Browsing by Author "Balkin, Thomas J"
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- Item2B-Alert App: A mobile application for real-time individualized prediction of alertness.(0000-00-00) Reifman, Jaques; Ramakrishnan, Sridhar; Liu, Jianbo; Kapela, Adam; Doty, Tracy J; Balkin, Thomas J; Kumar, Kamal; Khitrov, Maxim YKnowing how an individual responds to sleep deprivation is a requirement for developing personalized fatigue management strategies Here we describe and validate the 2B Alert App the first mobile application that progressively learns an individual s trait like response to sleep deprivation in real time to generate increasingly more accurate individualized predictions of alertness We incorporated a Bayesian learning algorithm within the validated Unified Model of Performance to automatically and gradually adapt the model parameters to an individual after each psychomotor vigilance test We implemented the resulting model and the psychomotor vigilance test as a smartphone application 2B Alert App and prospectively validated its performance in a 62 hr total sleep deprivation study in which 21 participants used the app to perform psychomotor vigilance tests every 3 hr and obtain real time individualized predictions after each test The temporal profiles of reaction times on the app conducted psychomotor vigilance tests were well correlated with and as sensitive as those obtained with a previously characterized psychomotor vigilance test device The app progressively learned each individual s trait like response to sleep deprivation throughout the study yielding increasingly more accurate predictions of alertness for the last 24 hr of total sleep deprivation as the number of psychomotor vigilance tests increased After only 12 psychomotor vigilance tests the accuracy of the model predictions was comparable to the peak accuracy obtained using all psychomotor vigilance tests With the ability to make real time individualized predictions of the effects of sleep deprivation on future alertness the 2B Alert App can be used to tailor personalized fatigue management strategies facilitating self management of alertness and safety in operational and non operational settings
- ItemCaffeine dosing strategies to optimize alertness during sleep loss.(0000-00-00) Vital-Lopez, Francisco G; Ramakrishnan, Sridhar; Doty, Tracy J; Balkin, Thomas J; Reifman, JaquesSleep loss which affects about one third of the US population can severely impair physical and neurobehavioural performance Although caffeine the most widely used stimulant in the world can mitigate these effects currently there are no tools to guide the timing and amount of caffeine consumption to optimize its benefits In this work we provide an optimization algorithm suited for mobile computing platforms to determine when and how much caffeine to consume so as to safely maximize neurobehavioural performance at the desired time of the day under any sleep loss condition The algorithm is based on our previously validated Unified Model of Performance which predicts the effect of caffeine consumption on a psychomotor vigilance task We assessed the algorithm by comparing the caffeine dosing strategies timing and amount it identified with the dosing strategies used in four experimental studies involving total and partial sleep loss Through computer simulations we showed that the algorithm yielded caffeine dosing strategies that enhanced performance of the predicted psychomotor vigilance task by up to 64 while using the same total amount of caffeine as in the original studies In addition the algorithm identified strategies that resulted in equivalent performance to that in the experimental studies while reducing caffeine consumption by up to 65 Our work provides the first quantitative caffeine optimization tool for designing effective strategies to maximize neurobehavioural performance and to avoid excessive caffeine consumption during any arbitrary sleep loss condition
- ItemCan a mathematical model predict an individual's trait-like response to both total and partial sleep loss?(2015-01-12) Ramakrishnan, Sridhar; Lu, Wei; Laxminarayan, Srinivas; Wesensten, Nancy J; Rupp, Tracy L; Balkin, Thomas J; Reifman, JaquesHumans display a trait like response to sleep loss However it is not known whether this trait like response can be captured by a mathematical model from only one sleep loss condition to facilitate neurobehavioural performance prediction of the same individual during a different sleep loss condition In this paper we investigated the extent to which the recently developed unified mathematical model of performance UMP captured such trait like features for different sleep loss conditions We used the UMP to develop two sets of individual specific models for 15 healthy adults who underwent two different sleep loss challenges order counterbalanced separated by 2 4 weeks i 64 h of total sleep deprivation TSD and ii chronic sleep restriction CSR of 7 days of 3 h nightly time in bed We then quantified the extent to which models developed using psychomotor vigilance task data under TSD predicted performance data under CSR and vice versa The results showed that the models customized to an individual under one sleep loss condition accurately predicted performance of the same individual under the other condition yielding on average up to 50 improvement over non individualized group average model predictions This finding supports the notion that the UMP captures an individual s trait like response to different sleep loss conditions
- ItemDose-dependent model of caffeine effects on human vigilance during total sleep deprivation.(2014-08-05) Ramakrishnan, Sridhar; Laxminarayan, Srinivas; Wesensten, Nancy J; Kamimori, Gary H; Balkin, Thomas J; Reifman, JaquesCaffeine is the most widely consumed stimulant to counter sleep loss effects While the pharmacokinetics of caffeine in the body is well understood its alertness restoring effects are still not well characterized In fact mathematical models capable of predicting the effects of varying doses of caffeine on objective measures of vigilance are not available In this paper we describe a phenomenological model of the dose dependent effects of caffeine on psychomotor vigilance task PVT performance of sleep deprived subjects We used the two process model of sleep regulation to quantify performance during sleep loss in the absence of caffeine and a dose dependent multiplier factor derived from the Hill equation to model the effects of single and repeated caffeine doses We developed and validated the model fits and predictions on PVT lapse number of reaction times exceeding 500 ms data from two separate laboratory studies At the population average level the model captured the effects of a range of caffeine doses 50 300 mg yielding up to a 90 improvement over the two process model Individual specific caffeine models on average predicted the effects up to 23 better than population average caffeine models The proposed model serves as a useful tool for predicting the dose dependent effects of caffeine on the PVT performance of sleep deprived subjects and therefore can be used for determining caffeine doses that optimize the timing and duration of peak performance
