SLEEP

Young, Terry

doi: 10.1093/sleep/19.7.529pmid: 8899930

Enright, Paul L.; Newman, Anne B.; Wahl, Patricia W.; Manolio, Teri A.; Haponik, F. Edward; Boyle, Peter J. R.

doi: 10.1093/sleep/19.7.531pmid: 8899931

Summary:The objectives of this study were to describe the prevalence of snoring, observed apneas, and daytime sleepiness in older men and women, and to describe the relationships of these sleep disturbances to health status and cardiovascular diseases (CVD). A cross-sectional design was employed to study sleep problems, CVD, general health, psychosocial factors, and medication use. The subjects were participants in the Cardiovascular Health Study, which included 5,201 adults, aged 65 and older, who were recruited from a random sample of Medicare enrollees in four U.S. communities. Study measures employed were sleep questions, echocardiography, carotid ultrasound, resting electrocardiogram, cognitive function, cardiopulmonary symptoms and diseases, depression, independent activities of daily living (IADLs), and benzodiazepine use. Thirty-three percent of the men and 19% of the women reported loud snoring, which was less frequent in those over age 75. Snoring was positively associated with younger age, marital status, and alcohol use in men, and obesity, diabetes, and arthritis in women. Snoring was not associated, however, with cardiovascular risk factors or clinical CVD in men or women. Observed apneas were reported much less frequently (13% of men and 4% of women) than snoring, and they were associated with alcohol use, chronic bronchitis, and marital status in men. Observed apneas were associated with depression and diabetes in women. In both men and women, daytime sleepiness was associated with poor health, advanced age, and IADL limitations. The conclusions of the study were that loud snoring, observed apneas, and daytime sleepiness are not associated cross-sectionally with hypertension or prevalent CVD in elderly persons.

Quera-Salva, Maria Antonia; Defrance, Remy; Claustrat, Bruno; De Lattre, Jacques; Guilleminault, Christian

doi: 10.1093/sleep/19.7.539pmid: N/A

Summary:Tolerance to shift work and adaptability to shifting schedules is an issue of growing importance in industrialized society. We studied 40 registered nurses, 20 on fixed day-shifts and 20 on fixed night-shifts, to assess whether workers with rapidly shifting schedules were able to adapt their melatonin secretion and sleep-wake cycles.The day-shift worked 5 days with 2 days off and the night-shift worked 3 nights with 2 off. All night-shift personnel acknowledged shifting back to daytime schedules on their days off. Sleep-wake was determined by sleep logs and actigraphy. To measure 6-sulfatoxymelatonin levels, urine was collected at 2-hour intervals on the last work day and on the last day off.Night-shift workers slept significantly more on days off. Napping on the job occurred in 9/20 night-shift workers (mean 114 minutes) between 3 and 6 a.m. The acrophase of 6-sulfatoxymelatonin in day-shift nurses occurred at similar times on workdays and off days. In night-shift nurses, the acrophase was about 7 a.m. on days off, but had a random distribution on workdays. Further analysis revealed two subgroups of night-shift nurses: six subjects (group A) demonstrated a rapid shift in melatonin secretion (acrophase at near 12 noon on work days and at near 7 a.m. on days off) while 14 nurses (group B) did not shift. Group A nurses slept more in the daytime on work days and their total sleep time was the same as day-shift nurses. Group A was slightly younger and was composed solely of women (there were nine women and five men in group B). Age may be a factor in the ability to adapt to rapidly shifting schedules.

McArthur, Angela J.; Lewy, Alfred J.; Sack, Robert L.

doi: 10.1093/sleep/19.7.544pmid: 8899933

Summary:The case of a 41-year-old sighted man with non-24-hour sleep-wake syndrome is presented. A 7-week baseline assessment confirmed that the patient expressed endogenous melatonin and sleep-wake rhythms with a period of 25.1 hours. We sought to investigate the underlying pathology and to entrain the patient to a normal sleep-wake schedule. No deficiency in melatonin synthesis was found. Furthermore, normal coupling between the melatonin and sleep propensity rhythms was documented using an “ultrashort” sleep-wake protocol. Environmental light exposure was monitored for 41 days, and the circadian timing was calculated. Sensitivity to photic input was determined with light-induced melatonin-suppression tests. Three intensities (500, 1,000, and 2,500 lux) were examined during three separate trials. The 2,500-lux trial resulted in 78% suppression, but the lesser intensity exposures were without substantial effect. Thus, the patient appeared to be subsensitive to bright light. A 4-week trial of daily melatonin administration (0.5 mg at 2100 hours) stabilized the endogenous melatonin and sleep rhythms to a period of 24.1 hours, albeit at a somewhat delayed phase. A 14-month follow-up interview revealed that the patient continued to take melatonin daily, and his sleep-wake schedule was stable to a near 24-hour schedule.

