A start to the day without a hot cup of coffee is unimaginable for many people. The caffeine contained in coffee gets our circulation going and has a positive effect on our mood. On average, every German consumes around 200 milligrams of caffeine every day – in addition to coffee, intake also occurs via tea, cola, energy drinks and chocolate. Since caffeine has a stimulating effect, a cup of coffee or a glass of cola helps us overcome minor performance lows. But caffeine can also have side effects – especially if too much is consumed.
Effect of caffeine
Caffeine takes between 30 and 45 minutes to enter the bloodstream. Through it, it is distributed throughout the body before finally being excreted in the urine. The half-life of caffeine in the body is around four hours. In people in whom caffeine breakdown is slowed, such as pregnant women, the half-life can increase to as much as 20 hours. Caffeine has a broad spectrum of effects: In small doses, it has a primarily stimulating effect on the psyche – concentration is improved and symptoms of fatigue are eliminated. In addition, it also increases the brain‘s memory capacity. Caffeine can therefore have a positive short-term effect on learning performance during exams. In higher doses, caffeine also has an effect on the cardiovascular system. The intake of caffeine causes the heart to beat more frequently and more forcefully, which increases the pulse and blood pressure. However, the increase in blood pressure is minimal and occurs mainly in people who are not accustomed to caffeine.
Effect of caffeine on blood vessels.
Caffeine also has an effect on blood vessels: while blood vessels in the periphery dilate, vessels in the brain constrict – which is why caffeine can have a soothing effect on headaches or migraines. For this reason, some headache tablets now contain caffeine in addition to the active ingredients that relieve pain.
Caffeine and sports
The vasodilatation in the periphery also suggests a positive effect of caffeine on our athletic performance, as the muscles can be better supplied with oxygen. In addition, caffeine’s increased activity of the heart and dilation of the bronchial tubes may also have a positive effect on our performance.
The mechanism of action of caffeine
Many people take caffeine – whether in the form of coffee, energy drinks or caffeine tablets – to improve their alertness. The positive effect of caffeine on our attention and concentration is due to the fact that caffeine interferes with certain processes in our body. When our nerve cells are active, they consume energy, producing adenosine as a byproduct. The more the nerve cells work, the more adenosine is released. It ensures that the nerve cells in our brain do not overexert themselves. This happens because adenosine activates certain receptors that are responsible for conduction. When the receptors are activated, information is passed more slowly from nerve cell to nerve cell. Caffeine has a similar structure to adenosine and can therefore dock onto the same receptors. However, it only occupies the receptors without activating them. Consequently, no signal is sent to the nerve cells to slow down – the nerve cells therefore continue to work at full speed. However, through regular consumption of caffeine, the body becomes accustomed to the substance and the effect of caffeine on attention and concentration diminishes. This is due to the fact that the body forms more adenosine receptors over time, allowing the molecule to dock with some free receptors again. To achieve a performance-enhancing effect again, caffeine intake would have to be increased more and more.
Caffeine: side effects
When caffeine is consumed in larger amounts, a number of side effects can occur. These include:
- Sleep disturbances
- Headache
- Nervousness or
- Gastrointestinal complaints
Similarly, the consumption of caffeine can result in a loss of fine motor skills. Who regularly consumes caffeine, however, rarely suffers from the described side effects, because a habituation effect has already occurred.
Withdrawal symptoms from caffeine addiction
Anyone who regularly feeds their body high doses of caffeine over a long period of time can become addicted to caffeine. You can easily test for yourself whether you are suffering from caffeine addiction: if withdrawal symptoms occur when you reduce your caffeine consumption, you are addicted. The withdrawal symptoms that occur can include headaches and nausea, but also loss of energy and drowsiness. In addition, effects on mood must also be expected: A loss of drive and motivation, as well as depression-like states and irritability, are typical withdrawal symptoms. They set in about 12 to 24 hours after the last caffeine intake and can last up to nine days.
Caffeine overdose
An overdose of caffeine is said to occur when an amount of one gram of caffeine is consumed. Such a dose can result in a greatly accelerated pulse as well as extrasystoles (heartbeats outside the normal rhythm). It can also cause restlessness and insomnia. Some individuals may also experience anxiety due to excessive caffeine consumption. In the worst cases, a caffeine overdose can result in circulatory collapse.