Biomedical subjects

R Downey

Publications and source records attributed to R Downey.

5 recordsLinked to original sources

PubMed1992

Training subjective insomniacs to accurately perceive sleep onset.

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.

Adolescent↗

PubMed1992

Operation Everest II: arterial oxygen saturation and sleep at extreme simulated altitude.

Frequent sleep disturbances and desaturation during sleep are common at high altitude, but few data are available from the highest altitudes at which humans are known to sleep. Because sleep fragmentation at low altitude may impair mental function and oxygen deprivation produces lasting central nervous system abnormalities, a better understanding of the severity of sleep disturbances and oxygen desaturation at extreme altitudes is important. The purpose of this study was to determine the severity of sleep disturbance and the extent of arterial oxygen desaturation at extreme simulated altitude. Out of eight healthy male subject volunteers who started, five aged 27.2 +/- 1.5 yr completed the study during 6 weeks of progressive hypobaric hypoxia in a decompression chamber. The men were studied at barometric pressures of 760, 429, 347, 282 mm Hg and following return to 760 mm Hg. All demonstrated frequent nighttime awakenings (37.2 awakenings per subject per night at 282 mm Hg, decreasing significantly to 14.8 on return to sea level, p less than 0.05). Total sleep time decreased from 337 +/- 30 min at 760 mm Hg to 167 +/- 44 min at 282 mm Hg (p less than 0.01). Rapid eye movement (REM) sleep decreased from 17.9% +/- 6.0% of sleep time at sea level to 4.0% +/- 3.3% at 282 mm Hg (p less than 0.01). Sleep continuity as reflected by brief arousals increased from 22 +/- 6 arousals per hour of sleep at sea level to 161 +/- 66 arousals per hour at 282 mm Hg (p less than 0.01). All subjects showed arterial oxygen desaturation proportional to the altitude. The average oxygen saturation (SaO2) was 79% +/- 3% at 429 mm Hg, 66% +/- 6% at 347 mm Hg, and 52% +/- 2% at 282 mm Hg. Sleep stage had only a minimal effect on SaO2 at any altitude. SaO2 was negatively correlated with brief sleep arousals, r = -0.72, p less than 0.01. All subjects demonstrated periodic breathing with apneas throughout much of the night at 347 and 282 mm Hg. These data indicate that sleep quality progressively worsens as SaO2 decreases despite lack of progressive changes in sleep stages at altitude. This study extends previous information on the severity of desaturation during sleep, and suggests that improvements in oxygenation might prove beneficial in restoring consolidated sleep, possibly even improving daytime performance.

Adult↗

PubMed1989

Managerial functions of college and university foodservice managers.

This study examined managerial roles in college and university foodservice at three organizational levels. The study population included foodservice managers at National Association of College and University Food Services (NACUFS) member schools with a minimum annual budget of +3 million. The 999 managers from 80 colleges and universities who participated were categorized into three groups: assistant, associate, or director of foodservice; unit manager; and manager reporting to unit manager. They rated 51 activity statements on importance and time demand. Maintaining standards of quality was rated most important and most time demanding by all three groups of managers. Perceived importance and time demand of activities increased as managerial level increased. Activity statements were categorized into Mintzberg's 10 managerial roles. Significant differences in importance and time demand ratings among the three managerial groups were indicated for all 10 roles. However, perceived importance and time demand of roles increased as managerial level increased with two exceptions. Disturbance handler and leader roles were rated more time consuming by lower level managers.

Adult↗

PubMed1987

Performance during frequent sleep disruption.

Performance on a simple addition task was measured during three schedules of frequent sleep disruption for 2 nights. Five young adults had their sleep briefly disturbed for 2 nights in 3 separate weeks either every 1 min, every 10 min, or at sleep onset after an undisrupted 2.5-h sleep period. Subjects were required to perform a two-number, two-digit addition problem as rapidly as possible on awakening. Main effects were found for sleep disruption condition and time of night, and a significant interaction between the two was also observed. Latency to response was longest for the 10-min condition on night 1, on night 2, however, response latencies were longest in the 1-min condition. Response latencies were fastest in the 2.5-h condition for both nights of disruption. Arousal thresholds were also gathered across both nights. Arousal thresholds were consistently the highest in the 1- and 10-min conditions for both nights of disruption, reaching maximum threshold levels at the end of night 1. Arousal threshold was significantly positively correlated with response latency. Sleep stages (slow-wave sleep (SWS), SWS + REM (SWSR), and total sleep time minus stage 1 sleep) were poor predictors of performance changes across the 2 disruption nights. The data were best explained by sleep continuity theory, which posits that a period of at least 10 min of uninterrupted sleep is required for restoration to take place.

Adolescent↗

PubMedDate not supplied

Cutting the cake.

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Community Health Services↗