EFFECTS OF ALCOHOL – what you should know for your MPU
The effect of alcohol on our brain
For your alcohol MPU you should also have examined how alcohol affects our perception and behaviour.
Alcohol enters our bloodstream and from there reaches every cell of the body and every organ. Alcohol can take effect particularly quickly in our brain, because this organ has such a good blood supply.
Reason versus needs
The cerebrum is the seat of our intellect and reason. All the norms and values we have learned in the course of our lives are stored here.
Our instinctive needs and feelings sit in the diencephalon.
Our cerebrum ensures that we do not simply give free rein to our instinctive needs and feelings, but restrain them so that we can express them within socially acceptable limits.
However, if our cerebrum restrains our needs and feelings too much, at some point they burst out of us. Many of us learned as children that we have to pull ourselves together and must not give free rein to feelings such as anger or desire. When sober, our excessive self-control makes us feel inhibited and our needs are neglected. Alcohol releases these suppressed and pent-up needs and feelings.
Suppressed needs and feelings take the upper hand
Drinking alcohol makes us feel more relaxed, less inhibited and happier. The control mechanisms of the cerebrum that keep our feelings and drives in check weaken. As a result, suppressed needs and longings and feelings such as anger and aggression can take the upper hand.
Reason seems to be switched off, and anyone who wants to drive after drinking will no longer be swayed by the rules of reason. When the cerebrum loses control completely under very large amounts of alcohol, this is known as a blackout.
When the effect of the alcohol has worn off the next day, the cerebrum takes the reins again and we resolve to control ourselves even better.
But this does not work out: if our feelings and needs are suppressed again and again, they will break out again as soon as the control mechanisms of the cerebrum weaken under the influence of alcohol.
The effect of alcohol on our vision
Alcohol paralyses our eye muscles and impairs the processing of visual impressions in the brain. As a result, visual disturbances can occur from as little as 0.3 ‰.
The field of vision narrows: every driver can only see what is happening around them within a limited field of vision. To see something outside this field, they have to turn their head. Alcohol narrows this field of vision so that you look as if through a tunnel without noticing. This can mean, for example, that a child running into the road after a ball is seen too late.
The gaze becomes sluggish: under the influence of alcohol our gaze can no longer move back and forth as quickly and stays fixed on one spot for longer. As a result, we miss important information.
Switching between distances is impaired: when driving, our gaze switches between different distances in a flash. Within a second we can see the traffic light turning red in the distance and the cyclist right next to us. Alcohol reduces our ability to judge distances correctly because communication between the left hemisphere of the brain, which controls the right eye, and the right hemisphere, which controls the left eye, is impaired.
We see double: when we fix our eyes on an object, two slightly different images of it are created: one from the right eye and one from the left. The brain combines both images into one picture with spatial depth. Under the influence of alcohol our eyes can no longer fix on an object at the same time and the two different images can no longer be combined in the brain, so we see everything double.
The pupil reaction slows down: when we drink alcohol, our pupil reaction slows down. Normally our pupils widen in the dark and contract reflexively in bright light. If we are dazzled by headlights while driving under the influence of alcohol, our pupils cannot contract quickly enough. We are dazzled and cannot see properly for a while.
Summary
Under the influence of alcohol our field of vision narrows.
Under the influence of alcohol our eyes can no longer move back and forth within seconds, and we miss important information.
Under the influence of alcohol our pupil reaction slows down and we are more easily dazzled.
The effect of alcohol on our movements
Depending on the amount drunk, alcohol affects our movements in different ways. Small amounts can impair fine motor skills – for example, it takes us longer to light a cigarette. If we drink a lot, we start to sway.
In small amounts, alcohol can make us feel less inhibited, looser, more relaxed and less anxious. We move more casually and gesture more when we talk. However, if we drink larger amounts, the parts of our brain that control our movements are also affected. Our movements become increasingly uncoordinated, we start to sway or walk unnaturally stiffly because we are trying not to trip or fall. When we are very drunk, we can hardly move at all: our face looks expressionless and we no longer move our arms and hands. At some point we can no longer put one foot in front of the other and can at most crawl, if at all.
Alcohol can make us more talkative. But the more we drink, the harder it becomes to speak. Speech disorders range from slips of the tongue and slurring to completely forgetting what we wanted to say.
The effect of alcohol on our fitness to drive
When driving, we have to carry out several movements at the same time and coordinate them. When moving off, for example, we have to find the biting point so as not to stall the engine. Under the influence of alcohol we can no longer manage fine movements.
We have already learned that under the influence of alcohol our eyes stay fixed on an object for longer. Since when driving we unconsciously steer in the direction we are looking, we drive towards the object our gaze is fixed on. To stay in lane, we have to make much stronger steering corrections than when sober. This can be seen in the fact that we drive in a zigzag.
Under the influence of alcohol we are also more likely to confuse the windscreen wiper lever with the indicator or accidentally drive with full beam. These supposedly small mistakes can also contribute to accidents.
The risk of an accident at 0.8 ‰ is four times as high as when driving at 0.0 ‰. Alcohol plays a role in every 10th minor road accident and in every 5th fatal road accident. Under the influence of alcohol, leaving the road can lead to collisions with other vehicles or objects. Rear-end collisions and scraping parked cars are also typical accidents under the influence of alcohol.
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