Author: Luke Sholl
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Cu peste 10 ani de experiență în crearea de conținut despre CBD și canabinoizi, Luke este un jurnalist consacrat care lucrează ca scriitor principal pentru Cibdol și alte publicații despre canabinoizi. Angajându-se să prezinte conținut autentic real, bazat pe dovezi, pasiunea sa pentru CBD se extinde și în domeniul fitness-ului, nutriției și prevenției bolilor.
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What is caffeine?

For many, nothing beats the first coffee of the day. But what is it about tea, coffee, energy drinks, and chocolate that makes them so great at boosting energy levels? Well, the answer rests with caffeine, a naturally occurring stimulant. Keep reading to find out more.

What exactly is caffeine?

Caffeine is a naturally occurring stimulant in coffee, tea, cacao plants, and guarana. However, what makes caffeine unique is its effect on the mind and body. Consuming caffeine stimulates the brain and central nervous system (CNS), increasing alertness and helping prevent and combat tiredness (most of the time).

In fact, caffeine's mildly stimulating effects make it one of the world's most commonly consumed psychoactive substances. As much as 80% of the world's population consumes a caffeinated product every day, and the first use of caffeine (brewed tea) dates back as far as 2737 B.C.[1]

Nowadays, caffeinated energy drinks dominate a significant portion of our caffeine intake. The only problem is these drinks contain substantial levels of sugar and other potentially harmful substances, which often gives caffeine a bad reputation by association. However, as we'll discover shortly, caffeine consumed in moderation may have far more wellness pros than cons.

How does caffeine work?

The influence of caffeine is vast, affecting both the central nervous system and the brain. However, the substance's stimulating effects stem from its impact on the brain, specifically, the hormone adenosine.

During the day, adenosine levels climb, and the neurochemical binds with adenosine receptors to encourage tiredness and help you sleep. Caffeine effectively blocks this interaction by binding with the same receptors but not activating them.[2]

The interaction above, combined with an uptick in dopamine and norepinephrine, round off caffeine's energising influence. And, even better, this all starts happening after roughly half an hour, thanks to how easily (and quickly) caffeine reaches the bloodstream via your gut and liver.

How long does caffeine stay in your system?

While it may only take 30–60 minutes for caffeine to reach full effectiveness, it stays in your system longer than most people think.

Caffeine has a half-life of around 5–6 hours, meaning if you consume 20 milligrams, 10mg remain in your system after 6 hours. However, any remaining caffeine can take up to 12 hours (depending on metabolism and other factors) to completely leave the body.

Because of caffeine's extended and often unknown time in the body, it's best to avoid drinking coffee, tea, or energy drinks after midday. This way, your body has plenty of time to clear the stimulant from your system before it's time to sleep.

Potential benefits of caffeine

We mentioned earlier that caffeine is often seen as a harmful substance, when in reality, the stimulant can offer several wellness benefits.

Caffeine and alertness

A 2016 paper titled "A review of caffeine's effect on cognitive, physical and occupational performance" outlined the benefits and possible shortcomings of caffeine.[3]

The study found that "doses up to approximately 300mg enhance a wide array of basic cognitive functions", adding that "caffeine is an effective strategy to counter both physical and cognitive decline associated with sleep loss".

However, there were several areas where caffeine was found lacking. For example, the impact of caffeine appears dose-dependent, meaning you need to think about how much you're consuming and when you're consuming it to get the most benefit. The researchers also found that the "effects of caffeine on higher-order executive skills, complex judgment, and decision-making are unclear".

Caffeine and memory

The relationship between caffeine and memory is fascinating because it isn't as simple as consuming coffee and gaining improved memory function. Instead, the memory benefits may stem from the precise timing of caffeine consumption, according to a 2010 study.[4]

Over 80 college students were asked to memorise 40 pairs of words. Some drank a placebo before they studied, while others drank a caffeinated drink. The following day they were given the same drinks (either placebo or caffeinated) and asked to recall as many pairs as possible.

The students who drank different beverages on both days couldn't remember as many pairs as those who consumed caffeine or the placebo. While this doesn't clearly identify caffeine's influence on memory, it does suggest a "state-dependent memory when caffeine is used".

Caffeine and fatigue

On the one hand, caffeine boosts energy levels, alertness and arousal by blocking adenosine receptors. However, caffeine's interaction with the nervous system can actually contribute to fatigue, rather than help banish it. High doses of caffeine "taken 0, 3, or even 6 hours prior to bedtime significantly disrupt sleep", perpetuating the cycle of fatigue and tiredness.[5]

Caffeine and metabolism

A 1980 study of caffeine on metabolic rates makes some interesting observations about the short-term influence of coffee. The evidence suggests that "caffeine/coffee stimulates the metabolic rate in both control and obese individuals", adding that "this is accompanied by a greater oxidation of fat”.[6]

However, before you start increasing your caffeine intake to burn off fat, it's important to note that the metabolic rate only increases for up to 3 hours after drinking caffeine. You also need to factor in the tolerance-building aspects of caffeine. During long-term consumption, the body builds a tolerance, meaning we need to consume more caffeine to get the same effect. As such, the long-term benefit of caffeine for metabolism remains under review.[7]

Dosing caffeine

We've talked extensively about the importance of caffeine dose and timing. While timing is generally easier to manage, knowing how much coffee or tea you should be drinking isn't as straightforward.

