evaluating hypersomnolence. The mean sleep latency is usually calculated and constitutes the traditional basis for interpretation. Mean and median are both measures of the central tendency of a distribution, but because the trials of the MSLT are limited to 20 minutes, the median may be more appropriate. The objective of this study was to compare the value of the mean versus the median sleep latency in the interpretation of the MSLT. We retrospectively analyzed 100 MSLTs performed for evaluation of excessive daytime sleepiness. Patients’ ages ranged from 6 to 84 years (mean 43). Mean and median sleep latencies were calculated according to standard formulas. We classified each record into one of three categories, using both the mean and the median sleep latencies: normal (>10 minutes), moderate (≥5 and ≤10 minutes), and severe sleepiness (<5 minutes). Of the 100 MSLTs, 89 remained in the same category (normal, moderate, severe) whether mean or median was used. In 11 cases, the category changed. All shifts were by one category, that is, no shift occurred between normal and severe. This study suggests that, despite valid theoretical arguments for the use of the median, both measures are equally acceptable for clinical purposes. MSLT, Daytime sleepiness, Central tendency, Mean This content is only available as a PDF.

Lorenzo,, I.;Ramos,, J.;Arce,, C.;Guevara, M., A.;Corsi-Cabrera,, M.

doi: 10.1093/sleep/18.5.346pmid: N/A

Summary: 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. EEG power, Oral temperature, Reaction time, Sleep deprivation This content is only available as a PDF.

Folkard, Simon; Spelten, Evelien; Totterdell, Peter; Barton, Jane; Smith, Lawrence

doi: 10.1093/sleep/18.5.355pmid: 7676169

Summary: Current models of sleep regulation postulate both a homeostatic and circadian component and promise an understanding of disturbed and displaced sleep. Estimates of these components have traditionally required relatively cumbersome and costly measures, including sleep electroencephalograms and continuously recorded rectal temperature, but it has recently been demonstrated that they may successfully be based on frequent (e.g. 2-hourly) concurrent ratings of alertness. This paper examines whether similar results might be obtained using retrospective survey measures of alertness obtained from shiftworking nurses at a single sitting. These retrospective measures are shown to be sensitive to both time of day and shift, to have a high level of reliability even for relatively small sample sizes (e.g. 10) and to be valid predictors of more traditional concurrent measures of alertness. It is concluded that retrospective alertness ratings may prove to be an extremely cost-effective method for examining the trends in alertness in various groups, including those suffering from specific types of sleep disorder. Sleep, Circadian phase, Alertness, Shiftwork This content is only available as a PDF. © 1995 American Sleep Disorders Association and Sleep Research Society © 1995 American Sleep Disorders Association and Sleep Research Society

Reinish, Lawrence, W.;MacFarlane, James, G.;Sandor,, Paul;Shapiro, Colin, M.

doi: 10.1093/sleep/18.5.362pmid: N/A

Summary: The purpose of this study was to establish the effects of selegiline HCl on sleep parameters in narcolepsy and to contrast these effects with the effects of methylphenidate. Eleven subjects with narcolepsy were studied drug-free and while receiving selegiline (15–30 mg/day) by polysomnography. The methylphenidate-treated group consisted of 11 age-matched subjects with narcolepsy. On overnight polysomnography, compared to pretreatment values, selegiline treatment resulted in a significant increase in rapid eye movement (REM) latency (138.1 ± 62.8 vs. 48.7 ± 42.3 minutes, p < 0.05) and sleep stage changes per hour. The increase in REM latency in subjects treated with methylphenidate was marginally significant (116.9 ± 78.3 vs. 54.3 ± 23.7 minutes, p = 0.054). Maintenance of wakefulness testing during treatment revealed the methylphenidate-treated group to be significantly more alert than the selegiline-treated group (18.4 ± 1.9 vs. 9.4 ± 4.8 minutes, p < 0.001); a retrospective survey of subjects treated with selegiline found that a majority reported clinical improvement with selegiline treatment. These results suggest that selegiline should be considered for further investigation as a treatment for narcolepsy. Narcolepsy, Selegiline HCl, Methylphenidate, Sleep stages, Sleep This content is only available as a PDF.

Epstein, Lawrence, J.;Strollo, Patrick, J.;Donegan, Robert, B.;Delmar,, Judith;Hendrix,, Craig;Westbrook, Philip, R.

doi: 10.1093/sleep/18.5.368pmid: 7676171

Summary: Adenotonsillar hypertrophy has been identified as an early manifestation of human immunodeficiency virus (HIV) disease. Three patients with HIV disease were identified with obstructive sleep apnea (OSA) due to adenotonsillar hypertrophy. In order to examine the relationship between HIV-induced adenotonsillar hypertrophy and OSA, 134 patients with asymptomatic HIV disease were screened with a self-administered sleep survey designed to detect OSA and excessive daytime somnolence. Patients meeting trigger score criteria were studied with overnight polysomnography and nine additional patients were identified with OSA. The only consistent risk factor for OSA in this young and primarily nonobese population was the presence of adenotonsillar hypertrophy, found in 11 of 12 patients with OSA. Three patients had tonsillar biopsy or tonsillectomy and all displayed benign follicular lymphoid hyperplasia. Scores on the Epworth Sleepiness Scale (ESS) were significantly higher for patients with OSA, indicating a greater degree of hypersomnolence (mean ESS scores: OSA + = 11.4 ± 3.6, OSA− = 7.8 ± 4.6, p = 0.012). In our population, patients with HIV disease had a prevalence of OSA of 7%. HIV-induced adenotonsillar hypertrophy is a risk factor for the development of OSA. HIV patients with complaints of excessive daytime sleepiness and snoring who are found to have adenotonsillar hypertrophy on exam should undergo a sleep evaluation to rule out the presence of OSA. HIV, Obstructive sleep apnea, Sleep, Daytime somnolence This content is only available as a PDF. Author notes † Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S.A. © 1995 American Sleep Disorders Association and Sleep Research Society