Bergmann, Bernard M.; Gilliland, Marcia A.; Feng, Ping-Fu; Russell, Dawn R.; Shaw, Paul; Wright, Mina; Rechtschaffen, Allan; Alverdy, John C.

doi: 10.1093/sleep/19.7.554pmid: 8899934

Summary:Recent reports have indicated that rats subjected to total sleep deprivation (TSD) by the disk-over-water method and sacrificed when death appeared imminent showed aerobic bacteria in their blood. Yoked control rats did not. Extrapolating from these results, it has been suggested that the late body temperature declines and eventual deaths of TSD rats are caused by septicemia, and that other, earlier-appearing effects of TSD—including weight loss, increased energy expenditure, and regulation of temperature at a higher level—might be mediated by impaired host defenses against bacterial invasion. Three measures of aerobic bacterial invasion were used to evaluate these hypotheses: bacteremia, bacterial colonization in major organs of filtration (liver, kidney, and mesenteric lymph nodes), and adherence of bacteria to the cecal wall. Experiment 1 showed nonsignificant trends toward more bacterial invasion in 4-day TSD rats compared to yoked control rats and no relationship between the bacterial indicators and the early TSD effects. Experiment 2 showed that the elimination of aerobic bacterial infection by antibiotic treatment did not prevent the early TSD effects in 4-day TSD rats. Experiment 3 showed that the elimination of aerobic bacterial invasion in TSD rats did not eliminate the late temperature decline or the progression toward death. The results showed no significant evidence of aerobic bacterial invasion early in TSD and no indication that the major effects of TSD were dependent upon aerobic bacterial invasion.

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

doi: 10.1093/sleep/19.7.563pmid: 8899935

Summary:Nine young adult male (23–30 years old) paid volunteers were subjected to total sleep deprivation (TSD), after two consecutive nights in the laboratory, for 40 hours (from 0800 hours on the first day to 2400 hours on the following day). Oral temperature (OT), reaction time (RT) in a visual vigilance task, and electroencephalogram (EEG; C3, C4, T3, and T4) while performing the task were recorded every 2 hours during TSD and after recovery sleep. One second of EEG, before target and non-target stimuli for every subject and condition was visually inspected, and artifact-free epochs were Fourier transformed. Absolute power (AP) was calculated for 4–20 Hz (full band) and for theta, alpha1, alpha2, and beta1. Analyses of variance (ANOVAs), with TSD and time-of-day as factors, showed the following significant results: TSD induced an increase in RT and AP of the full band at C3 and C4, of all bands at C3, of theta at T3, and of betal at T4 (p < 0.009 for all comparisons). No time-of-day effects nor interactions were found. OT was not affected by TSD. All variables returned to baseline values after recovery sleep. RT and EEG power showed a linear increase with accumulating hours of wakefulness. The increment in RT also correlated with the increase in EEG power. The results demonstrate that the increment in RT is associated with the increase in AP, particularly in the left central cortex; that the EEG may be used to identify sleepiness; and that EEG during task performance is more sensitive to TSD than during relaxed wakefulness.

Gillberg, Mats; Kecklund, Göran; Axelsson, John; Åkerstedt, Torbjörn

doi: 10.1093/sleep/19.7.570pmid: 8899936

Summary:Eight subjects participated on three occasions in a study investigating the effect of a 30-minute daytime nap opportunity on alertness/sleepiness. The baseline condition was a normal home sleep (7.5 hours, with bedtime at 2300 hours). Sleep during the other two conditions was between 2400 hours and 0400 hours. During one of the two 4-hour conditions, a short nap was allowed (between 1045 hours and 1115 hours). Self-ratings of sleepiness/alertness (Karolinska Sleepiness Scale) were recorded every hour. At 10, 12, and 15 hours, the subjects performed a 28-minute visual vigilance task. Electroencephalograms (EEG) and electrooculograms (EOG) were recorded continuously, including during a 10-minute standardized recording procedure at the beginning of each day. Mean total sleep time during the nap was 19.8 (standard error 2.4) minutes. Compared to baseline, EEG/EOG sleepiness and subjective sleepiness were significantly higher and vigilance performance at 10 hours lower, respectively, after the two short sleeps. The nap brought performance to baseline levels, and subjective sleepiness decreased significantly. It was concluded that the short nap had a clear positive effect on alertness.

