SLEEP

Mosko, Sarah; Richard, Christopher; McKenna, James; Drummond, Sean

doi: 10.1093/sleep/19.9.677pmid: 9122552

SummaryArousal is an important protective response during sleep, and arousal deficit is hypothesized to play a role in the etiology of sudden infant death syndrome (SIDS). Because environmental or caretaking factors have been shown to exert powerful effects on susceptibility to SIDS, manipulations that facilitate arousability might be protective against SIDS. All-night laboratory polysomnographic recordings were performed in 20 routinely bed-sharing and 15 routinely solitary sleeping healthy breast-feeding Latino infants within the peak age range for SIDS, in both bedsharing (with mother) and solitary sleeping environments. The most important findings revealed by repeated measures analyses of variance were a significant reduction in stage 3/4 sleep and an inverse increase in stage 1/2 sleep on the bedsharing night compared to the solitary night, irrespective of routine sleeping arrangement. Shorter mean duration episodes of stage 3/4 sleep and longer mean stage 1/2 sleep episodes accounted for these differences. Because the arousal threshold is high in the electroencephalographic delta range, by limiting the amount of stage 3/4 sleep, bedsharing should promote infant arousability and might be protective against SIDS. The results also suggest that accepted normative values for infant sleep established in solitary sleeping infants may not be representative of infants raised in social sleeping environments.

Richard, Christopher; Mosko, Sarah; McKenna, James; Drummond, Sean

doi: 10.1093/sleep/19.9.685pmid: 9122553

SummaryThe impact of mother-infant bedsharing on infant sleeping position, orientation, and proximity to the mother was assessed in 12 breast-feeding Latino mother-infant pairs. Six routinely bedsharing and six routinely solitary-sleeping pairs slept 3 nights in the sleep laboratory. The first night matched the routine home condition, followed by 1 bedsharing night and 1 solitary-sleeping night in random order. During bedsharing infants were never placed prone, regardless of their routine sleeping condition. On the bedsharing night, mothers and infants spent most of the night oriented toward each other; seven of 12 infants remained oriented toward their mothers the entire night. While sleeping in a face-to-face orientation, most pairs slept most of the time less than 30 cm apart with appreciable amounts of time at less than 20 cm. This orientation and proximity should facilitate sensory exchanges between mother and infant which, we hypothesize, influence the infant's sleep physiology and nocturnal behavior. We conclude that bedsharing minimizes the use of the prone infant sleeping position, probably in part to facilitate breast feeding. By promoting nonprone positions, bedsharing may protect some infants from sudden infant death syndrome (SIDS), since prone sleeping is a known risk factor for SIDS. The large percentage of the night that mothers spent oriented toward their infants suggests that a higher degree of maternal vigilance may also result from bedsharing.

Saletu, Bernd; Klösch, Gerhard; Gruber, Georg; Anderer, Peter; Udomratn, Pichet; Frey, Richard

doi: 10.1093/sleep/19.9.691pmid: N/A

SummaryFirst-night effects (FNE) were comparatively investigated in patients with disorders in initiating and maintaining sleep (DIMS) associated with generalized anxiety disorder (GAD) in laboratory (n = 22) and home sleep polysomnography (n = 21). Patients had to be drug-free for at least 2 weeks prior to the first recording. Evaluation measures included 1) objective data on sleep initiation and maintenance; 2) sleep architecture based on polysomnographic recordings, analyzed visually according to the criteria of Rechtschaffen and Kales; 3) subjectively estimated sleep and awakening quality, assessed by a self-rating scale and visual analogue scales; 4) objective awakening quality as measured by a psychometric test battery; and 5) psychophysiological data, including critical flicker frequency, muscle strength, pulse, and blood pressure. Statistical analysis using multivariate analysis of variance (MANOVA) demonstrated multiple FNE in both groups regarding sleep efficiency, total sleep time, percentage of time in stage 2 sleep, percentage of time in stage 3/4 sleep, minutes of rapid eye movement (REM) sleep, and REM sleep latency. There was a group-by-night effect in the number of awakenings. There were no significant FNE regarding subjective sleep and awakening quality in either group. Differential adaptation effects were observed in attention and fine motor activity, with improvement in laboratory-recorded patients and deterioration in home-recorded patients. Differential findings also occurred in regard to evening blood pressure, with laboratory-recorded patients showing more adaptation.

