SLEEP

Chammas, Dany Zaatar; Magana, Omar; Krilowicz, Beverly L.

doi: 10.1093/sleep/22.3.284pmid: 10341378

Summary:Study Objectives: Various ablation studies have implicated the posterior basal diencephalon in the promotion of wake-fulness. Although many studies have examined the role of this structure in promotion of cortical arousal, few investigations have attempted to examine its importance in regulation of motor activation (behavioral arousal). In the current study, recordings of freely moving decerebrate rats with and without a posterior basal diencephalon were performed. These studies allowed determination of the behavioral states expressed by the preparations and whether removal of the posterior basal diencephalon completely eliminated expression of both activated state with and activated state without limb movements. Design: Muscle activity was recorded from limb and neck muscles. Eye movements and heart rate were also monitored. The percentage of time spent in various behavioral states and the proportion of limb movements expressed in each of these states were determined. Measurements and Results: Rats with an intact posterior basal diencephalon cycled between all behavioral states. However, they spent most of the recording time in an activated state. In contrast, removal of the posterior basal diencephalon produced rats that spent most of the recording period in a quiescent state. Limb movements were expressed mainly by animals with an intact posterior basal diencephalon, and only when these animals were in the activated state. Conclusions: The results of this study suggest that the posterior basal diencephalon is required for expression of an activated state and specifically provide evidence for a descending projection from this region required for expression of this state and associated motor activation.

Picchietti, Daniel L.; Walters, Arthur S.

doi: 10.1093/sleep/22.3.297pmid: 10341379

Summary:The purpose of this study is to review clinical features of children with moderate to severe Periodic Limb Movement Disorder (PLMD). Because of our interest in both Restless Legs Syndrome (RLS) and Attention-Deficit Hyperactivity Disorder (ADHD), many of our patients had one or both of these conditions. We did a retrospective review of 129 children and adolescents who were found to have Periodic Limb Movements in Sleep (PLMS) >5/hour of sleep. Sixty five had PLMS of 5–10/hour of sleep, 48 had PLMS of 10–25/hour of sleep and 16 had PLMS>25/hour of sleep. One hundred and seventeen of the original 129 had ADHD. Stimulant medication did not seem to play a role in the production of PLMS. In only 25 of the 129 cases did parents note the presence of PLMS before being specifically asked to look, and even after specific instructions to look, PLMS were not noted by the parents in 39 patients. The sub-group of 16 children and adolescents—6 female, 10 male (average age 11.1 years—range 6–17 years) with moderate to severe PLMS >25/hour of sleep are described in more detail. Fifteen of the 16 patients had ADHD. Four of the 16 had RLS and 10 of 13 patients for whom a family history was available had a parent with RLS. Two of the 16 patients had their PLMS initially misdiagnosed as seizures. Sleep disturbance was present in all 16 patients and 7 of the 16 had daytime somnolence which resolved with dopaminergic medications. To our knowledge this is the first clinical series of moderate to severe PLMS in children and adolescents to be fully described in the literature.

McGraw, Kate; Hoffmann, Robert; Harker, Chris; Herman, John H.

