Sleep Workshop: New Approaches to Modeling Sleep/Wake Dynamics and Cognitive Performance (October 26-27, 2006)
Partially supported by the AFOSR
Organizers: Janet Best, David Terman, and Hans Van Dongen
This workshop will address several important aspects of sleep/wake modeling, including interactions between the homeostatic and circadian processes; the link between sleep/wake dynamics, cognitive capabilities and performance; and how individual differences should be incorporated into the models. Although these questions have received previous study, earlier models have been largely phenomenological and thus far have not accounted for many important aspects such as the cumulative effects of chronic sleep restriction. Recent progress in understanding the neuronal and neurochemical substrates underlying the sleep/wake cycle, as well as the development of theoretical tools for analyzing complex biologically inspired models, makes this an auspicious time to forge new modeling approaches. The workshop will bring together a diverse and highly accomplished group of researchers across the spectrum from experimentation to mathematics. The workshop will focus on the link between sleep/wake regulation and human cognitive performance. It will provide a unique opportunity to exchange points of view, forge new collaborations and develop new approaches to modeling these important issues.
The workshop will address three primary themes:
- Modeling the homeostatic system and how it interacts with the circadian system: Most current models for sleep/wake regulation and for interactions between the circadian and homeostatic processes are directly or indirectly based on the seminal two-process model of sleep regulation. The two-process model has been successful in accounting for the effects of acute sleep deprivation on sleep and performance; however, the model has been less successful in accounting for experiments involving chronic sleep restriction and subsequent recovery sleep periods. This may be because the two-process model assumes that recovery during sleep occurs in an exponential manner; moreover the model assumes that the homeostatic and circadian processes are additive. More detailed models are needed to better describe the homeostatic process and account for the chronic sleep restriction experiments.
- Modeling the link between sleep/wake dynamics and cognitive/psychomotor capabilities: Most current models estimate the general trend of performance decline under conditions of sleep loss and/or circadian misalignment. There is evidence that sleep/wake alterations have differential effects depending on the nature of the performance task-which is not accounted for in contemporary models. Furthermore, time on task effects have thus far not been included. There is a need to develop models in which parameters have specific physiological and/or neuropsychological correlates, so that the behavior of the model may be interpreted biologically and interventions may be incorporated appropriately.
- Modeling individual differences: Sleep/wake and performance modeling thus far has focused on describing and predicting group-average responses. However, there is accumulating evidence for trait-like individual differences in responses to sleep and circadian challenges. Such systematic individual differences tend to represent a considerable portion of the variance and therefore need to be accounted for. It remains to be determined whether capturing individual differences would require variations in model structure or could be handled with subject-specific parameter settings. New modeling strategies are needed to address these important issues.