Mendelson, Wallace B.

doi: 10.1093/sleep/19.9.698pmid: N/A

SummaryThe relationship between reports of falling down and the administration of sedative/hypnotics or other psychotropic drugs was examined during a 1-year period in a 1,000-bed teaching hospital. It was found that patients who fell were approximately 2.7 times as likely to have received a psychotropic drug compared to control subjects matched for age, gender, and medical service. Orally administered benzodiazepines that were significantly associated with falls included temazepam, alprazolam, diazepam, and lorazepam, but not triazolam, chlordiazepoxide, or chlor-azepate. When viewed as the frequency of falls per dose dispensed by the pharmacy, the highest rates were with lorazepam (0.0012 falls/dose) and alprazolam (0.0010 falls/dose), whereas the lowest rate was for diazepam (0.00052 falls/dose). Falls with antidepressants were comparable to the higher rates with benzodiazepines; frequencies for nortriptyline and sertraline were 0.0021 and 0.0012 falls/dose, respectively. Patients receiving two or three psychotropic drugs concomitantly were 3.7 and 9.5 times, respectively, more likely to fall compared to control subjects. Patients under 21 years old who fell were also significantly more likely to have received a psychotropic medication compared to control subjects. Although these data are associational and do not necessarily imply causality, prudence indicates that the risk of falls be considered in making benefit/risk decisions about prescribing sedative/hypnotics.

Mendelson, Wallace B.; Thompson, Charles; Franko, Thomas

doi: 10.1093/sleep/19.9.702pmid: 9122556

SummaryReported adverse reactions to orally administered sedative/hypnotics were systematically recorded during a 3-year period in a 1,000-bed teaching hospital. Reported cases were reviewed by a multidisciplinary committee and then by a pharmacist, and judgments were made as to type, severity, and outcome of adverse reactions. Probability that the reaction was caused by the medication was recorded in terms of both a global judgment and a systematic scale. The frequency of adverse reactions was calculated as a percentage of total doses of each agent dispensed by the pharmacy during the same time period.The assessment of benzodiazepine sedative/hypnotics indicated that adverse reactions were rare, ranging from frequencies of 0.05% of doses administered (lorazepam) to none (chlorazepate). The median frequency of reported adverse reactions was 0.01%, or 1 in 10,000 doses. The vast majority of reactions could be viewed as extensions of the therapeutic effect, were considered mild, and were without sequelae. All adverse reactions occurred in patients over 55 years old except for four patients under age 50 who received lorazepam. There were no reported cases of violent behavior or global amnesia.

Aaron, Joshua N.; Carlisle, Carol C.; Carskadon, Mary A.; Meyer, Thomas J.; Hill, Nicholas S.; Millman, Richard P.

doi: 10.1093/sleep/19.9.707pmid: 9122557

SummaryOur laboratory previously reported continuously monitored peak sound levels in several areas at Rhode Island Hospital. The number of sound peaks greater than 80 A-weighted decibels (dBA) was found to be high in the intensive and intermediate respiratory care unit (IRCU) areas, even at night. Environmental noise of this magnitude is potentially sleep-disruptive. Therefore, we hypothesized that nocturnal peak sound levels of ≥80 dBA would be associated with an increase in EEG arousals from sleep in patients in the IRCU. Six patients underwent sleep monitoring while environmental peak sound levels were continuously recorded. Each 8-hour period (2200 to 0600 hours) was broken down into 30-minute segments. If there were 10 minutes or more of wakefulness in a segment, that segment was dropped from further analysis. Of the remaining 61 segments, there was a very strong correlation (r = 0.57, p = 0.0001) between the number of sound peaks of ≥80 dBA and arousals from sleep. These 61 periods were then classified as quiet, moderately loud, and very loud based on the number of sound peaks (≤5, 6–15, and >15, respectively). Analysis of variance revealed a significant difference between the number of arousals (p = 0.001) in quiet periods and that in very loud periods. We conclude that environmental noise may be an important cause of sleep disruption in the IRCU.

George, C. F. P.; Boudreau, A. C.; Smiley, A.

doi: 10.1093/sleep/19.9.711pmid: 9122558

SummaryMany patients with obstructive sleep apnea (OSA) or narcolepsy have difficulty driving and increased automobile accidents. Previously we have shown that OSA patients perform poorly on a laboratory-based divided-attention driving test (DADT). Patients with narcolepsy may be as sleepy as OSA patients, so we compared performance on the DADT of OSA patients with that of narcolepsy patients. Twenty-one male OSA patients [age 49.3 ± 12.7 (SD) years; apnea-hypopnea index (AHI) 73 ± 29] 21 age- and sex-matched controls, and 16 narcoleptics (12 males, four females; age 39.6 ± 15.2 years) underwent polysomnography followed by daytime sleep latency testing (MSLT). Following a practice session, all subjects were given the DADT for 20 minute prior to each daytime nap of the MSLT. Narcolepsy patients were younger than OSA or controls and more sleepy than OSA patients. Tracking error was much worse in patients than controls (228 ± 145 cm for OSA vs. 196 ± 146 for narcolepsy vs. 71 ± 31 for controls; p < 0.001), although half of either patient group performed as well as controls. There was only a weak relationship between MSLT and tracking in either patient group. We conclude that impairment in laboratory driving performance skills is seen in both groups of sleepy patients but the degree of impairment is difficult to predict from sleepiness alone.

