SLEEP

Barrett,, Judith;Lack,, Leon;Morris,, Mary

doi: 10.1093/sleep/16.2.93pmid: N/A

Summary: The circadian rhythm of deep body temperature consists of both an endogenous component and evoked components resulting from exogenous influences. Previous studies of the sleep-evoked effect have failed to control confounding influences, so that the effect of sleep per se has not been established. In the present study, eight good sleepers had their rectal temperatures recorded for 24 hours in each of two laboratory conditions employing a constant routine to control exogenous influences. Sleep was allowed at night in one condition. Following sleep onset, body temperature dropped more rapidly and remained lower than when wakefulness continued over the same time, resulting in a mean sleep-evoked decrease of 0.31 ± 0.09°C. Fourier regression analysis showed a significant 24-hour (circadian) temperature rhythm, together with a 12-hour harmonic rhythm, in each condition. Circadian rhythm parameters were also altered by the sleep-evoked (or masking) effect, with the amplitude increased and the mean decreased when subjects slept at night in the constant routine. It was suggested that a constant routine methodology be used in studies of circadian rhythm differences and that Fourier regression be used in preference to simple cosine curve fitting to give a better approximation of the temperature rhythm. Circadian rhythms, Temperature rhythm, Sleep, Masking effects, Constant routine This content is only available as a PDF.

Brunner, Daniel, P.;Dijk,, Derk-Jan;Borbély, Alexander, A.

doi: 10.1093/sleep/16.2.100pmid: 8446828

Summary: The effect of repeated partial sleep deprivation on sleep stages and electroencephalogram (EEG) power spectra during sleep and wakefulness was investigated in nine healthy young subjects. Three baseline nights of 8 hours (2300–0700 hours) were followed by four nights with 4 hours of sleep (2300–0300 hours) and three recovery nights of 8 hours (2300–0700 hours). Sleep restriction curtailed sleep stages 1 and 2 as well as rapid eye movement (REM) sleep, but left slow wave sleep largely unaffected. In the first two recovery nights, total sleep time and REM sleep were enhanced, and sleep latency was shortened. Slow wave sleep was increased only in the first recovery night. In accordance with the prediction of the two-process model of sleep regulation, slow wave activity (SWA; spectral power density in the 0.75–4.5-Hz range) in nonrapid eye movement (NREM) sleep increased by approximately 20% in the first night following sleep restriction, remained at this level in the subsequent 3 nights and decreased immediately after the first recovery night. In contrast to these immediate changes, progressive and more persistent changes were seen in the EEG activity of higher frequencies. Thus, activity in the upper delta band tended to gradually increase from night to night during the sleep restriction period, whereas after an initial increase, activity in the theta-alpha band changed in the opposite direction. The progressive changes were also present in the EEG spectra of REM sleep and wakefulness. Because the time course of these changes paralleled the cumulative deficit in REM sleep, they may represent a correlate of REM sleep pressure. Sleep deprivation, REM sleep, Slow wave activity, Spectral analysis, Homeostasis, Two-process model This content is only available as a PDF. Author notes * Present address: Psychiatric University Clinic, Wilhelm Klein-Strasse 27, CH-4025 Basel, Switzerland. © 1993 American Sleep Disorders Association and Sleep Research Society

Valencia-Flores,, Matilde;Campos, Rosa, Ma.;Méndez,, José;Haro,, Reyes;Schenkel,, Elizabeth;Bliwise,, Donald;Guilleminault,, Christian

doi: 10.1093/sleep/16.2.114pmid: 8446829

Summary: Sleep disturbance and the tendency to sleep during the day were assessed polysomnographically in 31 elderly women (mean age = 76.7 ± 3.6 SD) recruited from a senior citizen's living facility without reference to sleep—wake complaints. The data showed that the level of sleepiness during the day in each subject depended in part on the severity of her respiratory disturbance. It was found that the group (n = 7) of elderly females with apnea and hypopnea index (AHI) higher than 20 was more sleepy [multiple sleep latency test (MSLT) = 7.9 ± 2) than the group (n = 10) with AHI >5 but less than 20 (MSLT = 12.7 ± 5). Nevertheless, the presence and severity of respiratory disturbance were not the only factors that influenced the level of sleepiness during the day in the studied sample. A subgroup of four elderly females showed a marked sleepiness during the four tested periods (MSLT = 5.2 ± 0.6) with a very low respiratory disturbance index (AHI = 5.5 ± 0.8). Aging, Sleepiness, Sleep pathology, Multiple sleep latency test, Sleep apnea This content is only available as a PDF. © 1993 American Sleep Disorders Association and Sleep Research Society

Hoffstein,, V.;Szalai, J., P.

