How Caffeine Impacts Your Energy and Sleep

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Guest blog post by Johann Callaghan Author, Speaker, Educator, Busy Mum, Entrepreneur, Therapeutic Healing

Caffeine has been called the most popular drug in the world. This stimulant which can make it hard to fall asleep, is consumed on a daily basis in coffee, tea, cocoa, chocolate, some soft drinks, energy drinks and some drugs.

How Much Is Enough Caffeine?

Caffeine should be limited to mornings and early-mid- afternoons otherwise it may disrupt sleep patterns. Caffeine is a stimulant and it takes a long time to metabolise in the body for most people. It has a half life of 6 to 8 hours which means it takes half of the caffeine that amount of time to eliminate out of the system.

According to the Mayo Clinic, up to 400 milligrams (mg) of caffeine a day is safe to consume which is about 2 to 4 cups of coffee a day. A regular coffee can contain between 100-200mg of caffeine while and espresso can contain 240-700mg. While we mostly hear about the negative effects of caffeine, there are some benefits when used
in moderation. The right amount of caffeine can help you focus, but too much might make you jittery, anxious, or irritable.

How the Stimulating Effects of Caffeine Work

Caffeine’s main effect is on the brain. It’s very similar to adenosine which is the sleep inducing chemical in the brain. Caffeine binds easily to it and therefore blocks it. This inhibits the sleep drive which would normally relax the central nervous system and makes you feel tired. Adenosine gradually builds up during the day which gradually makes you feel more and more tired as the day goes on. This is especially true if you did not get a good night’s sleep the previous night. When this neurotransmitter (adenosine) is blocked, the body increases adrenaline and cortisol making you more active.

Caffeine also boosts dopamine levels in the brain, which controls the ability to focus and maintain concentration.

How Caffeine has an Impact on You

If you are a regular drinker of coffee, your body becomes tolerant to it. If you don’t drink coffee that much, one cup may make you more sensitive to its negative effects.

Caffeine has different impacts on everyone. The effects can last longer or shorter depending on factors like genetics, weight, age and if you are already using medications. For example, amphetamine medications cause the blood vessels to constrict which narrows the vessels. Caffeine causes dehydration, which also causes blood vessels to narrow. This restricts blood flow to the brain. In fact, that is why caffeine can mimic headache medications and may help to reduce them.

When you consume caffeine, it can take between 20 minutes and 1 hour to reach the bloodstream depending on these factors.

When Can Caffeine Make You Feel Tired?

Caffeine blocks the adenosine receptor which is what normally makes us feel tired.  Our bodies are quite intelligent and so it compensates by making more adenosine receptors. When most of the caffeine has worn off, guess what? Because there are excess adenosine receptors now, you will feel more tired. This is sometimes called a ‘crash’ because you get a hit of excess adenosine when the caffeine wears off.

In addition, caffeine is a diuretic and can leave you feeling dehydrated. If you drink coffee during the day, this will also make you feel tired. This is because your blood will thicken after losing water. Oxygen will then be slower to get around the body making you feel sluggish and tired.

Alternatives to Caffeine

There is a coffee that contains extracts of Ganoderma which according to Pub Med has many beneficial effects including purification of the blood and it helps to strengthen the immune system. Another alternative is black and green herbal teas.

While herbal tea may contain small amounts of caffeine, it also contains an aminoacid called L-Theanine. Although the caffeine content in teas gives that stimulating effect, the L-theanine can help to neutralise that. This amino acid can help slow down brain waves and alter aspects of the brain helping to reduce anxiety. These may be an
alternative to drinking regular tea and coffee.


For most people, drinking excess caffeine can disrupt the sleep-wake cycle and circadian rhythm. This is due to the length of time it takes for the caffeine to wear off and be eliminated by the body. It is important to note all the factors that can affect this.

Your genetic make up may affect how caffeine is broken down by your liver and medications may also react with caffeine. Drinking sugary caffeine drinks or taking sugar every time you have a cup of tea or coffee may lead to a sugar spike and then a crash.

Take note of all these things and find out how your body responds to caffeine.

If you feel that you are constantly low in energy, maybe you should talk to your doctor. Taking too much caffeine over a long period of time may have adverse affects and leave your adrenals very tired.

If you enjoyed this article and would like to know more, check out my upcoming book ‘How To Get A Good Night’s Sleep’.

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Guest blog post by Johann Callaghan

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