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Biomedical subjects

S Folkard

Publications and source records attributed to S Folkard.

At least 91 records · Page 5Linked to original sources
PubMed1976

Comparative study of short-term recovery of mental efficiency after anaesthesia.

Two common general anaesthetic techniques were compared to evaluate the time taken for the patient's mental efficiency to recover sufficiently for him to be escorted home after inguinal herniorrhaphy. Recovery in performance efficiency to at least 60% of the patient's own maximum is suggested as a criterion for discharge, and this needs a stay in hospital of seven to nine hours.

Anesthesia, General↗
PubMed1975

Diurnal variation in logical reasoning.

Subjects performed two tests of logical reasoning at each of six different times of day. In terms of speed, preformance on both tests was found to improve markedly from 08.00 to 14.00 and then to fall off fairly rapidly. Accuracy was found to decrease fairly linearly over the day. The results are interpreted as indicating that the different functions relating performance efficiency to time of day found by previous workers are due to differences in task demands rather than to individual differences. It is suggested that the larger the short-term memory component of a task the earlier in the day performance peaks.

Achievement↗
PubMedDate not supplied

Multi-oscillatory control of circadian rhythms in human performance.

Circadian rhythms are known to exist in many measures of human performance efficiency as well as in physiological processes. The demands of a task, and in particular its 'working memory' load, play a large part in determining the time of day at which it is best performed. Furthermore, task demands may affect the speed with which performance rhythms adjust to the altered sleep/wake schedules occasioned by shift-work and rapid time-zone transitions. These differences in rate of adjustment may be explained by a similar multi-oscillatory model to those proposed for physiological rhythms. These assume any given circadian rhythm to be jointly controlled by two endogenous oscillators. The first is thought to be relatively immune to exogenous factors and to control the temperature rhythm, while the second is thought to be more influenced by exogenous factors and to have the major role in governing the sleep/wake cycle. Normally, the pronounced 24-h time cues, or 'zeitgebers', in our environment result in both oscillators, and hence all circadian rhythms, running with a period of 24 h. However, under altered sleep/wake schedules, and in conditions of temporal isolation, the temperature rhythm and sleep/wake cycle may separate from one another and run with distinctly different periods. When such 'internal desynchronization' occurs, other physiological rhythms have been found to run in synchrony with one or other of these two functions. This finding forms the basis of current multi-oscillatory models. However, studies of abnormal sleep/wake schedules suggest that the rhythm in working memory performance may sometimes separate from both the sleep/wake cycle and temperature rhythm by running with a period of less than 24 h. We have investigated this possibility here and our results indicate control of working memory performance rhythms by a previously unidentified oscillator with an autonomous period of about 21 h.

Adult↗
PubMedDate not supplied

Independence of the circadian rhythm in alertness from the sleep/wake cycle.

It is common knowledge that our feelings of alertness or drowsiness vary throughout the day. Indeed, this diurnal variation is so widely accepted that it has been used to validate the drowsy/alert component of activation obtained from mood adjective checklists. There is, however, some evidence from sleep deprivation and shiftwork studies that this variation is not simply a reflection of our sleep/wake cycle, as might be expected, but is at least partially dependent on an endogenous circadian (approximately 24 h) oscillator such as that proposed to account for the circadian rhythm in body temperature and other physiological variables. Here we have tested this suggestion by separating the body-temperature rhythm from the sleep/wake cycle by progressively shortening artificial time cues (zeitgebers). Our results indicate that the circadian rhythm in alertness can become independent of both the sleep/wake cycle and the rhythm in body temperature. Further, and contrary to our expectations, the results suggest that the sleep/wake cycle exerts less influence on the alertness rhythm than it does on that of temperature.

Adolescent↗