PSD-Partial Sleep Deprivation
The effects of a shortened duration of sleep on the human performance has been examined in several studies in the Arbeitsmedizinischen Simulationsanlage (medical simulation fadility)AMSAN The examinations are based on the hypothesis that partial sleep deprivation leads acutely and cumulatively to a reduction of the mental performance. The influence of hypnoxia (oxygen deficiency) and alcohol will serve as reference stressors in order to achieve a standardization of the performance tests used in the examination to known influences decreasing performance.
The studies were conducted under the designation PSD = Partial Sleep Deprivation.
The decrease in sleep duration due to situational factors is a typical stressor appearing in questions concerning aviation as well earth-bound traffic. It was determined in seperate examinations of stress and strain on helicopter pilots in the air rescue service that pilots slept significantly less during the work hours than they did in their free time. Examinations on pilots on duty during long-distance flights also showed a decreased duration of sleep caused by jet-lag and by unfavorable lay-over times. Several objective and subjective measurement procedures are applied in the assessment of the strain and possible decrease in performance, the sensitivity and reproductability of which have to be adapted to the respective problem areal.
The following tests were conducted::
- duration and quality of sleep
- sleep-wake rhythm
- circadian rhythm
- dim light melatonin onset
- stress and recreation
- performance with specific tasks from theAGARD-STRES-Battery and with further computer-supported performance tests
- Subjective work strain and fatigue.
The mental performance can be understood as an interaction of different elementary components:
- comparison by memory
- deduction of similarity
- induction etc.
Concluding, it remains to be emphasized:
The AGARD-STRES-Battery ffers decisive advantages like: individual composition of standard tasks, execution on "small" computers and versatile database due to wide spreading and, consequently, sufficient validation;
Alcohol (approx. 0.1 % in the breath), oxygen deficiency (only 10 % O2 in exhalation gas) and sleep deprivation (on the 3rd night with only 5 hours of sleep every night) cause evenly directed and evenly strong decreases in performance.
In the lower illustration, the three stressors oxygen deficiency, alcohol and sleep deprivation are compared and examined in respect to their influence on motorial performance using the "unstable tracking task".
We can see clearly that
- less oxygen
- more alcohol
- less sleep
result in a deterioration of the test result. It is important that the deterioration of attention/motorial performance by a shortened duration of sleep is as high as the deterioration caused by a respiratory alcohol percentage of 0.07 %.