When should you have your coffee?

Written by Alfie Gleeson

A new algorithm can tell you exactly when to take in caffeine to stay alert.

Researchers from the Department of Defense Biotechnology High Performance Computing Software Applications Institute, Fort Detrick (MD, USA) have developed an algorithm that delivers optimal caffeine dosing strategies. The work, included as an abstract in a supplement of Sleep, helps to provide strategies that can maximize alertness for those suffering with sleep deprivation from a variety of conditions.

Caffeine is consumed everyday all over the world. It is one of the most common stimulants used to wake people up and keep them alert throughout the day. However, mistiming a caffeine dose can lead to sleepless nights, restlessness and overtiredness. Therefore, the time at which the caffeine is administered is crucial to its performance as a stimulant. The algorithm developed by the team does just this, as author Jaques Reifman, senior research scientist at the US Army Medical Research and Materiel Command (MD, USA) explains,

“We found that by using our algorithm, which determines when and how much caffeine a subject should consume, we can improve alertness by up to 64 percent, while consuming the same total amount of caffeine. Alternatively, a subject can reduce caffeine consumption by up to 65 percent and still achieve equivalent improvements in alertness.”

The algorithm takes a sleep schedule and a maximum caffeine dose as inputs and outputs a dosing strategy.

To create the algorithm, the team utilized a model that predicts the effects of caffeine and sleep loss on psychomotor vigilance task performance (PVT). These tests determine reaction time to visual stimulation. Often, they consist of a light appearing/disappearing on a screen; the participant must press a button as soon as the light appears on the screen.

The researchers took this model and combined it with a computationally efficient optimization algorithm to find out what the safe dose is to maximize alertness.

To test the algorithm, the group used existing data from published studies of sleep loss. The algorithm generated two strategies for each data set, one that enhanced PVT using the same caffeine doses and one that achieved the same PVT performance but with lower doses.

Overall, when the new algorithm was used, PVT performance was enhanced by 64% and caffeine doses were decreased by 65% for the respective experiments.

“Our algorithm is the first quantitative tool that provides automated, customized guidance for safe and effective caffeine dosing to maximize alertness at the most needed times during any sleep-loss condition,” Reifman concludes.