Dynamic Circadian Modulation in a Biomathematical Model

1987 Mathematical Model of Fatigue and Performance—McCauley et al INTRODUCTION Building on the seminal two-process model of sleep regulation,1,2 biomathematical models for the prediction of fatigue, behavioral alertness and performance during periods of sleep deprivation and/or circadian misalignment instantiate a homeostatic process seeking to balance time asleep with time awake, and a circadian process seeking to place wakefulness during the day and sleep during the night.3 Such fatigue models have become useful tools in modern fatigue risk management systems.4 To capture the temporal dynamics of waking neurobehavioral performance across a wide range of sleep/wake schedules, we recently introduced a new class of fatigue models, formulated in terms of coupled first-order ordinary differential equations (ODEs).5 A specific implementation of the new model class, using scheduled time in bed (TIB) as input, was calibrated and validated5 with large datasets of neurobehavioral performance from laboratory-based dose-response studies of sleep loss.6,7 The dynamics of this new fatigue model5 indicated that prior sleep history modulates the homeostatic equilibrium state for sleep/wake regulation,8,9 and therefore the magnitude of the effect of subsequent sleep restriction on neurobehavioral performance.10 This prediction has since been corroborated DYNAMIC CIRCADIAN MODULATION IN A BIOMATHEMATICAL MODEL