2B-Alert app 2.0: personalized caffeine recommendations for optimal alertness.

Abstract

If properly consumed, caffeine can safely and effectively mitigate the effects of sleep loss on alertness. However, there are no tools to determine the amount and time to consume caffeine to maximize its effectiveness. Here, we extended the capabilities of the 2B-Alert app, a unique smartphone application that learns an individual's trait-like response to sleep loss, to provide personalized caffeine recommendations to optimize alertness. We prospectively validated 2B-Alert's capabilities in a 62-h total sleep deprivation study in which 21 participants used the app to measure their alertness throughout the study via the psychomotor vigilance test (PVT). Using PVT data collected during the first 36h of the sleep challenge, the app learned the participant's sleep-loss response and provided personalized caffeine recommendations so that each participant would sustain alertness at a pre-specified target level (mean response time of 270ms) during a 6-h period starting at 44h of wakefulness, using the least amount of caffeine possible. Starting at 42h, participants consumed 0 to 800mg of caffeine, per the app recommendation. 2B-Alert recommended no caffeine to five participants, 100-400mg to 11 participants, and 500-800mg to five participants. Regardless of the consumed amount, participants sustained the target alertness level ~80% of the time. 2B-Alert automatically learns an individual's phenotype and provides personalized caffeine recommendations in real time so that individuals achieve a desired alertness level regardless of their sleep-loss susceptibility.