doi: 10.1093/sleep/22.3.303pmid: 10341380

Summary:The development of circadian rhythms in a human infant Study Objectives—This study examines the ontogeny and interaction of circadian rhythms of sleep, wake, temperature, melatonin, and feeding in the human newborn, and the influence of photic and non-photic factors on the initiation of entrainment. Design—An infant's sleep-wake state, temperature, and salivary melatonin were monitored from birth to 6 months. Temperature was obtained every hour, and the infant's sleep/eating onset/termination were observed continuously and recorded until day 182. Salivary melatonin was obtained weekly for a 24-hour period, starting at week 3. Setting—The infant slept in his parents’ bedroom. All household members awakened, retired, and ate meals according to a fixed schedule during the study, while the infant ate, slept, and woke on demand. Participants—A healthy male infant was the subject. Biological parents gathered data continuously for six months. Interventions—The infant's schedule was on-demand; the household's was fixed. Illumination was restricted to sunlight. Measurements and Results—The circadian rhythm of temperature appeared first, soon after birth, and became statistically significant within one week. The wake circadian rhythm appeared second, attaining significance at day 45; approximately the same time that increased melatonin concentration began to occur at sunset. The sleep circadian rhythm appeared last, attaining significance after day 56. Ninety to 120 minute zones of sustained wakefulness first appeared in the second month of life subsequent to awakening and prior to sleep onset. The infant's nocturnal sleep-onset was coupled to sunset before day 60 and subsequently to family bedtime, giving evidence of initial photic entrainment followed by social entrainment. Conclusions—Circadian rhythms appeared much more rapidly in this infant than previously reported; their rapid appearance was probably facilitated by maximal exposure to sunlight, and regular social cues. These lighting conditions replicate universal infant experience prior to the invention of artificial light.

Fletcher, Adam; Heuvel, Cameron van den; Dawson, Drew

doi: 10.1093/sleep/22.3.313pmid: 10341381

Summary:Previous studies have inferred a relationship between core temperature and sleep disruption from manipulations of core temperature such as heating prior to sleep or administration of hyperthermic substances. To examine the relationship more directly, this study aimed to produce a direct increase in core temperature during the sleep period. Following an adaptation night, 16 subjects underwent counter-balanced baseline and experimental conditions, on non-consecutive nights between 1900 and 0800h. In the experimental condition, subjects were heated between 0230h and wake up, which significantly increased mean core temperature from baseline levels between 0400 and 0700h by 0.18±0.03 °C (mean±SEM, p<0.05). This increase in core temperature was associated with a significant decrease in sleep efficiency between 0330 and 0730h of 5.5 ± 0.9% (mean ± SD, p < 0.05). Polysomnographic measures indicated a significant increase in the number of stage changes and the amounts of stage 0 and stage 1 sleep (p<0.05). Other stages of sleep and the number and duration of arousals were not significantly effected by heating. There was a strong trend toward and increase in the number of arousals (p=0.054), however, core body temperature did not increase across arousals. Also, melatonin output was not effected by heating. Taken together, these results suggest that increased nocturnal core temperature alone may disrupt sleep. Additionally, the results support evidence suggesting that the circadian regulation of the sleep/wake cycle may be mediated via core temperature.

McNamara, Frances; Wulbrand, Henning; Thach, Bradley T.

doi: 10.1093/sleep/22.3.320pmid: N/A

Summary:Study Objectives—Arousal is considered to be an important protective response in a sleeping infant and its depression could leave an infant vulnerable to a life threatening stimulus. We found previously that arousal to a non-respiratory (tactile) stimulus occurs in a sequence of events that begins with spinal, followed by brainstem responses, and then a cortical electroen-cephalographic (EEG) arousal response. We hypothesized that repeated stimuli would depress the arousal responses by habituation and that spinal and brainstem responses would be more resistant to habituation than cortical responses. Participants—We studied 22 normal infants. Interventions—The infants underwent polysomnographic monitoring during a daytime nap. Tactile stimuli was applied to the infants foot at 5-second intervals. Measurements and Results—We found that spinal, brainstem, and cortical responses occurred on the first trial of each test. Repeated trials during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep resulted in a decrease in the incidence of each individual response and eventually elimination of the arousal responses. Cortical responses were eliminated first, followed by brainstem responses and finally spinal responses. The elimination of each of the responses occurred more rapidly during REM sleep than during NREM sleep. Conclusions—Habituation of the infant arousal sequence occurs with repeated tactile stimulation. There is a serial habituation of responses from the cortical to the spinal level, which occurs more rapidly during REM sleep. Rapid habituation to innocuous stimuli is probably beneficial in avoiding detrimental sleep disruptions. However, in situations requiring the protective functions of arousal, such habituation could be detrimental to an infant.

