Tag Archives: Alertness

Driver sleeping.

Your car’s vibrations are making you a lousier driver — by lulling you to sleep

Just 15 minutes in a car makes us sleepier, affecting our ability to drive. After 30 minutes, this effect has a “significant impact on your ability to stay concentrated and alert,” researchers warn.

Driver sleeping.

Image via Pexels.

According to a new paper published by researchers from RMIT University in Melbourne, Australia, cars themselves may be a significant threat against our ability to drive safely — some 20% of fatal car accidents today involve driver fatigue, they explain, and, according to their research, the vibrations we experience in cars makes us sleepier, posing a major risk for motorists everywhere.

Snooze cruise

“We know 1 in 5 Australians have fallen asleep at the wheel and we know that drowsy driving is a significant issue for road safety,” said Professor Stephen Robinson, paper co-author. “When you’re tired, it doesn’t take much to start nodding off and we’ve found that the gentle vibrations made by car seats as you drive can lull your brain and body.

The team worked with 15 volunteers who were placed in a virtual driving simulator. The test pitted each participant against a monotonous, two-lane highway. It wasn’t the actual driving experience that was central to this experiment, however — what the team wanted to see was what effect car vibrations have on the volunteers’ alertness levels.

The simulator was installed on a platform that could vibrate on different frequencies. Each volunteer was tested twice, using the same 60-minute driving scenario, once with vibrations at low frequencies (4-7 Hz, the same range you’d experience in a car) and once with no vibrations (as a control test).

To gauge participants’ alertness, the team monitored their heartbeat. The researchers explain that tiredness induced by vibration makes it harder, both psychologically and physiologically, for people to perform mental tasks. In order to compensate, the body’s sympathetic nervous system alters the rate with which our hearts beat. So, by looking at each volunteer’s heart rate variability (HRV), researchers were able to gain an objective measure of how drowsy they were feeling as the test progressed.

Driving simulator.

The simulator rig used in the study.
Image credits RMIT University.

During the vibrating test, volunteers started showing signs of drowsiness roughly 15 minutes in. By the 30 minute mark, they showed significant drowsiness and required substantial effort to maintain alertness and cognitive performance. The effect was progressively stronger as the test drew on, peaking at 60 minutes.

Co-author Mohammad Fard, an Associate Professor at RMIT, said that the results warrant further research into the effect of these vibrations on people. One of the first areas that should be investigated is whether their effect is consistent across different demographics, he adds — as the current experiment used a relatively tiny sample size.

“We want to study a larger cohort, particularly to investigate how age may affect someone’s vulnerability to vibration-induced drowsiness as well as the impact of health problems such as sleep apnea,” he said. “Our research also suggests that vibrations at some frequencies may have the opposite effect and help keep people awake.

“So we also want to examine a wider range of frequencies, to inform car designs that could potentially harness those ‘good vibrations’.”

“To improve road safety, we hope that future car seat designs can build in features that disrupt this lulling effect and fight vibration-induced sleepiness,” added Robinson.

The paper “The Effects of Physical Vibration on Heart Rate Variability as a Measure of Drowsiness,” has been published in the journal Ergonomics.

Coffee cup.

More bang for your cup: new algorithm determines ideal caffeine intake for the best results

New research into the world’s favorite stimulant offers clues as to when and how much coffee you should drink to stay at peak performance.

Coffee cup.

Image credits Myriam / Pixabay.

Few things get you on your feet as effectively as a nice, warm cup of coffee. It’s not surprising, then, that the beverage is among the most widely-consumed in the world — and just like its main ‘competitor’, tea, there’s a rich culture surrounding it. But how much coffee should you drink to get the benefits without becoming a twitchy shell of a man?

Thanks to a new algorithm developed for the US Army, we now know exactly how much of it you should have to maximize alertness when experiencing lack of sleep.

Pvt. Coffee

“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,” said senior author Jaques Reifman, PhD.

Reifman, a senior researcher at the U.S. Army Medical Research and Materiel Command in Ft. Detrick, Maryland, and his team developed the algorithm starting from a mathematical model which predicts the effects sleep loss or caffeine intake has on psychomotor vigilance task (PVT) performance. This gave them the means to estimate what effects tiredness or a cup of coffee would have on a subject’s state.

PVTs are essentially simple response time tests. They were conducted at various times over several days and recorded alongside a subject’s caffeine-intake schedule.

The second part of the algorithm works from the raw data this mathematical model provides to determine how much caffeine that subject should consume to keep alertness at peak levels — even during sleep loss. Users provide their sleep/wake schedule and the maximum quantity of caffeine they’re willing to ingest, and the algorithm provides a dosing strategy tailored to their needs.

To test their system, the team computed dosing strategies used in four previously-published studies on sleep loss. Two strategies were generated and compared for each study — one to increase alertness (as measured by PVT performance) using the same amount of caffeine as the original study (maximizing effects) while the other aimed to achieve the same levels of alertness using a lower amount of caffeine (minimizing dosage).

“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,” Reifman explains.

“Alternatively, a subject can reduce caffeine consumption by up to 65 percent and still achieve equivalent improvements in alertness.”


The 2B-alert app follows a user’s sleeping patterns to predict alertness and cognitive performance levels throughout the day. Then it tells you when to take a shot of caffeine so you’re always running at full steam.
Image credits 2B-Alert.

According to the team, these results suggest that their algorithm can be used to determine the best timing and dosage for a particular sleep/wake cycle to maximize the benefits in alertness.

Although developed for military applications, the army knows that Monday mornings are just the worst and they’re willing to share. The US Army is currently looking to license the software, aiming to produce a commercial smartphone app for public use. The algorithm’s core functionalities will still be there, meaning it will monitor and learn your individual habits — a point that may put many off in this post-Cambridge Analytica scandal world. The app would potentially track and log fitness data to help improve results, as well.

If you simply can’t wait, an open-source version of the algorithm, dubbed 2B-Alert, is also currently available. It’s meant as a proof-of-concept, a limited demonstration of the final system. It takes into account sleep and caffeine-intake data (that you punch in), but won’t deliver personalized dosage strategies as it doesn’t include PVT data.

The paper “Caffeine dosing strategies to optimize alertness during sleep loss” has been published in the Journal of Sleep Research.