doi: 10.1093/sleep/16.2.118pmid: N/A

Summary: We examined the predictive value of history and physical examination in the diagnosis of obstructive sleep apnea (OSA) syndrome. This was achieved by studying a set of 594 patients referred to the sleep clinic because of suspicion of sleep apnea. All patients were asked a set of standard sleep-related questions and all had nocturnal polysomnography. We used stepwise multiple linear regression analysis to examine the relationship between the apnea/hypopnea index (AHI), defined as the number of episodes of cessation of breathing per hour of sleep (dependent variable), and age, sex, body mass index (BMI) and replies to the sleep questionnaire (independent variables). We found that age, sex, body mass index, bed partner observation of apnea and pharyngeal examination were significant predictors of AHI, explaining 36% of the variability. Subjective impression of the examining clinician was also an independent significant predictor of AHI, accounting for 10% of the variability. Using a conventional cutoff value of 10 to divide patients into apneics (AHI > 10) and nonapneics (AHI ≤ 10), the sensitivity of subjective impression was 60% and the specificity 63%. We conclude that although clinical features obtained during history and physical examination explain a relatively high percent of the variability in AHI, subjective clinical impression alone is not sufficient to reliably identify patients with or without sleep apnea. Obstructive sleep apnea, Clinical features, Predictive model This content is only available as a PDF.

Henry, George, K.;Satz,, Paul;Heilbronner, Robert, L.

doi: 10.1093/sleep/16.2.123pmid: 8446831

Summary: Body temperature, vigilance, memory, information processing and motor function were examined in 10 unmedicated narcoleptics and 10 matched controls at four different times of day. Time of day and body temperature were not related to performance. Narcoleptics displayed selective cognitive deficits in response latency, word recall, and estimation of frequency. Narcoleptics did not differ from controls in motor speed, vigilance, information processing speed or decision-making accuracy. We propose that a perceptual-encoding deficit may underlie the problems in memory and complex reaction time associated with narcolepsy. Narcolepsy, Perceptual encoding This content is only available as a PDF. © 1993 American Sleep Disorders Association and Sleep Research Society

Waters, William, F.;Adams, Serrhel, G.;Binks,, Paul;Varnado,, Paula

doi: 10.1093/sleep/16.2.128pmid: 8446832

Summary: This study investigated the relation of negative emotions, attention and stress to sleep parameters in insomniacs. It also assessed whether sleep-onset insomniacs differ from sleep-maintenance/mixed insomniacs in the relations of these variables to sleep parameters. Fourteen sleep-onset insomniacs, 13 sleep-maintenance or mixed insomniacs and 13 normal sleepers were recruited using two sequential questionnaires. The groups differed significantly on diagnostically relevant sleep parameters, assessed over 1 week by sleep diary. After completing standard anxiety, anger and depression inventories, subjects participated in two laboratory procedures during which electrophysiological responses were recorded: orienting response habituation and emotional stress elicitation. The 28 significant correlations of sleep parameters with emotion, habituation and stress measures averaged r = 0.415. In multiple regression analyses, emotion, attention and stress variables accounted for an average of 41% of the variance in sleep parameters (mean R = 0.64). Discriminant function analysis using these variables correctly classified 66% of the subjects into the three groups. It was concluded that negative emotions, stress responsiveness and attentional factors interact to influence insomnia. Negative emotion, Emotional stress, Attention/orienting response habituation, Sleep-onset insomnia, Sleep-maintenance insomnia This content is only available as a PDF. © 1993 American Sleep Disorders Association and Sleep Research Society

Terstegge,, K.;Henkes,, H.;Scheuler,, W.;Hansen, M., L.;Ruf,, B.;Kubicki,, St.

doi: 10.1093/sleep/16.2.137pmid: 8446833

Summary: Fifteen patients aged between 26 and 55 years with the acquired immunodeficiency syndrome (AIDS) and various cerebral manifestations of the disease underwent an all-night sleep electroencephalogram (EEG) registration. The recordings of 15 age-matched volunteers were examined as controls. Sleep stages were determined visually and the following spectral analysis was based on corresponding artifact-free 40-second periods. The sampling rate was 64 second−1, the spectral resolution was 0.25 Hz and the frequency ranged from 0.25–24 Hz. The power density spectra of eight EEG derivations (left and right frontopolar, frontal, central and occipital; reference montage to the ipsilateral Cb electrodes) and the coherence spectra of interhemispheric (interfrontal, interoccipital) and intrahemispheric (frontooccipital, left and right) channel pairs were computed. The power density of the patients in the 11.5–13-Hz frequency range of nonrapid eye movement (NREM) sleep was considerably lower than that of the controls (p < 0.05 and p < 0.01 at left and right frontal derivations, two-tailed Mann-Whitney U test). The power density of rapid eye movement (REM) sleep showed no consistent differences between the two groups. The interfrontal coherence of the whole frequency range below 12 Hz was markedly lower in the patient group. This applied to NREM sleep and also to REM sleep (p < 0.01 and p < 0.001 for different frequency bands between 1 and 12 Hz in NREM and REM sleep). Possible relations to clinical features are discussed. Electroencephalography, Sleep, HIV infection, Neuro-AIDS, HIV encephalitis, cerebral toxoplasmosis This content is only available as a PDF. © 1993 American Sleep Disorders Association and Sleep Research Society

