SLEEP

Tobler,, Irene

doi: 10.1093/sleep/15.1.1pmid: N/A

Summary Sleeping behavior was investigated during 294 nights for female Asian elephants (circus: n = 7; zoo: n = 5; including an infant). The animals were recorded continuously on time-lapse video tapes for 7-16 days consecutively. Seasonal changes in sleep behavior were studied by comparing summer (16-day) and winter (13-15day) recordings; and sleep development was assessed by recording a mother and her infant for three consecutive nights per month for 15 months (age 5-19 months). Sleep occurred in a recumbent (RS) and in a standing position (standing sleep: SS). Although signs of paradoxical sleep (PS) were often evident, the exact onset and end of a PS episode could not be determined. Sleep onset occurred after 2100 hours, and sleep increased progressively reaching a maximum between 0100 and 0400 hours. Total sleep time (TST) in the adults comprised 4.0-6.5 hours per night (including 13.8-130.9 minutes of SS) and did not differ between the two groups. Seasonal differences were present in TST and in the distribution of sleep within the night; more sleep occurred in the winter. The duration of RS episodes in the adults was 72.0 minutes, a value far below the sleep-cycle length of 124 minutes that others have reported for elephants. TST in the infant decreased during the course of the 15-month recording period from 8.1 hours to 5.1 hours. SS occurred for the first time at the age of 9 months. Elephant, Sleep cycle− Development, Seasonality This content is only available as a PDF.

Landis, Carol, A.;Bergmann, Bernard, M.;Ismail, M., Mokhtar;Rechtschaffen,, Allan

doi: 10.1093/sleep/15.1.13pmid: 1557590

Summary: Previous studies of total sleep deprivation (TSD) and paradoxical sleep deprivation (PSD) in the rat by the disk-over-water method have indicated that both produce changes in thermoregulation. In both kinds of deprivation, there was a progressive, large increase in heat production as indicated by measures of energy expenditure (EE). In TSD there was an initial increase in waking body temperature (Tb) followed by a later decrease; in PSD there was only a progressive decrease. The increases in heat production far in excess of heat storage indicated increased heat loss in both groups. Because the increase in Tb in TSD rats was supported by ambient temperature choices (Tch) in a thermal gradient that became progressively higher during deprivation, an increase in waking temperature setpoint (TSET) was indicated. Because the rats resorted to behavioral warming in spite of greatly increased thermogenesis, they must have had some failure to retain body heat. Prior to the present study, changes in TSET, had not been evaluated in PSD rats. Because they had not shown increases in Tb, PSD rats might not have an elevated TSET, which would indicate a functional difference between PS and nonrapid eye movement (NREM) sleep. Also, an evaluation of behavioral thermoregulation in PSD rats would clarify whether their Tb decline resulted from excessive heat loss or from a lowered TSET. To evaluate changes in heat flow and TSET, EE, Tb and Tch were measured in five PSD rats and their yoked control (PSC) rats. PSD rats showed progressive increases in EE and decreases in Tb as in the earlier PSD study; Tch rose progressively. PSC rats showed minimal changes in all three parameters. Because PSD rats showed increased EE and Tch, which oppose Tb decline, their decline in Tb must be ascribed to excessive heat loss rather than to decreased thermogenesis or a lowered TSET. Heat loss deficits and TSET change in PSD rats were compared to those of previously studied TSD rats. A positive correlation between EE and Tch in both groups was consistent with an elevation of thermogenesis and behavioral warming in response to a heat retention deficit. At Tch near baseline, where Tb was assumed to be near TSET, Tb was increased in TSD rats but not in PSD rats, indicating that TSET was increased by TSD and not by PSD. Therefore, in TSD rats the increased Tch and EE may be viewed as attempts to reach an elevated TSET in the face of excessive heat loss. In PSD rats, elevated Tch and EE are also responses to excessive heat loss, but the apparent target is to maintain baseline Tb rather than an elevated TSET. Because both TSD and PSD rats lost PS, but NREM sleep was well preserved in PSD, the elevation of TSET in TSD rats was more closely associated with the loss of NREM sleep, whereas the difficulty in retaining body heat can be ascribed to the loss of PS. Sleep deprivation, Paradoxical sleep deprivation, Temperature setpoint, Thermal preference, Heat loss, Energy consumption, Temperature regulation This content is only available as a PDF. © 1992 American Sleep Disorders Association and Sleep Research Society

