Engineering topics

Webb, W. B.

Publications and source records attributed to Webb, W. B..

6 records

NASA NTRS1975

Time estimates in a long-term time-free environment

Subjects in a time-free environment for 14 days estimated the hour and day several times a day. Half of the subjects were under a heavy exercise regime. During the waking hours, the no-exercise group showed no difference between estimated and real time, whereas the exercise group showed significantly shorter estimated than real time. Neither group showed a difference after the sleeping periods. However, the mean accumulated error for the two groups was 48.73 hours and was strongly related to the displacements of sleep/waking behavior. It is concluded that behavioral cues are the primary determinants of time estimates in time-free environments.

Lavie, P.↗

NASA NTRS1975

Electroencephalographic studies of sleep

Various experimental studies on sleep are described. The following areas are discussed: (1) effect of altered day length on sleep, (2) effect of a partial loss of sleep on subsequent nocturnal sleep; (3) effect of rigid control over sleep-wake-up times; (4) sleep and wakefulness in a time-free environment; (5) distribution of spindles during a full night of sleep; and (6) effect on sleep and performance of swiftly changing shifts of work.

Webb, W. B.↗

NASA NTRS1974

Regularity in the control of the free-running sleep-wakefulness rhythm

In the present experiment, rigid control over the sleep and wake-up times was employed in an attempt to contain the natural rhythm to a 24-hr cycle. Eight subjects were isolated from all time and social cues for 10 days. They were placed on a rigid schedule of sleep between 11 p.m. and 7 a.m. The results indicate that, for practical purposes, the free-running sleep-wakefulness rhythm can be contained to a 24-hr cycle by rigid control of the sleep portion of the cycle. When part of the control was released by allowing the subjects to sleep beyond 7 a.m., they slept an average of 67 min longer and showed sleep latencies which averaged 73 min. From these data it is concluded that control of the sleep portion of the sleep-wakefulness cycle, particularly control of the wake-up time, is sufficient to contain the free-running sleep-wakefulness rhythm to a 24-hr cycle.

Webb, W. B.↗

NASA NTRS1974

Sleep and waking in a time-free environment

The sleep and waking of 14 subjects in time-free environments were studied for 14 days. Half of the subjects had a heavy exercise regime. All subjects exhibited a longer-than-24-hr rhythm, but the groups did not differ from each other in this extension of the rhythm. There were large individual differences between subjects and large variations from the projected sleep and waking times. The overall amount of sleep increased in the environment, and there were marked increases in both shorter and longer sleep and waking period lengths. Exercise did not increase the overall amount of sleep but did increase the variability in the distribution of sleep. The overall distribution of sleep stages during sleep did not differ from baseline measures or between groups.

Webb, W. B.↗

NASA NTRS1972

Estimation of the passing of four consecutive hours.

In the AM and PM (9 to 1) males and females gave estimates of the hourly passing of time for 4 hr. There were no differences between sexes or AM/PM estimates. The group was less than 1 min off after an hour and 12 min off after 4 hr. There was a wide range of individual differences. One-fourth of the subjects were within an error of 10 min after 4 hr whereas another one-fourth were off more than 50 min. The accuracy of estimates was about equal to accuracy of awakening from sleep to randomly chosen awakening times.

Webb, W. B.↗

NASA NTRS1972

Patterns of sleep behaviour.

Discussion of the electroencephalogram as the critical measurement procedure for sleep research, and survey of major findings that have emerged in the last decade on the presence of sleep within the twenty-four-hour cycle. Specifically, intrasleep processes, frequency of stage changes, sequence of stage events, sleep stage amounts, temporal patterns of sleep, and stability of intrasleep pattern in both man and lower animals are reviewed, along with some circadian aspects of sleep, temporal factors, and number of sleep episodes. It is felt that it is particularly critical to take the presence of sleep into account whenever performance is considered. When it is recognized that responsive performance is extremely limited during sleep, it is easy to visualize the extent to which performance is controlled by sleep itself.

Webb, W. B.↗