Richardson, Gary S.; Wyatt, James K.; Sullivan, Jason P.; Orav, E. John; Ward, Allan E.; Wolf, Marshall A.; Czeisler, Charles A.

doi: 10.1093/sleep/19.9.718pmid: N/A

SummaryWe studied 26 physicians in postgraduate medical training (“house staff”) to objectively quantify their sleep, alertness, and psychomotor performance while working on call. This study provided precise data on the extent of sleep deprivation during a typical call night, the workload factors predictive of sleep loss, and the extent to which protected time for sleep within the call night can ameliorate sleep loss and consequent daytime sleepiness. We used ambulatory EEG recording equipment and a standardized computer-based performance test to monitor sleep and alertness over the course of a 36-hour call day. Comparisons were made between interns provided with 4 hours of protected time for sleep by a covering resident (“night-float”) and interns without such coverage. As anticipated, we found evidence that hospital interns were severely sleep-deprived, to an extent even greater than prior behavioral observations have suggested. Interns in both conditions spent an average of less than 5 hours (295.4 minutes) in bed attempting to sleep and obtained an average of 3.67 hours (220.1 minutes) of sleep (range 37.4–358.4 minutes). Provision of the night-float for 4 hours did not significantly change total sleep time (TST) (212.8 minutes covered vs. 224.9 minutes uncovered), but sleep efficiency was significantly improved (86.5% vs. 70.3%; p = 0.001). Covered interns also obtained significantly more slow-wave sleep than the uncovered interns (65.4 minutes vs. 51.1 minutes; p = 0.05). However, measures of alertness and performance were not significantly different between the two groups and were only weakly related to TST. These data suggest that significant chronic sleep deprivation is relatively unaffected by sleep obtained in the hospital and that provision of protected time for sleep does not significantly improve TST.

Bishop, Christopher; Rosenthal, Leon; Helmus, Todd; Roehrs, Timothy; Roth, Thomas

doi: 10.1093/sleep/19.9.727pmid: 9122560

SummaryThe multiple sleep latency test (MSLT) is a valuable tool in the assessment of excessive daytime sleepiness (EDS). Additionally, multiple sleep onset rapid eye movement periods (SOREMPs) are a frequent occurrence in patients with narcolepsy. To date, however, few studies have evaluated the frequency of SOREMPs in a population of healthy control subjects. Subjects participating in a variety of sleep studies were screened with a nocturnal clinical polysomnogram, followed by the MSLT. Subjects were required to be drug free and have no sleep-related symptoms or medical or psychiatric conditions. Of the 139 subjects who were screened, 24 (17%) had two or more SOREMPs. These individuals were more likely to be male, younger, and sleepier than those-with one or zero SOREMPs. The etiology of two or more SOREMPs in healthy controls was not apparent from the clinical or polysomnographic evaluation. Although it is possible that these findings are early signs of narcolepsy, subjects reported being free of any sleep-related complaints. Further investigations into the determinants of multiple SOREMPs and their reliability among asymptomatic populations are warranted.

Tanaka, Hideki; Hayashi, Mitsuo; Hori, Tadao

doi: 10.1093/sleep/19.9.731pmid: 9122561

SummaryThe purpose of this study was to examine the durations of individual occurrences of each of nine hypnagogic electroencephalographic (EEG) stages and the interchange relationship among these stages. Most of the alpha patterns (stages 1, 2, and 3), ripples (stage 5), and spindles (stage 9) tended to last >2 minutes. On the other hand, histograms of the durations of time in EEG flattening (stage 4) and vertex sharp wave (stages 6, 7, and 8) patterns had peaks that lasted <30 seconds. Analysis of the sequences of EEG stage changes demonstrated that shifts to adjacent stages were most common for all stages. A smooth change in EEG stage occurred in the downward or upward direction in the hypnagogic state. This was especially true for the first five stages. EEG stages with vertex sharp waves (stages 6, 7, and 8), however, showed less-smooth changes, with approximately 20% of all changes involving a jump of more than one stage. These results show that the basic EEG activities in the sleep onset period are the alpha, theta, and sleep spindles activities, whereas the activities of vertex sharp waves seem to have a secondary or enhancing role, instead of independent characteristics.