title: A Unified Model of Performance for Predicting the Effects of Sleep and Caffeine.
abstract: Existing mathematical models of neurobehavioral performance cannot predict the beneficial effects of caffeine across the spectrum of sleep loss conditions, limiting their practical utility. Here, we closed this research gap by integrating a model of caffeine effects with the recently validated unified model of performance (UMP) into a single, unified modeling framework. We then assessed the accuracy of this new UMP in predicting performance across multiple studies.
  
  
  
  We hypothesized that the pharmacodynamics of caffeine vary similarly during both wakefulness and sleep, and that caffeine has a multiplicative effect on performance. Accordingly, to represent the effects of caffeine in the UMP, we multiplied a dose-dependent caffeine factor (which accounts for the pharmacokinetics and pharmacodynamics of caffeine) to the performance estimated in the absence of caffeine. We assessed the UMP predictions in 14 distinct laboratory- and field-study conditions, including 7 different sleep-loss schedules (from 5 h of sleep per night to continuous sleep loss for 85 h) and 6 different caffeine doses (from placebo to repeated 200 mg doses to a single dose of 600 mg).
  
  
  
  The UMP accurately predicted group-average psychomotor vigilance task performance data across the different sleep loss and caffeine conditions (6% < error < 27%), yielding greater accuracy for mild and moderate sleep loss conditions than for more severe cases. Overall, accounting for the effects of caffeine resulted in improved predictions (after caffeine consumption) by up to 70%.
  
  
  
  The UMP provides the first comprehensive tool for accurate selection of combinations of sleep schedules and caffeine countermeasure strategies to optimize neurobehavioral performance.
authors.affiliation: Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, Fort Detrick, MD.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Ramakrishnan
authors.affiliation: Air Traffic Organization, Federal Aviation Administration, Washington, DC.
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Wesensten
authors.affiliation: Behavioral Biology Branch, Walter Reed Army Institute of Research, Silver Spring, MD.
authors.forename: Gary H
authors.initials: GH
authors.lastname: Kamimori
authors.affiliation: Behavioral Biology Branch, Walter Reed Army Institute of Research, Silver Spring, MD.
authors.forename: James E
authors.initials: JE
authors.lastname: Moon
authors.affiliation: Behavioral Biology Branch, Walter Reed Army Institute of Research, Silver Spring, MD.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Balkin
authors.affiliation: Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, Fort Detrick, MD.
authors.forename: Jaques
authors.initials: J
authors.lastname: Reifman
mesh_terms: D000293:Adolescent; D000328:Adult; D002110:Caffeine / Q000008:administration & dosage* / Q000009:adverse effects; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D011237:Predictive Value of Tests; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D012890:Sleep / Q000187:drug effects* / Q000502:physiology; D012892:Sleep Deprivation / Q000139:chemically induced / Q000175:diagnosis / Q000503:physiopathology; D007319:Sleep Initiation and Maintenance Disorders / Q000139:chemically induced / Q000175:diagnosis / Q000503:physiopathology; D014851:Wakefulness / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult
chemical_list: D002110:Caffeine
keywords: PVT; biomathematical model; caffeine model; chronic sleep restriction; total sleep deprivation