- ItemEffects of dextroamphetamine, caffeine and modafinil on psychomotor vigilance test performance after 44 h of continuous wakefulness.(2008-10-10) Killgore, William D S; Rupp, Tracy L; Grugle, Nancy L; Reichardt, Rebecca M; Lipizzi, Erica L; Balkin, Thomas JProlonged sleep loss impairs alertness vigilance and some higher order cognitive and affective capacities Some deficits can be temporarily reversed by stimulant medications including caffeine dextroamphetamine and modafinil To date only one study has directly compared the effectiveness of these three compounds and specified the doses at which all were equally effective in restoring alertness and vigilance following 64 h of wakefulness The present study compared the effectiveness of these same three stimulants doses following a less extreme period of sleep loss i e 44 h Fifty three healthy adults received a single dose of modafinil 400 mg n 11 dextroamphetamine 20 mg n 16 caffeine 600 mg n 12 or placebo n 14 after 44 h of continuous wakefulness After 61 h of being awake participants obtained 12 h of recovery sleep Psychomotor vigilance was assessed bi hourly during waking and following recovery sleep Relative to placebo all three stimulants were equally effective in restoring psychomotor vigilance test speed and reducing lapses although the duration of action was shortest for caffeine and longest for dextroamphetamine At these doses caffeine was associated with the highest percentage of subjectively reported side effects while modafinil did not differ significantly from placebo Subsequent recovery sleep was adversely affected in the dextroamphetamine group but none of the stimulants had deleterious effects on postrecovery performance Decisions regarding stimulant selection should be made with consideration of how factors such as duration of action potential side effects and subsequent disruption of recovery sleep may interact with the demands of a particular operational environment
- ItemIndividualized performance prediction of sleep-deprived individuals with the two-process model.(2008-02-11) Rajaraman, Srinivasan; Gribok, Andrei V; Wesensten, Nancy J; Balkin, Thomas J; Reifman, JaquesWe present a new method for developing individualized biomathematical models that predict performance impairment for individuals restricted to total sleep loss The underlying formulation is based on the two process model of sleep regulation which has been extensively used to develop group average models However in the proposed method the parameters of the two process model are systematically adjusted to account for an individual s uncertain initial state and unknown trait characteristics resulting in individual specific performance prediction models The method establishes the initial estimates of the model parameters using a set of past performance observations after which the parameters are adjusted as each new observation becomes available Moreover by transforming the nonlinear optimization problem of finding the best estimates of the two process model parameters into a set of linear optimization problems the proposed method yields unique parameter estimates Two distinct data sets are used to evaluate the proposed method Results of simulated data with superimposed noise show that the model parameters asymptotically converge to their true values and the model prediction accuracy improves as the number of performance observations increases and the amount of noise in the data decreases Results of a laboratory study 82 h of total sleep loss for three sleep loss phenotypes suggest that individualized models are consistently more accurate than group average models yielding as much as a threefold reduction in prediction errors In addition we show that the two process model of sleep regulation is capable of representing performance data only when the proposed individualized model is used
- ItemThe trait of Introversion-Extraversion predicts vulnerability to sleep deprivation.(2007-11-26) Killgore, William D S; Richards, Jessica M; Killgore, Desiree B; Kamimori, Gary H; Balkin, Thomas JAccording to Eysenck s theory of Introversion Extroversion I E introverts demonstrate higher levels of basal activity within the reticular thalamic cortical loop yielding higher tonic cortical arousal than Extraverts who are described conversely as chronically under aroused and easily bored We hypothesized that higher scores on the trait of Extraversion would be associated with greater declines in psychomotor vigilance performance during prolonged wakefulness We evaluated the relationship between I E and overnight psychomotor vigilance performance during 77 h of continuous sleep deprivation in a sample of 23 healthy adult military personnel 19 men four women ranging in age from 20 to 35 years At baseline volunteers completed the Revised NEO Personality Inventory NEO PI R and completed psychomotor vigilance testing at approximately 10 min intervals from 00 15 to 08 50 hours over three nights of continuous sleep deprivation In addition 12 participants received four repeated administrations of caffeine 200 mg every 2 h each night Analysis of covariance and stepwise multiple regression analyses showed that above and beyond the effects of caffeine higher Extraversion was significantly related to more extensive declines in speed of responding and more frequent attentional lapses but only for the first overnight testing session Sub factors of Extraversion including Gregariousness and higher Activity level were most predictive of these changes following sleep loss These findings are consistent with Eysenck s cortico reticular activation theory of I E and suggest that individual differences in the trait of Extraversion confer some vulnerability resistance to the adverse effects of sleep loss on attention and vigilance