How long does caffeine stay in the body and when should the last cup of the day be drunk?

After discussing in a previous article about how coffee helps us focus and be more productive, it’s time to look at the other side of the coin. Every coffee lover has found themselves at least once in front of the famous ceiling looked at at midnight, wondering: «Was it a good idea to have coffee at 5pm?».

The relationship between coffee and sleep is complex, governed by biology and a small but powerful molecule called caffeine. To enjoy your favorite flavor without sacrificing rest, you need to understand how the coffee «clock» works in our body.

How does coffee affect our body?

To understand the impact on sleep, we need to know that a substance called adenosine accumulates in our body during the day. This is responsible for the feeling of tiredness; the longer we are awake, the more adenosine attaches to receptors in the brain, telling us it’s time to sleep.

Caffeine has an incredibly similar molecular structure to adenosine. When we drink coffee, caffeine occupies these receptors, blocking the tiredness signal. In essence, coffee does not give us new energy, but only «pauses» the brain’s ability to perceive accumulated tiredness.

The mathematics of sleep: half-life

This is where the technical part that few people know comes into play: the half-life of caffeine. On average, for a healthy adult, the half-life is approximately 5-6 hours. What does this mean?

If you drink a cup of coffee containing 100mg of caffeine at 4pm, at 10pm (when you might want to go to bed), 50mg of caffeine will be circulating in your blood. After another 6 hours, i.e. at 04:00 in the morning, you will still have 25 mg in your system. Although you may feel relaxed, your brain is still under the influence of a stimulant that can affect the quality of deep sleep, even if you manage to fall asleep.

When should the last coffee of the day be?

Most sleep hygiene specialists recommend consuming your last dose of caffeine at least 8-10 hours before going to sleep.

• If you go to bed at 10pm, the last «serious» coffee should be around 1 or 2pm.
• If you’re a «fast metabolizer» (those people who can drink an espresso and fall asleep immediately), you can push the limit to 4 p.m., but the quality of your REM sleep may still suffer.

It is important to remember that factors such as age, weight, genetics or even smoking can influence how quickly the body eliminates caffeine.

Solutions for afternoon coffee

If the ritual of drinking something warm and aromatic in the afternoon is too important to abandon, there is no need to despair. There are alternatives that won’t keep your eyes open until dawn:

1. Decaffeinated coffee: Modern decaffeination technologies keep the rich taste of the beans almost intact, eliminating over 97% of the caffeine.
2. Barley drink: The caffeine-free alternative that offers those roasted, earthy notes that many look for in coffee.
3. Herbal teas: A rooibos tea can be a great choice due to its slightly sweet notes.

Coffee is an incredible tool for performance and sensory enjoyment, but sleep is the foundation of our health. Get to know your rhythm and don’t let that last cup of the day rob you of the rest you’ll need to enjoy your coffee tomorrow morning. After all, the best coffee is the one drunk with a clear mind and a rested body!

What do you find at the Espresso Cafè for a quiet evening?

If you want to enjoy the taste of coffee even after the recommended time, we recommend you try our selection of decaffeinated coffee. Brands such as Lavazza, Illy or Bazzara offer decaffeinated versions through natural processes, which preserve the intense notes of chocolate and fruit, without affecting sleep.

And for the mornings when you want a gradual awakening, without the shock of a massive dose of caffeine, a coffee 100% arabica it is the ideal choice, having a much lower stimulant content than classic blends with Robusta.