Coffee: How does caffeine wake you up?

Are you one of the one billion people who drink coffee daily worldwide? Well, you probably experienced the wonders of coffee and one of these is keeping you up!

Whether you need a kick in the morning, grab a drink on the go or plan an all-nighter to finish some work –coffee is always an excellent idea at any time of the day. 

All thanks to caffeine, we have that boost we need every day. A regular cup of coffee typically has around 95 mg of caffeine, which is enough to help you stay awake for several hours [1].

But, to begin with, how does caffeine actually work? 

What does caffeine do to your body?

Before we understand how caffeine works, we first need to be familiar with it. Caffeine is a natural psychoactive substance found in plants, including coffee beans, cacao pods, kola nuts, and tea leaves. 

To put it simply, caffeine is that bitter taste in your coffee. You can find caffeine in foods and standard drinks around the world, especially in coffee, as it is the most potent caffeinated beverage.

Caffeine can also be found in tea, soda, energy drinks, and cocoa or chocolate beverages. These drinks are rich sources of antioxidants and phytonutrients, which are technically suitable for your health.

Aside from these, caffeine can also be included in some minor prescription and non-prescription drugs like cold and allergy medications and pain relievers [2].

One of caffeine’s health benefits is reducing the risk of developing neurological disorders, especially Parkinson’s and dementia. 

What does caffeine do?

What does caffeine do?

Caffeine has similarities to a chemical in your body called adenosine that slows down the rate at which your nerves fire.

This sleep-promoting chemical can build up in the brain as you stay awake for a long time, and when this happens, as you might expect, you become sleepier.

Caffeine interferes with this chemical’s slowing effect on your brain; hence, your neurons remain active and vigilant instead of winding down. 

As a result, caffeine can make you alert and energized, and for some of us, it helps us concentrate.

However, there are times, usually for those with low caffeine intolerance, when the effects of caffeine are harmful, like anxiety, restlessness, insomnia, and increased heart rate

Caffeine is a stimulant that affects your central nervous system, and the effects can be felt as early as just 15 minutes after you enjoy your cup of joe. Caffeine can peak in the blood for up to 2 hours and remain there for 9 hours as your liver breaks it down [3].

However, several factors must be considered when determining its time effect on a person. If you are smoking or have caffeine tolerance, the stimulant effects could be reduced, and the breakdown of caffeine can be faster.

On the other hand, the caffeine effects can be the opposite for people taking oral contraceptives or who are pregnant.

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Which type of coffee has most caffeine?

As mentioned, caffeine can be found in various sources, but the most popular one is coffee. For an 8-ounce cup of coffee, there are 80-100 milligrams of caffeine. And, of course, it varies depending on the coffee you drink [4].

  • Brewed coffee: There is around 70-140 mg of caffeine in every 8-ounce cup for this type of coffee. The coffee beans are brewed in hot water and usually sit in a paper, metal, or plastic filter. 
  • Cold brew coffee: A 12-ounce cup of this coffee has 153-238 mg of caffeine. The difference with brewed coffee is that it is made without heat. 
  • Decaffeinated brewed: The myth of this coffee is that most of us think it has no caffeine–that’s wrong. Decaffeinated coffee, also known as decaffeinated coffee, still has caffeine in its composition but at lower levels. In every 8-ounce cup of decaf coffee, there is around 0-7 mg of caffeine, and it contains an average of 3 mg. 
  • Espresso coffee: This type of coffee is considered to be the strongest one among the others because it has more caffeine volume. Espresso is made by forcing hot water or steam through very finely ground coffee beans. Although it has a high amount of caffeine, its servings are small; it is estimated that every 30-50 ml has 63 mg of caffeine. 
  • Espresso-based drinks: Lattes, cappuccinos, macchiatos, and Americanos are just some of our favorite drinks that can be regularly bought in coffee shops. All of these have espresso shots mixed with a considerable amount of milk. Milk generally contains no caffeine; however, espresso contains 63 mg of caffeine and 125 mg for large servings. 
  • Instant coffee: This one contains less caffeine compared with brewed coffee, considering most of us actually consume this. An 8-ounce cup of instant coffee has an estimated 62 mg of caffeine. Instant coffee is the easiest to prepare since you just need to add the coffee powder with hot water. 

How can caffeine affect your sleep?