Follenius,, M.;Brandenberger,, G.;Bandesapt, J., J.;Libert, J., P.;Ehrhart,, J.

doi: 10.1093/sleep/15.1.21pmid: 1557591

Summary: The relationship between the temporal organization of Cortisol secretion and sleep structure is controversial. To determine whether the Cortisol profile is modified by 4 hours of sleep deprivation, which shifts slowwave sleep (SWS) episodes, 12 normal men were studied during a reference night, a sleep deprivation night and a recovery night. Plasma Cortisol was measured in 10-minute blood samples. Analysis of the nocturnal Cortisol profiles and the concomitant patterns of sleep stage distribution indicates that the Cortisol profile is not influenced by sleep deprivation. Neither the starting time of the Cortisol increase nor the mean number and amplitude of pulses was significantly different between the three nights. SWS episodes were significantly associated with declining plasma Cortisol levels (p < 0.01). This was especially revealed after sleep deprivation, as SWS episodes were particularly present during the second half of the night, a period of enhanced Cortisol secretion. In 73% of cases, rapid eye movement sleep phases started when Cortisol was reflecting diminished adrenocortical activity. Cortisol increases were not concomitant with a specific sleep stage but generally accompanied prolonged waking periods. These findings tend to imply that cortisol-releasing mechanisms may be involved in the regulation of sleep. Cortisol, Sleep structure, Slow-wave sleep, Sleep deprivation This content is only available as a PDF. © 1992 American Sleep Disorders Association and Sleep Research Society

Moline, Margaret, L.;Pollak, Charles, P.;Monk, Timothy, H.;Lester, Laurie, S.;Wagner, Daniel, R.;Zendell, Steven, M.;Graeber, R., Curtis;Salter, Charles, A.;Hirsch,, Edward

doi: 10.1093/sleep/15.1.28pmid: 1557592

Summary: Six healthy young men and eight early middle-aged men were isolated from environmental time cues for 15 days. For the first 6–7 days (one or two nights adaptation, four nights baseline), their sleep and meals were scheduled to approximate their habitual patterns. Their daily routines were then shifted 6 hours earlier by terminating the sixth or seventh sleep episode 6 hours early. The new schedules were followed for the next 8 or 9 days. Important age-related differences in adjustment to this single 6-hour schedule shift were found. For the first 4-day interval after the shift, middle-aged subjects had larger increases of waking time during the sleep period and earlier termination of sleep than young subjects. They also reported larger decreases in alertness and well-being and larger increases in sleepiness, weariness and effort required to perform daily functions. The rate of adjustment of the circadian core temperature rhythm to the new schedule did not differ between groups. These results suggest that the symptoms reported by the middle-aged subjects may be due mainly to difficulty maintaining sleep at early times of the circadian day. The compensatory response to sleep deprivation may also be less robust in middle-aged individuals traveling eastbound. Jet lag, Sleep, Circadian rhythms, Aging This content is only available as a PDF. © 1992 American Sleep Disorders Association and Sleep Research Society

Schechtman, V., L.;Harper, R., M.

