A cup of coffee and some sunshine can help sleep-deprived young drivers stay more alert while behind the wheel, according to research from the Queensland University of Technology in Brisbane, Australia.

The research was conducted by Dr. Shamsi Shekari of QUT's Centre for Accident Research & Road Safety. Shekari presented her findings at the 2016 International Conference on Traffic and Transport Psychology in Brisbane, a gathering of international experts to share road safety research aimed at reducing traffic-related injuries.

Shekari's study, conducted as part of her PhD, sought to determine whether bright light and caffeine could make young drivers more alert during daytime driving. The study used light glasses, which emit a shortwave blue-green light, as well as caffeinated chewing gum on drivers between the ages of 18 and 25.

Exposure to light can influence a person's circadian rhythms, a biological process which guides sleep cycles. Light therapy, or exposure to a bright light that simulates natural sunlight, is used to treat seasonal affective disorder as well as reduce sleepiness in pilots, night shift workers, and others who need to stay alert outside of daytime hours.

Caffeine can improve alertness by acting as a stimulant to the central nervous system. This compound blocks adenosine receptors in nerves, thus inhibiting the action of a biological compound that can cause fatigue.

The study was conducted over two weeks, with participants sleeping for eight hours a night in the first week. During the second week, chronic sleep deprivation was introduced by reducing each night's sleep to seven hours.

On the final three days of this week, Shekari monitored the participants' brain and heart activity, measured their reaction times, and assessed their sleepiness. Participants were also required to make two 50-kilometer drivers on a driving simulator.

In the first drive, participants were exposed to light and given chewing gum that did not have caffeine. The conditions were repeated in the second drive, except that some participants received caffeinated gum.

"Drivers who were given just caffeine, or light and caffeine together, had decreased side-to-side movement of the steering wheel and the vehicle, indicating better control of the vehicle and higher alertness," said Shekari. "Drivers who were feeling some signs of sleepiness after sleep loss felt less sleepy after receiving either light or caffeine, and even felt rather alert after receiving the combination of both."

Shekari said sleepiness is a factor in one out of every five crashes in developed countries. She said young drivers are more at risk for this kind of crash because they are more likely to be sleep-deprived.

"This is due to later brain development and social factors such as friends, work patterns, and increased use of drugs and alcohol, all of which impact on sleep," said Shekari.

The Governors Highway Safety Administration recently issued a report estimating that 83.6 million people in the United States drive while sleep-deprived, with an average of 6,400 traffic deaths a year in the U.S. attributed to drowsy driving. In 2014, the AAA Foundation for Traffic Safety determined that 21 percent of fatal vehicle crashes in the United States between 2009 and 2013 involved a fatigued driver.

Shekari said more research is needed to confirm the effect of light and caffeine on driver alertness. The Centre for Accident Research & Road Safety is currently studying the effect of sleep loss and caffeine on driving, with the specific intent of measuring the effect of both daytime drowsiness and caffeine on a driver's performance.