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Effects of Caffeine on the mind and body

Updated: Jul 8, 2021

Caffeine is the most consumed drug in the world and is probably part of your morning ritual to kick start your day. Caffeine is naturally found in some foods but is most commonly consumed in drinks such as tea, energy drinks and coffee. Many of us reach for coffee as a reliable method of alleviating our tiredness and increase our alertness with great affect consistently throughout the day, which begs the question; Is this healthy?

Since caffeine is a drug, meaning it has a physiological effect on the body, it is important to know what affect it is having on your mind and body and what a healthy daily dose is.

Mood and Cognitive Behaviour Caffeine works by stopping the effect of messengers that alert the brain that it is tired and increases the release of feel good messenger in the brain such as serotonin and dopamine. In a healthy and rested individual these affects increase the alertness, reaction time and short term memory as well as decreasing the bodies perception of being fatigued and this is the ‘buzz’ felt after coffee and it is shown that this caffeine peak occurs approximately 60 minutes to 90 minutes after consumption. Interestingly the amount of caffeine required is relatively low to begin these positive cognitive affects with only 12.5mg of coffee required and the max recommended is 400mg. To put this into perspective in one espresso shot (30ml) there is 60-80mg of coffee so having anywhere between half a coffee and 4 coffees will bring on the positive effects. Excessive amounts (>400mg of caffeine) of caffeine consumption however cause and increase risk of headaches, dehydration, anxiety and sleep disturbances.

Physical Performance

Moderate caffeine intake as mention above is considered to be approximately 175mg to 400mg has shown to have positive effects on physical performance whilst exercising. It is thought that the caffeine increases the rate and amount of muscle contractions and also increases an individuals tolerance to feeling fatigued. The decrease in how fatigued the individual feels has been attributed to up to 30% of the performing enhancement caused by caffeine.


It is common knowledge that caffeine is known to have a diuretic effect or in other words, caffeine dehydrates you, but interestingly enough research shows that even though caffeine does have an effect on the kidneys it is only significant in high doses of more than 400mg of caffeine per day or greater than four coffees per day. Less than this amount was found not to have a clinical effect on hydration.

In order to maximise the benefits and minimise the risk of caffeine it is recommended to have between 1-8 cups of tea and 0.3 to 4 cups of coffee per day (400mg max per day). There is still much speculation about the long term effects of caffeine and the effects of withdrawal from caffeine. It is also important to recognise that this particular article has not included other caffeine based effects on other parts of the body such as an individuals metabolism, the heart and kidneys therefore it is important to seek clarification from a medical professional if you have any medical conditions that could heighten or dampen the effects of caffeine. Moderation is key.

There are many other ways of combating fatigue and tiredness including a balanced diet, good life and work balance and regular exercise so come in and speak to our friendly staff at WA Health Group to give you the natural pick me up you are looking for.


Ruxton C.H.S. The Impact of Caffeine on Mood, Cognitive Function, Performance and Hydration. British Nutrition Foundation. 2008, 33, 15-25.

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