Roehrs, Timothy; Shore, Ellisa; Papineau, Kate; Rosenthal, Leon; Roth, Thomas

doi: 10.1093/sleep/19.7.576pmid: N/A

Summary:Thirty-four healthy, normal young men and women (21–35 years), with no sleep complaints and a normal screening polysomnogram, some with short (≤6-minute) and some with long (≥l6-minute) average daily sleep latencies on a screening multiple sleep latency test, were studied on two baseline nights (8 hours) and in the “sleepy” group, for 14 consecutive nights of extended (10-hour) or habitual (7.8 ± 0.7-hour) bedtimes. The screening differences between the groups in average daily sleep latency were consistently seen on the two further baseline nights and days. The extension of bedtime in sleepy subjects was followed by an increase in average daily sleep latency relative to randomly chosen sleepy subjects maintained on their habitual sleep schedule for the 14 nights. The increase in average daily sleep latency was associated with a gradual reduction in sleep efficiency over the 14 nights. Some (36%) of the sleepy subjects did not have increased average sleep latencies during the 10-hour bedtime extension. Those showing no increase in average daily sleep latency had an immediate drop in sleep efficiency when the bedtime was increased to 10 hours, suggesting they were unable to sleep longer during the extension. Their short average daily sleep latency was a result of causes other than chronic insufficient sleep.

Briones, Berta; Adams, Nancy; Strauss, Milton; Rosenberg, Carl; Whalen, Christopher; Carskadon, Mary; Roebuck, Theresea; Winters, Mary; Redline, Susan

doi: 10.1093/sleep/19.7.583pmid: 8899938

Summary:One commonly used instrument for evaluating general health and functional status is the medical outcomes survey short form 36 (MOS). Scores obtained from this instrument are known to vary with chronic diseases and depression. However, the degree to which these health dimensions may be influenced by sleep quality or sleepiness is not well understood. A cross-sectional study was performed on the association between general health status, as determined by the MOS, with sleepiness, assessed using a standardized questionnaire [the Epworth sleepiness scale (ESS)] and the multiple sleep latency test (MSLT). One hundred twenty-nine subjects (68 women), aged 25–65 years, without severe chronic medical or psychiatric illnesses, underwent an overnight sleep study, followed by an MSLT (consisting of a series of four attempts at napping at 2-hour intervals), and completed the MOS and the ESS. The mean MSLT score was 11 ± 2 minutes, (range 2–20) and the mean ESS score was 10 ± 5 (range 0–24). Scores for the MOS dimensions “general health perceptions”, “energy/fatigue”, and “role limitations due to emotional problems” were correlated significantly with ESS scores (r = −0.30, −0.41, and −0.30, respectively; p values were all <0.001). The MSLT was also significantly correlated with “energy/fatigue” (r = −0.19; p < 0.05). After considering the effects of chronic illness and/or body mass index in a multiple hierarchical regression analysis, sleepiness, as assessed by the ESS score, explained 8% of the variance in general health perceptions, 17% of the variance in energy/fatigue, 6% of the variance in the summary measure of well-being, and 3% of the variance in the summary measure of functional status. The variation of MOS scores with sleepiness, unrelated to age or chronic disease, suggests that measures of general health status may be broadly influenced by sleepiness and sleep quality. These data suggest that 1) sleepiness has an important impact on general health and functional status, specifically influencing self-perceptions regarding energy/fatigue; 2) a more specific assessment of sleepiness in general health evaluations may help explain some of the observed variability in these measures across subjects; and 3) general health measures may be useful in the evaluations of patients with sleep disorders.

Chediak, Alejandro D.; Acevedo-Crespo, Juan C.; Seiden, David J.; Kim, Helen H.; Kiel, Michael H.

doi: 10.1093/sleep/19.7.589pmid: 8899939

Summary:We retrospectively analyzed night-to-night variability in the indices of sleep apnea in a group of men who underwent consecutive polysomnograms (PSGs) in the evaluation of impotence. The study group consisted of 37 subjects. Fifty-seven percent of the subjects had an apnea/hypopnea index (ART) of 5 or more on the first PSG, whereas 70% met this criterion on the second study. On both PSGs, 49% of the subjects exhibited an AHI of 10 or more. The AHI varied by 10 or more between the two PSGs in 32% of the cases. Using a threshold AHI of 5 or more to establish a diagnosis of sleep apnea, 22% of the subjects would not have been diagnosed by the first PSG, and the false negative rate for the first PSG was 50%. The variability observed in the AHI could not be explained by differences in total sleep time, sleep stages [1 through 4 and rapid eye movement (REM) sleep]; the amount of time sleeping supine, or a combination of sleep stage and position. The mean AHI, the apnea/hypopnea-related nadir, and the mean oxyhemoglobin saturation did not differ among the two PSGs. Our observations support the notion that for groups of subjects the mean AHI is relatively constant across 2 nights of study in the sleep laboratory. However, when an AHI of 5 or 10 or more is the sole criterion used to establish the diagnosis of sleep apnea, a single PSG may not be sufficient to rule out the presence of a sleep apnea syndrome.