Conditions Of Sleep Loss Research Articles

On adaptive control, sleep loss, and fatigue

AbstractThis paper considers the relationship between levels of control and stressors put forward by Broadbent in Decision and Stress. Broadbent speculated that a lower level of control could be maintained in an optimal state by the activity of an upper level such that performance outcomes remained constant. The upper level, however, could become fatigued, allowing any inefficiency of the lower to be reflected in performance. He thought that lower inefficiency was a function of sleep deprivation, among other stressors. To illustrate the ideas put forward by Broadbent, preliminary results from an extended study of the effects of varying amounts of sleep deprivation and length of work day on an adaptive control task are presented, with the aim of exploring the value and limitation of the levels approach. The adaptive control task used is one developed by Broadbent to explore levels of control. The paper considers how levels of control could relate to behavioural outcomes of 'performance level' and 'work rate' under conditions of sleep loss and fatigue, and discusses some of the advantages and disadvantages of so doing. We conclude that the levels of control approach offers a potentially rich interpretive framework for the effects of stressors on performance, but that attempting to relate particular performance indices to particular levels is a less fruitful diagnostic endeavour.

Perceived exertion under conditions of sustained work and sleep loss

Abstract The rated perceived exertion (RPE) for treadmill walking carrying a 22 kg pack was measured in two studies with heart rate, workload and psychological measures. Study 1 used an initial treadmill speed and grade producing 40% of maximal oxygen consumption. Exercise subjects walked 1/2-h, then did other tasks for 20-h for 16 sessions on two 20 h long days. Group I had a 4 h nap, while Group 2 had 4 h of rest between workdays. Subjects maintained the 40% workload throughout the two days with a 3 h nap between days, one group starting exercise at midnight and one at noon. A steady increase in RPE over the sessions each day was found in each study. There were no differences in RPE between the Nap and Rest groups in Study 1 or between the midnight and noon groups in Study 2. RPE was higher on Day 2 in each study. RPE correlated significantly with heart rate, distance walked or elevation at most time periods on the first workday in Study 1, but not Study 2. RPE was positively correlated with fatigue, sy...

Sleep and performance in young adults and older normals and insomniacs during acute sleep loss and recovery

Many changes occur in sleep as a function of aging, but it is not known whether these changes result in sleep being less restorative. To examine the sleep restorative process, groups of 12 normal young adults and 12 normal and 12 insomniac male subjects, age 55–71, were totally sleep deprived for 64 hours and then allowed recovery sleep. Response speed, immediate recall, sleepiness, and body temperature were tested at approximately 2300, 0115, 0330, 0530 and 0800 during baseline, sleep loss, and recovery nights. Significant group (age or insomnia) by sleep loss condition interactions were found for reaction time and immediate recall performance measures. Similar significant interactions were found for oral temperature and all EEG sleep variables except total time in bed, percent stage 1, and percent REM. It was concluded that performance recovery following sleep loss was no slower in older subjects than in younger subjects despite very different recovery sleep stage parameters. This implied that aging effects on sleep are developmental rather than degenerative.

Performance and sleepiness as a function of frequency and placement of sleep disruption.

ABSTRACTEight normal young adult sleepers spent 4 nonconsecutive weeks in the laboratory. Each week consisted of a baseline night followed by 2 consecutive nights of disrupted sleep, followed by 2 recovery nights. Disruption conditions included: a) brief awakening after each minute of accumulated sleep, b) brief awakening after each 10 min of accumulated sleep, c) 2.5 hrs of normal sleep followed by a brief awakening at each sleep onset, and d) total sleep deprivation. Morning testing revealed that all disruption conditions decreased sleep latency in a morning nap test. Performance after 1‐min disruptions approximated that seen after total sleep loss. Performance decrements were less in the 10‐min condition and least in the 2.5‐hr sleep condition. Performance under baseline and total sleep loss conditions was used to predict performance during the sleep deprivation condition using four sleep stage rules. Total time asleep and total time asleep minus stage 1 predicted performance poorly. Total SWS plus REM predicted performance best but could not differentiate the 10‐min and 2.5‐hr conditions. Therefore, it was concluded that the data were most parsimoniously explained by the Sleep Continuity Theory—i.e., that periods of uninterrupted sleep in excess of 10 min are required for sleep to be restorative.

Decrements in logical reasoning performance under conditions of sleep loss and physical exercise: the factor of sentence complexity.

Baddeley's Logical Reasoning Test was used in a series of Sustained Operations (SUSOP) studies involving 100 US Marine Corps enlisted subjects, to assess the effects of sleep loss and long-term physical exercise on the ability to process complex information. The percent correct answers to the eight Logical Reasoning sentence types involving different voice (active vs passive), use of negatives, and outcome (true vs false) were analyzed over three days across three levels of exercise and rest conditions in the seven studies. A multivariate analysis of variance indicated no differences on the baseline day among the seven studies. Analyses on the baseline day and throughout the next two continuous workdays (CWs) showed consistently higher percent correct for the actively worded than for the passively worded sentences. The sleep loss over the two CWs resulted in a significant decrease in percent correct for the statements which had active wording. Sleep loss had no effect on statements with passive wording. There were no differences in comprehension between groups which had different rest conditions (no rest, 3- or 4-hr. nap, 8-hr. sleep) between the two CWs for any of the sentences; and there was no recovery from prerest to postrest. Fatigue due to exercise during either CW had no effect on comprehension for any of the sentence types. The sleep loss effects on comprehension seem due to a lessening of the attention given to those more simple sentences in active voice, whereas increased arousal may have been elicited by the more complex sentences in passive voice. The increased attention to the passive statements may have overcome the effects of sleep loss. The present study shows the usefulness of analyzing responses to the logical reasoning test by sentence complexity for indicating selective cognitive changes in the processing of information.

The perception of performance in stress: the utilisation of cognitive facts by nondepressed and depressed students.

Three experiments are reported in which expectancies about performance in stressful conditions by nondepressed and depressed nonclinical populations were examined. The first experiment was concerned with estimates of either errors or response rates made in advance, with regard to the likely competence level of a (hypothetical) person allegedly working in conditions of either loud noise, fatigue, sleep loss, social stress, or incentive. Nondepressed subjects as well as depressed subjects provided negative expectancies. The second experiment involved obtaining an estimate of personal competence in conditions where subjects were instructed that personal performance on the task would be required after the estimate had been provided. Nondepressed subjects differed from depressed subjects in that the estimates of the former were less negative in terms of the magnitude of the estimates provided. A third experiment was designed to see whether the negative expectancies about performance in stress exhibited both by nondepressed and by depressed subjects would be used in making allowances for the competence of a typist on the basis of a typescript allegedly produced under high noise conditions. An unexpected effect was that depressed subjects judged the typist more harshly and failed to make allowance for adverse working conditions in the way that nondepressed subjects did. The results are discussed in terms of the implications for understanding cognitive factors in depression.