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Chapter 3 specific trait parameters (e.g., rate of homeostatic decay, magnitude of circadian fluctuation in performance, etc.) prior to predicting future performance with an individual-specific model.

The Circadian, Neurobehavioral Performance, and Subjective Alertness Model approach has been directed towards increasing the accuracy of predictions and adding operationally relevant features. For example, melatonin is now incorporated as a circadian marker rhythm to accurately predict the phase and amplitude of the circadian pacemaker. Incorporation of wavelength-specific inputs is in progress. This model has recently been amended to allow the determination of an optimal light countermeasure regime for a given shift in sleep/wake or work schedule to improve performance at a desired time; this includes a schedule/countermeasure design prototype program that allows a user to interactively design a schedule and automatically design a countermeasure regime.

A current BHP in-flight effort is collecting sleep-wake data through use of actigraphy. These data, which are accumulated from actual astronauts in flight, will be integrated into the Circadian, Neurobehavioral Performance, and Subjective Alertness Model. 116