After demonstrating the link between diet and vigilance, and the impact of certain foods on the level of drowsiness, the Prevention Insurance association this time sought to know if caffeine helps fight drowsiness at the wheel. And for good reason, it is the leading cause of death on the motorway, the most risky hours being between 1 p.m. and 3 p.m. and 2 a.m. and 5 a.m. The objective: to study the impact caffeinated drinks with people tested in real driving situations using a simulator. Because knowing that nearly 6 in 10 French people have a coffee when they feel tired behind the wheel, it is better to know if this reflex improves alertness or if it is a received idea.
The study consisted of testing three groups with consumption of different drinks: a control group “decaffeinated espresso” (50 cl, without caffeine), a group “Double espresso coffee” (160 mg of caffeine) and a “caffeinated drink” group (160 mg of caffeine). The experiment was carried out on a driving simulator in the morning on an empty stomach, each participant having to first perform a 15-minute exercise on a closed road to take control of the simulator. Then the instruction was to practice 30 minutes of highway driving with a braking exercise, before enjoying a 15-minute break with the drink. The last step was to “drive” 120 minutes on the motorway with 3 braking exercises.
Coffee promotes alertness while driving
As explained by Dr Frédéric Saldmann, cardiologist and nutritionist, “unexpected braking exercises during the driving session allowed evaluate the reaction time some participants. »Two other parameters were used to assess the effects of caffeinated drinks on alertness at the wheel: a regular self-assessment of the sleepiness of each participant and a second-by-second analysis. of the state of vigilanceThe participants thanks to a very advanced visual control system. Study results show that coffee and other caffeinated drinks help fight drowsiness and related loss of alertness. long journeys on highways.
Concretely, it turns out that coffee is effective in almost completely preventing occurrence of micro-sleeps throughout a two hour driving session. “This is a crucial point since these two states (known drowsiness and micro-sleeps) are obviously the most accident-prone. », Says Prevention Insurance. The “decaffeinated espresso” control group, which absorbed many substances present in coffee, overall achieved the poorest performance. The researchers then wanted to better understand the origin of this beneficial effect of coffee, whose composition counts no less than 1000 different molecules.
Besides caffeine, a beneficial “synergistic effect”
The best known are: metylxanthines derived from caffeine (theobromine and theophylline), diterpenes (cafestol, kahweol), trigonelline, chlorogenic acids (of which coffee is the main source in human food) and flavonoids (ferulic acid and caffeic acid). But the association points out that the caffeine level being the same in the “coffee” group and in the “caffeinated drink” group, caffeine alone does not explain the significant difference in favor of coffee. The explanation lies in the fact that it would be the “synergistic” effect of all the molecules it contains which is positive on alertness at the wheel, and not isolated caffeine.
It remains, according to her, to identify precisely the molecules involved in this synergy. “Our study shows that coffee is effective for long-lasting against drowsiness at the wheel, whereas for a long time it was believed that it only gave a punctual boost. However, behavior remains more essential than ever for safe driving. », Concludes Stéphane Pénet, administrator of Assurance Prévention. Taking coffee is therefore part of the other good gestures known to fight drowsiness at the wheel, starting with leaving rested and to stop every 2 hours and at the first sign of drowsiness. The driver must also hydrate well, ventilate his vehicle and, as previous Insurance Prevention studies have shown, eat light while avoiding fatty and sugary foods.