The US Department of Health and Human Services recommends up to 400mg of caffeine per day for general everyday consumption.[8]

In practical terms, this equates to roughly:

• 2–4 cups of coffee
• 10 cans of cola
• 2 energy shots

Keeping caffeine intake below the threshold highlighted above is not associated with "increased long-term health risks among healthy individuals". For most of us, there is very little to worry about if you've grown to love a cup or two of coffee every morning.

Side effects of caffeine

The possible side effects of caffeine typically fall into one of two camps—those experienced from an excess caffeine intake, and those experienced from caffeine withdrawal. Symptoms of the former include:

• Restlessness/shakes
• Insomnia
• Dehydration
• Dizziness
• Anxiety

If you regularly consume caffeine, the body can become dependent, leading to withdrawal effects if you suddenly stop. The severity of withdrawal symptoms varies from person to person, but the good news is they typically only last a week.

Caffeine withdrawal symptoms include:

• Irritability/low mood
• Anxiety
• Difficulty focusing
• Fatigue
• Headaches

The best approach for those who want to reduce their caffeine intake is to cut back slowly. If you usually drink three cups of coffee a day, limit yourself to two cups for a week, before dropping to a single cup.

When to avoid caffeine

Despite the prevalence of caffeine in modern diets, there are some circumstances where the compound's stimulating effects cause significant issues. It's best to avoid caffeine if any of the following applies:

• Migraines or chronic headaches
• Sleep disorders (insomnia)
• Mood disorders (anxiety)
• High blood pressure
• Pregnant or breastfeeding
• On prescription stimulants or heart medicines

Ultimately, you will know best how your body responds to the effects of caffeine and whether the stimulant is suitable. Of course, if you have any questions or concerns about the suitability of caffeine, withdrawal symptoms, or how to cut back, then a doctor or physician should be your first port of call.

Why caffeine can be good for you

There's no escaping the fact that caffeine is one of the most widely consumed stimulants in the world. For many of us, it would be hard to imagine starting the day without a cup of coffee or tea.

Fortunately, caffeine offers a wealth of potential wellness benefits. Provided you take a moderate approach to caffeine consumption, there's little reason to worry about the long-term impact. Just remember, everyone's tolerance for caffeine differs, and lifestyle, medication, metabolism and even sex play a part in how it makes you think and feel.

You can experience a high-quality range of caffeine-infused wellness supplements when visiting the Cibdol store. Or, to learn more about healthy lifestyle habits, see our CBD Encyclopedia for everything you need to know.


How much caffeine is in a cup of coffee?
A single cup of coffee usually contains around 95mg of caffeine. However, that range can fluctuate from 0 to 500mg per cup.
How long does caffeine last?
Caffeine starts working in 30–60 mins, with the stimulant present in the bloodstream for a further 5 hours. Residual amounts remain for up to 12 hours.
How much caffeine should you have in a day?
For healthy adults, the daily recommended maximum intake is approximately 400mg (roughly 2–4 cups of coffee).
How much caffeine can you have while pregnant?
Pregnant or breastfeeding mothers should limit their caffeine intake to a daily maximum of 200mg (roughly 1–2 cups of coffee).
Why does caffeine make me tired?
Caffeine blocks adenosine from binding with receptors, but when the effects wear off, the build-up of adenosine still exists and can lead to tiredness.

[1] Heckman MA;Weil J;Gonzalez de Mejia E; M. Caffeine (1, 3, 7-trimethylxanthine) in foods: A comprehensive review on consumption, functionality, safety, and regulatory matters. Journal of food science. Published 2010. Accessed June 7, 2022. [Source]

[2] S; F. An update on the mechanisms of the psychostimulant effects of caffeine. Journal of neurochemistry. Published 2008. Accessed June 7, 2022. [Source]

[3] McLellan TM, Caldwell JA, Lieberman HR. A review of caffeine's effects on cognitive, physical and occupational performance. Neuroscience & Biobehavioral Reviews. Published September 6, 2016. Accessed June 7, 2022. [Source]

[4] Kelemen WL, Creeley CE. State-dependent memory effects using caffeine and placebo do not extend to Metamemory. Taylor & Francis. Published 2010. Accessed June 7, 2022. [Source]

[5] Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine. Published November 15, 2013. Accessed June 9, 2022. [Source]

[6] Acheson KJ;Zahorska-Markiewicz B;Pittet P;Anantharaman K;Jéquier E; K. Caffeine and coffee: Their influence on metabolic rate and substrate utilisation in normal weight and obese individuals. The American journal of clinical nutrition. Published 1980. Accessed June 7, 2022. [Source]

[7] Kelemen WL, Creeley CE. State-dependent memory effects using caffeine and placebo do not extend to Metamemory. Taylor & Francis. Published 2010. Accessed June 7, 2022. [Source]

[8] Scientific report of the 2015 dietary guidelines advisory committee. Advisory Report. Published 2015. Accessed June 7, 2022. [Source]

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