For a large majority, coffee is an indispensable part of everyday life.
Indeed, well known for its stimulating effects on the brain, coffee likes to accompany us in the morning to give us a little boost with breakfast.
But is its effectiveness the same throughout the day?
Can we drink coffee in the evening?
To understand the action of coffee on the human body, we must first understand how it works.
EFFECT OF COFFEE ON HORMONES
The human body has a complex nervous system that is highly autonomous.
The study of biological rhythms is called chronopharmacology.
It considers the functioning of the cicardial clock, the 24-hour “internal clock” that affects different behaviors in the body, such as temperature, heart rate, and hormone production. It can affect the tolerance and effectiveness of certain drugs.
Good knowledge and mastery of our natural clock are essential because it allows us to understand better how our body works and thus adapt our desires to our needs.
Every morning, the body wakes up thanks to cortisol, also known as the “stress hormone.”
The cortisol level in the nervous system varies according to the hours of the day and night: for a person with a conventional lifestyle, it is at its highest in the morning, between 7 and 9 am.
This is when it is at its highest and most stable and decreases throughout the day to reach its lowest level in the evening.
This released energy contributes to awakening, vigilance, and thus to the regulation of our internal clock.
The caffeine contained in coffee acts especially on cortisol by stimulating its production and increasing its effects.
Drinking coffee during peak cortisol hours has an ineffective action because the effects produced are the same, at a time when the individual’s alertness is already at its peak.
There is even a risk of the opposite effect than expected: drinking a cup of coffee when waking up could reduce, in the longer term, the effects of all the cups of coffee drunk, i.e., being a victim of coffee resistance.
Similarly, drinking more than 4-5 cups of coffee a day is no longer effective, as the body has already absorbed the amount of caffeine it needs to stay awake.
There are also other times of the day when the cortisol level in the blood peaks again, often between 12 and 1:30 p.m. and then again between 5 and 6:30 p.m.
This rhythm may vary slightly from person to person, so it is best to drink your coffee outside these hours to make sure it is really effective.
EFFECT OF COFFEE ON SLEEP
If coffee is the second most-consumed drink globally, after water, it is obviously for its stimulating action that awakens and allows an efficient functioning of the brain.
However, in addition to its ineffectiveness during cortisol peaks, it is strongly advised not to consume caffeine 6 hours before sleep, i.e., at the end of the afternoon.
Indeed, the presence of caffeine has a strong effect on the time of falling asleep, but also on the sleep phases:
it disrupts the brain’s action and makes it difficult to reach the deep sleep stage.
Sleeping after drinking coffee would therefore be less restful and cause feelings of fatigue throughout the day.
Drinking coffee in the evening is therefore strongly discouraged for people suffering from sleep disorders.
WHEN IS THE BEST TIME TO DRINK COFFEE?
We have seen that the human body produces its own cycles of sleep and energy.
For example, the effectiveness of coffee is at its peak if it is consumed after 9 am or before 6 pm, during periods of falling cortisol levels.
As its effectiveness is long-lasting, it should be avoided after 6 pm to avoid any sleep disorders and benefit from a complete and restorative sleep.
Thanks to this article, you will now know what time to take your coffee to take advantage of all its effectiveness!
For more information on the effect of coffee on health, you can also read our dedicated article on this subject.