VALIDATION OF THE S-COMPONENT AND C-COMPONENT OF THE 3-PROCESS MODEL OF ALERTNESS REGULATION

This paper summarizes work to validate and develop further the homeost atic and circadian component of a quantitative (computerized) three-pr ocess model for predicting alertness/sleepiness in daily living. The m odel uses sleep data as input and contains circadian and homeostatic c omponents (amount of prior wake and amount of prior sleep), which are summed to yield predicted alertness on a scale between 1 and 16. The p resent validation was carried out using regression analysis, with slee piness-related electroencephalographic parameters (alpha power density ) from held and laboratory studies as criteria. The results showed tha t variations in alpha-power density in truck drivers, train drivers an d laboratory subjects could be predicted with considerable accuracy (r (2) > 0.70) from the model, as could subjective alertness. Levels less than or equal to 7 on the 16-point scale were defined as critically l ow alertness. The paper also describes a simplified, graphic, paper ve rsion of the computation model, visualized as a two-dimensional ''aler tness nomogram''. It is suggested that the studied components of the m odel may serve as tools for evaluating work/rest schedules in terms of sleep-related safety risks.