doi: 10.1093/sleep/15.1.41pmid: N/A

Summary Coordination of cardiac and respiratory measures is not mature in newborn infants but develops during early life. The course of that development is assessed in this study. Twelve-hour recordings of electrocardiogram, electroencephalogram, digastric electromyogram, electrooculogram and expired C02 were obtained from 25 normal infants at 1 week and 1, 2, 3, 4 and 6 months of age. Each 1-minute epoch was classified as quiet sleep, rapid eye movement (REM) sleep, waking or indeterminate state. In each sleep−waking state, the correlations of heart rate with respiratory rate, heart rate with respiratory rate variability and respiratory rate with its own variability were determined on a minute-by-minute basis for each recording. The relative extents of correlations between measures and the maturational trends of these correlations were profoundly influenced by sleep−waking state. During quiet sleep, two of the three correlations weakened significantly over the first month of life, but, in the waking state, the same correlations strengthened over this period. During quiet sleep and waking, the three correlations showed similar patterns of development, but the three showed dissimilar developmental trends during REM sleep. These dissimilarities may reflect changes in the nature of REM sleep consequent to myelination of rostral brain pathways. Heart rate, Infants, Respiration, Sleep This content is only available as a PDF.

Ditta, S., D.;George, C. F., P.;Singh, S., M.

doi: 10.1093/sleep/15.1.48pmid: N/A

Summary Restriction fragment length polymorphism (RFLP) associated with the three human lenkocyte antigen (HLA)-D-region gene-specific cDNA probes (gene-specific DQα, DQβ and DPβ) was evaluated in two Caucasian families from southwestern Ontario, each with two confirmed narcoleptic siblings. The special feature of the two families is that the affected members are not necessarily DRwl5 (previously DR2) positive. In family 1, of the two affected sibs one is DRwl5 positive, whereas in family 2 all members including the two affected sibs are DRwl5 negative. There is no association between narcolepsy and HLA haplotype in the two families. Further, the polymorphic DNA band patterns generated by a number of restriction enzymes do not show a relationship with the presence or absence of narcolepsy. The probe-specific DNA band patterns however do follow the HLA haplotypes associated with the DQ and DR loci. These results suggest that in DRw15-negative narcolepsy, the DNA patterns are not informative with respect to diagnosing or predicting the presence of narcolepsy. Further, such results argue for genetic heterogeneity in narcolepsy, and the role of DRw15 in the development of the disease could at best be viewed as contributory and not essential. DRwl5 negative, Narcolepsy, DNA, RFLP This content is only available as a PDF.

Downey,, Ralph;Bonnet, Michael, H.

doi: 10.1093/sleep/15.1.58pmid: 1557594

Summary: Subjective insomniacs overestimate sleep latency at the beginning of their nocturnal sleep period. It was hypothesized that subjective insomniacs could be trained to accurately estimate sleep latency by learning to differentiate wakefulness from sleep. Ten subjective insomniacs were randomly assigned to one of two groups. Group 1 subjects participated in both a control and a training week; group 2 subjects participated only during a training week. Each week consisted of a baseline lab night, a training lab night (treatment or control), a home (unmonitored night) and a recovery lab night. During training, subjects were taught to use sleep markers (A, B or C) to help them more accurately estimate sleep latency and were given feedback about the accuracy of their estimates. Marker A corresponded to an electroencephalographic level of wakefulness; marker B corresponded to the initial sleep spindle; marker C corresponded to 5 minutes of continuous sleep after the first sleep spindle. In the control condition, subjects had no feedback and were not taught to use markers to help them judge sleep from wakefulness. Total sleep time and percent stage 3 sleep increased, and objective sleep latency decreased on recovery nights. After training, subjective sleep latency, correctness of estimates of sleep versus wakefulness and perceived ability to fall asleep significantly improved. This study helps to establish that subjective insomniacs can learn to more accurately estimate sleep from wakefulness with the use of sleep-wake markers. Sleep, Sleep disorders, Insomnia, Subjective insomnia, Behavior This content is only available as a PDF. © 1992 American Sleep Disorders Association and Sleep Research Society

