Falling asleep at the wheel, a constant danger that the car itself also provokes

According to a study carried out by a team of researchers at RMIT University in Melbourne (Australia), the low-frequency micro-vibrations generated by a moving car and transmitted to its passengers could be the main cause of the traditional drowsiness that occurs in them during long journeys.

Low-frequency micro-vibrations are transmitted constantly and directly to the body and brain of the vehicle’s passengers through their contact with the seats. This would be the main cause why most people start to feel sleepy when travelling in a car.

As a general rule, these micro-vibrations affect younger travellers, children, to a greater extent, which is why they are usually the first to feel the symptoms and fall into drowsiness. The micro-vibrations would also be what causes adult passengers to feel sleepy as the journey progresses. Drowsiness in them usually begins to manifest 20 minutes after starting the journey, with the most affected being the occupants of the rear seats, as they are further removed from the action and from the conversations between the driver and their companion.

The research carried out by scientists at the Australian university is based on the results of an experiment in which volunteers were seated in a simulator that reproduced the same type of low-intensity micro-vibrations that occur in cars and lorries on the road. The results of the research show that after fifteen minutes, the people under study progressively began to feel drowsy. After half an hour, the sensation of sleep became very evident, reaching its peak after 60 minutes.

Of all the passengers on board the vehicle, the driver would be the one with the greatest resistance to the effects of these micro-vibrations due to the existence of other types of vibrations that help keep him awake and alert for longer, and which he alone perceives thanks to his interaction with the steering wheel and other control instruments on board the vehicle. The driving sensations help him, but do not make him immune to the effect of the micro-vibrations, hence the need to respect the rest times at the wheel suggested by the traffic authorities: taking a 20-minute break every two hours.

The tiredness and fatigue are present in at least 30 percent of the accidents that occur on our roads according to data recorded by the DGT. Drowsiness is one of the symptoms of that tiredness and fatigue, but it is also behind many of the lapses of concentration that cause 40 percent of traffic accidents in Spain. Resting and sleeping well before a road journey helps to avoid them.

Avoidable causes that can lead to drowsiness at the wheel

But there are also many other causes that lead to drowsiness at the wheel. Excessive consumption of alcoholic drinks and certain medications also makes the driver sleepy while driving. Likewise, conditions such as sleep apnoea cause sudden and unexpected micro-blackouts in the driver, due to a lack of oxygen in the brain caused by circulatory problems that prevent blood from reaching the neurons normally. Obese people and those with respiratory problems (often caused by smoking or allergies) are particularly susceptible to the effects of apnoea while driving.

That is why, beyond the fact that a drive in the car is the solution many parents find to “put their children to sleep”, it is worth remembering now that the great car journeys we make on holiday are approaching, and the importance of having rested well, both before setting off and during the trip. As well as avoiding, as far as possible, postponing or spacing out rest stops. At the slightest sign of sleepiness, it is better to stop to rest or take a short walk that gets our circulation going and oxygenates our body. Having a coffee or a refreshing drink also helps.

Remember: at the slightest sign of drowsiness at the wheel, stop and rest. It is so important that brands such as Mercedes and many others now include icons such as the coffee cup (Attention Assist) on car instrument panels to tell drivers that it is time to take a break. The lighting up of these indicators on our dashboard is no trivial matter. There are vehicles equipped with systems that “monitor” the driver’s performance and their responsiveness, which read eyelid movements, analyse their trajectories and, depending on how long the car has been in use, allow these vehicles to warn their drivers and alert them to the need to take a rest stop during their journey. To do this, they use the combined information received from different sensors on board the vehicle, which, analysed and cross-referenced with the information received from the various driver assistance systems, allows it to determine that the driver is at the limit of their fatigue threshold, which indicates the need to stop.

Sundays in July, the days most prone to falling asleep at the wheel

Stopping every 2 hours, avoiding heavy meals or keeping up a conversation are some tips for avoiding drowsiness at the wheelSundays in July are the days that record the highest accident rate due to drowsiness at the wheel. More than one and a half million drivers say they have suffered one of these episodes at the wheel, and 55 percent of drivers admit to pushing on, resisting and forcing themselves to the limit to continue their journey, when what their body is asking for is to stop and rest for a while, according to data from a study carried out by the Línea Directa Foundation. The data shows that 20,600 accidents, with just over 800 fatalities, were caused by drowsiness at the wheel between 2011 and 2015, also leaving 3,300 seriously injured and 24,000 slightly injured.

According to the study, drowsiness at the wheel doubles the risk of death in the event of an accident. While normally 1.9 percent of traffic accidents end with at least one death, in the case of those where driver drowsiness is among the causes, this figure rises to 3.9%. Drowsiness at the wheel is behind at least 9 percent of road deaths in Spain. According to the study, the early hours of Saturday into Sunday during July on inter-urban roads is when this type of accident occurs most often, ending in serious run-off-road incidents and mostly affecting men between 21 and 30 years old.

To avoid drowsiness, the best thing, apart from the already mentioned rest every two hours or 200 kilometres, is to keep the vehicle well ventilated, drive with music that is not relaxing or while chatting with your companion, avoid heavy meals and, of course, alcohol before getting behind the wheel. It also helps to avoid, as far as possible, taking the car between three and five in the morning (hours when we usually go through our deepest sleep phases) and between two and four in the afternoon (the famous siesta hour).

When faced with symptoms of drowsiness, remember that besides a good rest stop, the best solution is to hand over driving to another driver whenever this is possible, or to stop and sleep for 15-20 minutes in a safe area away from traffic.