Binks, Paul G.; Waters, William F.; Hurry, Mark

doi: 10.1093/sleep/22.3.328pmid: 10341383

Summary:Previous research has shown that total sleep deprivation produces impairment in sustained attention and vigilance especially if the deprivation period is greater than 48 hours. However little is known about the effects of sleep deprivation on performance of tasks considered to be measures of higher cortical functioning such as tests of cognitive flexibility and the capacity to shift from one response set to another. One current hypothesis is that sleep deprivation of a shorter duration (34–36 hours) adversely affects higher cortical function while effects on attention and vigilance tasks are relatively mild. Performance on an intelligence test, a test of sustained attention and tests designed to measure higher cortical function were compared in a group of 29 subjects who underwent 34–36 hours of continuous sleep deprivation and 32 normal sleeping control subjects. No significant group performance differences in the hypothesized direction were noted on any measure. One night of total sleep deprivation does not appear to impair performance on tasks that are designed to assess higher cortical functioning.

Devoto, Alessandra; Lucidi, Fabio; Violani, Cristiano; Bertini, Mario

doi: 10.1093/sleep/22.3.336pmid: 10341384

Summary:This study evaluated the effects of different amounts of sleep and SWS restriction on the ensuing day-time sleepiness. Six healthy selected males, after one adaptation night and an initial 8-hr baseline night, were allowed to sleep 5, 4, 3, 2, and 1 hr with a 1-week interval between conditions. The following day, 4 sleep onset MSLT trials and 2 Wilkinson Auditory Vigilance Task (WAVT) were administered. Before each MSLT, self evaluations of sleepiness and activation on a visual analogue scale (ADAS) were assessed. Each restriction night was followed by an 8-hr recovery night, and a final 8-hr baseline night was recorded. The day after each night the same diurnal tests were repeated. Results indicated a linear increase in the propensity to sleep (MSLT) and of subjective sleepiness as a function of the increase in sleep restrictions. Performance scores (WAVT) showed that vigilance is partially affected by sleep restrictions. For each measure, regression analyses showed that the effect of sleep reduction is better predicted by the total duration of sleep than by the amount of SWS. Correlations between measures were negligible with the exception of those between performance and subjective sleepiness measures.

Mignot, Emmanuel; Young, Terry; Lin, Ling; Finn, Laurel

doi: 10.1093/sleep/22.3.347pmid: N/A

Summary:Narcolepsy, a neurological disorder characterized by excessive daytime sleepiness and abnormal REM sleep, is known to be tightly associated with the Human Leukocyte Antigen (HLA) DQ allele DQB1*0602. In this study, we have explored the possibility that normal subjects carrying this HLA allele (25% of the general population) could display subclinical REM sleep abnormalities and increased daytime sleepiness. Data from 525 middle-aged adults enrolled in the Wisconsin Sleep Cohort study were used for this analysis. Nocturnal polysomnography, sleep latency during the multiple sleep latency test (MSLT), and questionnaire items pertaining to excessive daytime sleepiness were compared between DQB1*0602 positive (n=132) and negative (n=393) participants. Results indicate shorter REM latency whether or not the latency was adjusted for wake after sleep onset (p=0.003 and p=0.02 respectively), increased sleep efficiency (p=0.06) and decreased percent time spent in stage I sleep (p=0.02) during nocturnal polysomnography in DQB1*0602 subjects. Data gathered using the Multiple Sleep Latency Test or the Epworth and Stanford sleepiness scales did not differentiate between DQB1*0602 positive and negative subjects. These results support the hypothesis that polymorphisms at the level of HLA DQ modulates sleep tendencies in humans.