As most of us have responsibilities, events to attend, and many other reasons to stay awake, there are numerous instances when we greatly depend on caffeine to keep sleepiness at bay. In this situation, we disrupt our sleeping patterns with caffeine. 

Most of us have sleeping patterns, as our biological rhythm guides us when to sleep and when to wake up.

This sleep-wake pattern is considered one of our body’s circadian rhythms and commonly operates on a 24-hour cycle. The so-called circadian rhythms refer to physiological ways in which our body responds to our environment. 

As explained, caffeine’s classic effect is to keep you awake for several hours; caffeine binds with sleep-promoting receptors in your brain, preventing it from telling your brain that you need sleep. Unfortunately, caffeine in our body will not stay there forever [5].

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. This is commonly around 4 to 5 cups of brewed coffee, ten cans of soda, or two shots of energy drinks. Experts suggest that with this amount of caffeine, there are no dangerous or harmful side effects to experience.

Significantly, you will not develop any brain and digestive problems. Although caffeine has its perks, it can cause several problems for you, too. 

Furthermore, caffeine’s major negative effect is that it can cause sleep deprivation in people who constantly consume it.

There are also strong tendencies to feel fatigued at all times, develop sleeping problems like insomnia, struggle with memory, and problems with regulating emotions [7].

Surprisingly, some people become sleepy when taking caffeine; this is because caffeine gives them the feeling of tiredness rather than being alert. The truth about caffeine and sleep is that it becomes a cycle when you depend too much on it. 

As caffeine can cause sleep deprivation for a day, you will probably feel tired and want to sleep more the next day you wake up; you will want to consume caffeine to fill the need–and this is how the caffeine dependency starts. It’s time to end the cycle and make sure you get the rest you need.

There is a recommended cut-off time for caffeine intake if you are thinking of when to drink and when not to.

A minimum of 6 hours before bedtime is recommended if you want to balance your caffeine consumption

To know if you are overusing caffeine or becoming fully dependent, you should look for these signs: 

  • Constant headaches
  • Having anxiety during the day
  • Trouble sleeping during the night (frequent awakenings and trouble getting back to sleep)
  • Nighttime anxiety
  • Excessively sleepy during the day
  • Fatigue and tiredness
  • Low energy

While most of us have incorporated drinking caffeine into our daily routine, we need to be aware that too much can be bad news for our sleep, mood and health. Keep an eye on the number of cups of coffee you drink to prevent its possible adverse side effects. 

Is there such a thing as too much caffeine?

What does it mean to be caffeine-sensitive?

Caffeine sensitivity varies widely among individuals, influenced by genetic factors, age, and body composition.

Some people can consume large amounts without adverse effects, while others experience jitteriness or sleep disturbances even with a modest intake.

Genetic variations in enzymes responsible for caffeine metabolism affect how quickly or slowly caffeine is broken down in the body.

Age also plays a role, with younger individuals often more sensitive to caffeine’s stimulating effects.

Additionally, body weight can influence sensitivity, as caffeine’s impact may be stronger in those with lower body mass.

Understanding your sensitivity and tolerance to caffeine is essential for responsible consumption.

Pay attention to your body’s signals and adjust your caffeine intake to enjoy its benefits while minimizing potential side effects.

Closing thoughts

Caffeine, the active component in coffee, is a powerful tool for awakening our senses and boosting alertness.

Interfering with adenosine’s calming signals in the brain sparks increased mental clarity, enhanced mood, and heightened physical performance.

However, consuming coffee responsibly is crucial, considering individual variations in caffeine sensitivity and potential long-term effects. Finding the right balance and timing for coffee intake can optimize its wake-up benefits.


How does caffeine wake you up?

Caffeine wakes you up by blocking adenosine, a neurotransmitter that promotes sleepiness, increasing alertness and improved focus.

How much caffeine does coffee make you wake up?

The amount of caffeine in coffee that makes you wake up can vary from person to person. Still, generally, a moderate intake (about 100-200mg) can provide wakefulness without causing excessive jitteriness.

Will coffee actually keep me awake?

Yes, coffee can keep you awake due to its stimulating effects on the central nervous system. Still, it’s essential to consume it in moderation and be mindful of individual tolerance to avoid sleep disturbances.

Does coffee wake up your brain or body?

Coffee primarily wakes up your brain by inhibiting adenosine receptors, which promotes mental alertness and cognitive function, although it can also have some physical effects, like increased heart rate.

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