, van Hilten, J. J.;Braat, E. A., M.;, van der Velde, E. A.;Middelkoop, H. A., M.;Kerkhof, G., A.;Kamphuisen, H. A., C.

doi: 10.1093/sleep/16.2.146pmid: 8446834

Summary: The aim of this study was to assess the internight and intrasubject variability of nocturnal activity and immobility measures of 99 healthy subjects aged 50–98 years. Motor activity was recorded at home during 6 successive nights with a wrist-worn activity monitor. The occurrence of suprathreshold motor activity was recorded over 15-second epochs. For each subject, six mean measures reflecting activity or immobility during sleep and their coefficient of variation were calculated. Our results revealed no first-night effect or day-of-week effect of the activity and immobility measures over the 6 nights across all subjects. On the other hand, for all nocturnal activity and immobility measures, a considerable intrasubject variability across the 6 nights was found. Females had a greater intrasubject variability of the mean duration of immobility periods and the movement index than males. The intrasubject variability of all nocturnal activity and immobility measures across the successive age groups remains stable. These findings emphasize that although a first-night effect may be lacking, the intrasubject variability of activity and immobility measures across several nights may still be considerable. Activity monitoring, Sleep, Internight and intrasubject variability This content is only available as a PDF. © 1993 American Sleep Disorders Association and Sleep Research Society

Brooks, John O.; Friedman, Leah; Bliwise, Donald L.; Yesavage, Jerome A.

doi: 10.1093/sleep/16.2.151pmid: 8446835

Summary: Measures derived from the wrist actigraph have been found to correlate highly with EEG measures of normal sleep. Although the actigraph has been used to study normal sleep, few studies have used the actigraph as a measure of sleep of elderly insomniacs. The present study, which used elderly insomniacs, sought to investigate the sensitivity of the actigraph to detect the effects of an insomnia treatment. The actigraph was sufficiently sensitive to detect the effect of the sleep restriction therapy used on several sleep measures. Subsidiary analyses suggested that the sleep log, although not an accurate measure of sleep, may be useful as a measure of elderly insomniacs' subjective perception of sleep. Because the actigraph can be used more easily and less expensively than the polysomnogram, the actigraph appears to be a promising measure for assessing the efficacy of treatment interventions in elderly insomniacs. Actigraph, Insomnia, Aging This content is only available as a PDF. © 1993 American Sleep Disorders Association and Sleep Research Society © 1993 American Sleep Disorders Association and Sleep Research Society

Nofzinger, Eric, A.;Fasiczka, Amy, L.;Thase, Michael, E.;Reynolds, Charles, F.;Frank,, Ellen;Jennings, J., Richard;Garamoni, Gregory, L.;Matzzie, Jeanette, V.;Kupfer, David, J.

doi: 10.1093/sleep/16.2.156pmid: N/A

Summary: The study of nocturnal penile tumescence (NPT) is frequently used to evaluate male erectile dysfunction. Buckling force, a measure of rigidity, is an important part of this evaluation, but its reliability is unknown. Accordingly, we studied the reliability of buckling force measurement and the stability of “maximum buckling force” between consecutive NPT series repeated in the same subject. For individual subjects, we correlated buckling forces for separate episodes of sleep-related tumescence that were of comparable fullness (0–100%) as rated by a technician's visual estimates. For healthy control subjects, test-retest correlations were >0.8 both within-night and across study series separated by an average of 70 weeks. In depressed men, correlations within nights were >0.9, but fell to 0.64 across study series separated by an average of 21 weeks. Despite the high reliability of buckling force measurement, we found little stability of “maximum buckling force” between NPT series for individual subjects. Considerable variability in the maximum degree of penile rigidity was seen over time despite a constant level of reported daytime erectile function. We conclude that although penile rigidity is one of the more important variables in the assessment of male erectile dysfunction and can be measured reliably, the instability of maximum rigidity during sleep-related erections suggests that it is, at best, an imprecise correlate of daytime erectile function. Nocturnal penile tumescence, Buckling force This content is only available as a PDF.