Aikens, James E.; Mendelson, Wallace B.

doi: 10.1093/sleep/22.3.355pmid: 10341386

Summary:Study Objective—To compare the MMPI responses between nonapneic primary snoring (PS) and obstructive sleep apnea (OSA). Design—Cross sectional with matched samples. Setting—University sleep disorders center. Patients— All PS patients (n=49) available in a series of 428 clinical referrals to a sleep disorders center, and age and gender-matched OSA patients (n=49) selected from the 199 available OSA patients in the series. Interventions—Not applicable. Measurements and Results— Subjects completed the MMPI prior to overnight diagnostic polysomnographic assessment and multiple sleep latency test (MSLT). OSA patients exhibited a mean of 2.3 elevated MMPI scales, which was significantly more than the PS mean of 1.6 elevations, and attributable to higher OSA scores on Depression (D) and Hypochondriasis (Hs). Approximately twice as many OSA patients than PS patients showed disturbed scores on D (49% vs. 25%, p<.05) and Hy (35% vs. 16%, p<.05). On nine of the ten MMPI clinical scales, both patient groups exceeded the elevation rate expected in nondistressed individuals. Among OSA patients, but not PS patients, number of MMPI elevations had a significant negative correlation with sleep efficiency and average blood saturation during NREM, and a significant positive correlation with wake time after sleep onset. Conclusions—Compared to patients with PS, those with OSA have more intense depressive symptoms (e.g., pessimism, inactivity, guilt) and somatic concerns. General psychopathology is associated with blood oxygen saturation only among OSA patients. Nonetheless, PS patients show psychological maladjustment that is qualitatively similar, but quantitatively less severe, than that characterizing OSA.

Aikens, James E.; Caruana-Montaldo, Brendan; Vanable, Peter A.; Tadimeti, Lakshminarayana; Mendelson, Wallace B.

doi: 10.1093/sleep/22.3.362pmid: 10341387

Summary:Study Objective—To evaluate associations between polysomnographic variables in obstructive sleep apnea (OSA) and a variety of psychological responses (including depressive symptoms) as assessed by the Minnesota Multiphasic Personality Inventory (MMPI). Design—Cross-sectional. Setting—University sleep disorders center. Patients—One-hundred seventy eight consecutive clinical OSA patients. Interventions-Not applicable. Measurements and Results-Patients completed the MPI prior to overnight diagnostic polysomnography. Fifty-eight percent demonstrated at least one MMPI elevation (mean=1.8 elevations), with Depression (D) elevated for 32%, Hypochondriasis (Hs) for 30%, and Hysteria (Hy) for 21%. Thirty-eight percent demonstrated two or more elevations, with several variations of Hs-D and Hs-D-Hy configurations evident. “Conversion V” profiles were fairly rare, and a large number of miscellaneous configurations occurred once. Significant correlations were detected between several MMPI scale scores and total sleep time, the apnea-hypopnea index (AHI) during REM, and particularly arterial oxygen saturation, even when partialling out variance related to body mass index (BMI). In contract, D scores were not correlated with any polysomnographic parameters. Based upon MMPI configuration, the sample was subdivided into the following seven profile groups: Nonelevated (n=74); Single D (n=11); Single non-D (n=25); Combined D plus (a) HS or HY (n=7), (b) Hs and Hy (n=10), or (c) other (n=29); and Multiple non-D (n=22). Multivariate analysis controlling for age and gender indicated higher AHI in the Single non-D, Combined D plus other, and Multiple non-D groups, compared to the Single D group. Also, there was lower average oxygen saturation in the Multiple non-D group, compared to Single D, Single non-D, and Nonelevated groups. The Combined D plus HS and/or Hy groups did not differ from each other or from other groups, even when merged. The Multiple non-D findings were unattributable to any specific scale or overall number of elevations. Conclusions—OSA patients who have core depressive symptoms (as measured by MMPI scale D) without significant psychological symptoms in other areas tend to have less severe OSA, whereas those with a diverse set of other psychological symptoms overshadowing depressive symptoms (e.g., somatic focus, emotional reactivity, family/marital problems, cognitive problems, etc.) tend to have greater AHI and lower oxygen saturation. Although it seems probable that these MMPI differences primarily reflect OSA effects, prospective research is needed to confirm this hypothesis.