A group of U.S. Army researchers developed a web-based tool that tells users when and how much caffeine they should consume to feel most alert during the day.
Is a 7 a.m. espresso your answer to springing into action, or would waiting until midmorning leave you more alert? Will an afternoon cup of coffee help you avoid that post-lunch slump, or will it keep you wired all night long?
The guesswork of exactly when and how much caffeine to consume to help us stay alert during important tasks may be a problem of the past, thanks to a new web-based tool developed by U.S. Army medical researchers that helps you determine how much caffeine you should consume and when to optimize your alertness throughout the day.
The researchers evaluated the effectiveness of the tool in a group of more than 900 U.S. military members. Data showed that compared with caffeine doses recommended by current U.S. Army guidelines on optimal caffeine use, the new tool’s suggestions either cut caffeine doses by 40 percent (but still allowed individuals to achieve the same level of alertness, as measured by psychomotor vigilance tests) or enhanced alertness by as much as 40 percent. The data were presented in San Antonio last week at Sleep 2019, the annual meeting of the Associated Professional Sleep Societies (which includes both the American Academy of Sleep Medicine [AASM] and the Sleep Research Society), and the data was also published in an abstract in an April 2019 issue of the journal Sleep.
Service members are often sleep deprived, which is why the Army has been studying how they respond and perform in that state for decades, says Jaques Reifman, PhD, who is a Department of Army senior research scientist for advanced medical technology based in Maryland and a principal investigator of the study.
According to the National Sleep Foundation, more than 40 percent of active duty military members are sleeping five or fewer hours per night. This is significantly less than the seven or more hours of sleep a night recommended by the Centers for Disease Control and Prevention (CDC) for best health.
So it’s not surprising that the Army is trying to improve recommendations for caffeine optimization. Caffeine is a psychoactive stimulant that acts on the central nervous system to increase energy, and research has established its benefits in terms of memory, sharpening focus, and even powering physical activity.
Determining the minimal dose required for optimal alertness benefits is important, because too much caffeine can lead to some less-than-desirable effects (as anyone who’s had one too many cups of coffee can attest). Risks of overdoing it include: restlessness and shakiness, headaches, dizziness, dehydration, anxiety, and upset stomach, according to the National Institutes of Health and Mayo Clinic.
“Our tool allows an individual (in our case our service members) to optimize the beneficial effects of caffeine, while minimizing its consumption,” Dr. Reifman says.
The Caffeine Algorithm Is Based on Decades of Research
To develop the caffeine-optimizing algorithm, the researchers used data from a variety of previous sleep-deprivation research that informed them when and how much caffeine did and did not boost alertness and performance.
“Many of the studies looked at how sleep deprivation affects alertness and performance and how caffeine can counteract that for a short period of time,” says Reifman. Sometimes the subjects were sleep deprived on a daily basis or placed in situations where they were intentionally sleep deprived for up to 60 hours or more, says Reifman.
On the basis of an analysis of these studies, researchers developed mathematical models that they then tested and validated for a decade, Reifman explains. At the Sleep 2018 annual meeting in Baltimore, Reifman presented data (that was also published in the April 2018 issue of the journal Sleep) comparing the resulting algorithm with the caffeine-dosing strategies of four previously published experimental studies of sleep loss. Those results found that the algorithms the researchers had come up with boosted neurobehavioral performance in individuals by up to 64 percent, or allowed individuals to maintain similar levels of alertness while reducing caffeine consumption by 65 percent.
For the new study, the researchers created the online tool, 2B-Alert Web 2.0. It generates an optimized caffeine schedule for its users based on the caffeine-guidance algorithm along with several factors that the users input themselves: desired peak-alertness periods, minimum desirable level of alertness, and the maximum tolerable daily caffeine intake. The tool recommends doses of caffeine in terms of milligrams (which can be consumed in any form).
The tool can also predict the “average” person’s alertness based on his or her sleep/wake schedule and caffeine schedule.
Even without an optimal night of sleep, the tool can tell you the minimal amount of caffeine to achieve the maximum benefit, Reifman explains. “If you need to be at peak alertness between 9 a.m. and 5 p.m., the 2B-Alert will tell you the most effective amount of caffeine and the right times to consume it.”
The 2-B Alert Web 2.0 tool is freely available online to the public. (After completing a short registration that includes an email address, the user is sent a password and username.)
The researchers also turned the tool into a mobile app for research purposes, but that version is currently only available to active military members, Reifman says. The researchers are now exploring options that would further customize the app for non–military members and make it available to consumers, Reifman says.
It’s worth noting that the 2B-Alert Web 2.0 algorithm was developed with reference to data gathered from people between ages 18 and 40 who were military members. That means that, while the tool is available online to everyone, further research is needed to determine whether the recommendations are appropriate and effective for individuals outside that demographic (including older individuals), Reifman says.
Even the Perfect Espresso Schedule Can’t Make Up for Lost Sleep
This is important work with a lot of data behind it, says Nitun Verma, MD, a sleep medicine physician in private practice in San Francisco and a spokesperson for the American Academy of Sleep Medicine (AASM).
Maximizing alertness and minimizing delays in response time can mean the difference between life and death in certain military situations, he says. But there are potentially positive implications if this type of tool could be used outside the military, too, he adds.
“I think this tool would also be really helpful for people who are shift workers in fields where it’s important to stay alert, such as nurses, commercial truck drivers, and air traffic controllers,” Dr. Verma says.
He points out that the tool was developed using information gathered from the military population, who are typically more compliant and physically fit than the average population. But he adds that that fact isn’t a strong limitation of the study.
Verma also points out some important warnings from the AASM on caffeine use: Besides losing sleep, there can be some side effects associated with too much caffeine, including diarrhea, nausea, and heart palpitations. You should limit your caffeine intake to no more than about 300 to 400 milligrams (mg) per day and try to avoid consuming it in the afternoon or evening.
And remember that sensitivity to caffeine varies by individual. The algorithm in this tool personalizes optimal caffeine use for specific sleep-wake schedules and desired time of alertness, not necessarily for your specific caffeine sensitivity, he says. And in general caffeine stays in our systems longer than people think, Verma says.
“The half-life of caffeine is six hours, which means if you drink a cup of coffee at noon, half of that cup of coffee is still in your system at 6 p.m.,” says Verma. It also means that at midnight there’s a quarter cup of coffee in your body. “That’s something that’s usually very surprising for my patients, because it’s not intuitive to think that coffee would stick around so long in our body,” says Verma.
And finally, remember that no amount of caffeine (no matter how optimal) can substitute for poor or inadequate sleep, Verma says. Sleep has numerous short- and long-term health benefits in addition to keeping you alert and awake each day. “Caffeine doesn’t fix everything,” he says. “Even perfectly timed caffeine won’t remove sleep debt.”
Becky Upham
MAY