Nineteen-hour variation of postural sway, alertness and rectal temperature during sleep deprivation.

Nineteen-hour variation of postural sway, alertness and rectal temperature during sleep deprivation were studied. Alertness decreased gradually at night and remained low until morning. Postural sway in the eyes-closed condition increased during early morning. In six of the eight subjects the greatest sway was observed during the 3-h period when rectal temperature was at its minimum. It is suggested that unbearable sleepiness during sleep deprivation will give rise to measurable impairment of postural balance especially during the time zone of temperature nadir.

Temporal order of sleepiness, performance and physiological indices during 19-h sleep deprivation.

Nineteen-hour variation of subjective sleepiness, performance and physiological indices were assessed during sleep deprivation. Longitudinal data of each index had its characteristic curve through which the values changed from day level to night level. A comparison of the time when each curve crossed its mid-range (50% value of its range) showed that those of subjective sleepiness and heart rate were significantly earlier than those of tracking error and coefficient of variation of R-R interval (CV(R-R)), P<0.01. That of rectal temperature was located at between 1:00 and 4:00 am. These temporal relationships were reproducible under two lighting conditions. These results will be useful in considering the occurrence of human errors by night-time workers in the early morning.

[A study on the quantitative evaluation method of human alertness and its application].

This article presents an alertness evaluation method being analyzed by the authors, and discusses its application. With the aim of quantifying the physiological activity of the living body, the alpha-attenuation test (AAT) for evaluation of alertness was assessed. AAT is a method of quantitatively determining alertness level from alpha-wave power spectra during eye closure and opening. 1. The potential for quantification of diurnal change of alertness by the use of the AAT is suggested. Also rated, are a performance evaluation method based on reaction time and target tracking error and a subjective feeling evaluation method using an analog scale on a computer display. Using these methods of evaluation, measurements were made in 9 healthy men and women at 2-hour intervals over the period from 09: 30 to 19: 30. The findings are summarized as follows: 1) Alertness lowered from 13: 30 to 15: 30, as rated by diurnal change determined by the AAT 2) The performance test and subjective feeling scoring revealed decreased target tracing ability and extended reaction time from 13: 30 to 15: 30, accompanied by reduced performance, increased sleepiness, and failure to achieve accurate, quick action. 2. The relation between the quality of rest and the alpha-attenuation coefficient (AAC), the quantitative index of the AAT, was rated. There were some statistical significances between the quality of rest and the AAC. These results suggest that the AAC is found applicable to the quantitative assessment of diurnal changes of physiological activity, and that the AAC is reflected in the quality of rest.