Terzano, Mario, Giovanni;Parrino,, Liborio

doi: 10.1093/sleep/15.1.64pmid: 1557595

Summary: In nonrapid eye movement (NREM) sleep, electroencephalographic cyclic alternating patterns (CAPS) express the organized complexity of arousal-related phasic events. As a translation of sustained instability of the arousal level, CAPS increase under perturbation and decrease under sleep-promoting conditions. After adaptation to the sleep lab, 18 subjects (12 with persistent psychophysiological insomnia and 6 without sleep complaints), all aged 40–60 years, underwent a random sequence of two nonconsecutive nocturnal recordings, one under placebo and one under an imidazopyridine hypnotic agent (Zolpidem). The choice of this drug was oriented by its capability to warrant, at the selected dose of 10 mg, a physiological profile of sleep. Polysomnographic parameters and selfreport of sleep quality by means of visual analogue scale (VAS) were assessed by analysis of variance followed by a Scheff test when F statistics were significant. The placebo nights of controls showed a significantly longer duration of total sleep time (+ 60 minutes) compared with the placebo nights of insomniacs. However, no relevant differences emerged from the other traditional polysomnographic variables. Conversely, CAP rate (CAP time × 100/NREM sleep time) showed highly sensitive and consistent modifications. Under placebo, CAP rate was significantly higher among insomniacs compared with controls (62.2% vs. 38.5%). Under medication, CAP rate dropped to 26.8% in insomniacs, whereas it was only moderately reduced in controls (31%). CAP rate values paralleled the self-rating estimation of sleep quality, but the VAS means differed significantly only among insomniacs where a sharp average fall from 45 mm (placebo nights) to 15 mm (Zolpidem nights) could be detected. Our findings suggest that CAP rate in sleep analysis can represent a useful tool for the diagnosis of insomnia and for gaining insight into the therapeutic efficacy of hypnotic-sedative drugs. Sleep, Insomnia, Polysomnography, Cyclic alternating pattern, Hypnotics, Zolpidem This content is only available as a PDF. © 1992 American Sleep Disorders Association and Sleep Research Society

McCall, W., Vaughn;Edinger, Jack, D.

doi: 10.1093/sleep/15.1.71pmid: N/A

Summary Sleep state misperception (SSM) is the diagnostic term proposed in the International Classification of Sleep Disorders to describe those insomniacs who mislabel their sleep as wakefulness. Although sleep misperception has long been recognized among insomnia patients, it is debatable whether this clinical finding warrants a distinctive diagnosis or simply represents an extreme variation of other, more common forms of insomnia. We present two cases to explore the clinical meaningfulness of SSM. It is concluded that SSM represents a distinctive, albeit rare, sleep disorder. However, refinements in existing diagnostic criteria may be needed to improve the meaningfulness of the SSM diagnosis. Sleep state misperception, Insomnia patients This content is only available as a PDF.

Bendtson,, Inger;Gade,, John;Thomsen, Carsten, E.;Rosenfalck,, Annelise;Wildschiødtz,, Gordon

doi: 10.1093/sleep/15.1.74pmid: 1557597

Summary: Eight insulin-dependent diabetic patients were studied to evaluate sleep patterns during normoglycemia and spontaneous and insulin-induced hypoglycemia. Two channels of electroencephalogram (EEG), electromyogram and actooculogram were recorded. The signals were analyzed off-line, using a polygraphic sleep analysis system. The scoring was mainly based on the color density spectral array of the EEG. Blood glucose and growth hormone were measured serially. Asymptomatic, spontaneous nocturnal hypoglycemia occurred in 38% of the nights. Conventional sleep analysis showed a tendency toward prolongation of the two first rapid eye movement cycles on hypoglycemic nights, although it was insufficient to explain the activities seen during hypoglycemia. Blood glucose values below 2.0 mmol/1 were observed in some of the patients accompanied by EEG changes with increased theta and delta activity. Hypoglycemia, Diabetes, Sleep, Color density spectral array, Growth hormone This content is only available as a PDF. © 1992 American Sleep Disorders Association and Sleep Research Society