Morning coffee — Friend or foe of sleep?

While we enjoy a good cup of coffee for its comforting taste, it’s the caffeine it contains that gives it its stimulating power [1]. Once consumed, this molecule quickly enters the bloodstream and reaches the brain, where it blocks adenosine, a substance that promotes relaxation and sleep [2]. Bingo! We feel more awake, focused and energized. But this effect does not stop when the excitement subsides: caffeine can remain active in the body for many hours, delaying the onset of sleep and disrupting its quality, especially in more sensitive individuals. And once the effect of the caffeine has worn off, the build-up of adenosine can cause… sleepiness!

Caffeine is not only found in coffee. It’s also in tea, matcha, energy drinks, soft drinks like cola, mate, guarana and even in some chocolates. Its concentration varies depending on the type of drink: one cup of filtered coffee may contain 80–120 mg of caffeine, whereas black tea has around 40–60 mg and a matcha has approximately 30–70 mg [1]. Energy drinks, however, are restricted by regulation to 180 mg per serving [3]. 

Health Canada recommends that healthy adults should not exceed 400 mg of caffeine per day, or about three cups of coffee. Exceeding this amount can lead to nervousness, palpitations, sleep disorders and many other side effects. It should also be noted that some medications contain caffeine or may interact with it [6]. Before taking any over-the-counter medication containing caffeine, it’s best to check with your pharmacist to see if it could affect you. If it’s a prescription drug, the pharmacist will let you know! 

We often hear that matcha and green tea contain L-theanine, an amino acid (a molecule) that may smooth out the stimulating effect of caffeine, resulting in more sustained alertness, without excitation peaks. Some studies suggest that the natural combination of caffeine, L-theanine and catechins found in matcha and green tea may provide a gentler, more sustained stimulation, with less effect on sleep than coffee [4–5]. But be careful! Beverages that contain L-theanine artificially added as a supplement don’t seem to offer the same benefits… even if we like to claim they do! 

But how much is “too much”? Researchers think that consuming an average of 191 mg of caffeine a day, or about two cups of filter coffee, is already enough to start disrupting sleep quality [6]. And that’s not all: one study pointed out that regular coffee drinkers can lose around 45 minutes of sleep, and, what’s more, this sleep becomes less restorative [7]. 

But beware – caffeine isn’t just hidden in coffee! A large latte (16 oz or 500 mL) can contain around 150 mg of caffeine, while a can of energy drink contains between 80 and 180 mg. Even a few cups of black tea (about 50 mg per cup) or a matcha (30–70 mg) can add up over the course of the day [1]. The higher the dose, the longer caffeine acts as a stimulant, delaying drowsiness and fragmenting sleep. What’s worse, too much caffeine can affect deep sleep, which is essential for true recovery [8]. So, if you drink too much caffeine, you may regret it once you are cozy in bed!

And it’s not just a question of quantity: some people metabolize (eliminate) caffeine more slowly, which means that a single cup in the morning can still have a lasting effect in the evening. A key element to understanding this variable effect of caffeine is its half-life. This rather complicated scientific term refers to the time it takes for the body to eliminate half the caffeine consumed [6].

For example, if our half-life is five hours and we drink a large coffee containing 100 mg of caffeine, there will still be 50 mg left after five hours, then 25 mg five hours later, and so on.

The fact is, however, that the half-life of coffee varies greatly from one person to another [1–6]. Some people eliminate caffeine in as little as 2 hours, while others can keep it in their body for over 12 hours. The result? For some people, an afternoon coffee will be completely eliminated before the evening, while for others, the effects will still be felt at bedtime. On average, the half-life of caffeine in a healthy adult is between 2.5 and 5 hours [6], but it’s best to listen to your body to know where you fall on the caffeine metabolism scale!

Replacing our afternoon coffee with another warm, comforting beverage can be an excellent way to smoothly transition to the evening. Here are a few options:

• Green tea: With 20 to 45 mg of caffeine per cup, it’s rich in antioxidants and L-theanine, an amino acid that helps reduce the stimulating effects of caffeine.
• White tea: Very low in caffeine, it offers a subtle and light experience, ideal for those who prefer a delicate beverage.
• Oolong tea: It contains less caffeine than green tea, but more than white tea, offering a happy medium for those looking for a little more energy without too much excitement.
• Rooibos: Completely caffeine-free, this red tea from South Africa is a perfect soothing drink at the end of the day
• Infusions: Classics like chamomile, mint and lavender are all caffeine-free and seem to provide a sense of calm and relaxation.
• Decaffeinated mate: For a full-bodied taste without the stimulation of caffeine, this option provides a nice alternative that is still easy on the body.
• Matcha: Although richer in caffeine (60 to 70 mg per cup), it also contains a significant amount of L-theanine, which tempers the stimulating effect of the caffeine. It’s an interesting compromise, but it’s important to try it to see how it affects your body.
• Decaffeinated coffee: An interesting option for those who enjoy the taste of coffee without the effects of caffeine. However, it’s important to know that the decaffeination process, which can be performed using solvents, water or carbon dioxide, alters the taste of the coffee. If you’re looking for an alternative that is closer to regular coffee, it may be worth exploring different brands and processes to find the one that best suits your taste buds.

We don’t all metabolize caffeine at the same rate, and several factors beyond our control come into play. Genetics is one of the main culprits: some people have ultra-efficient liver enzymes that eliminate caffeine in no time at all, while others take their time, prolonging its stimulating effects. Age and health also make a difference: a healthy liver eliminates caffeine more efficiently than an unhealthy one. Furthermore, lifestyle comes into play: smokers eliminate caffeine faster, while pregnant women and those taking hormonal contraceptives retain it longer in their bloodstream. Depending on your profile, a cup of coffee can be a simple boost to an energized day or an invitation to a sleepless night.

We all wish we could eliminate caffeine faster, but our body sets its own pace, and there’s no magic solution to force it to go faster! 

However, our coffee drinking habits influence how it affects us: if you are a heavy coffee drinker, you may develop a certain tolerance, which gradually lessens its effects. The result? You have to drink more coffee to feel awake. But beware, changing a well-established routine can cause a few headaches. The best approach, therefore, is to listen to your body and adjust your consumption based on how it reacts. If caffeine disrupts your sleep, it’s best to observe when it starts to take effect… and avoid drinking it too late. In short, a little trial and error to find the right balance for you!

• Restrict caffeine consumption after 1:00 p.m.: To reduce the impact of caffeine on our ability not only to fall asleep but to ensure a good night’s sleep, it’s best not to consume caffeine at the end of the day (Gardiner). Your body will thank you!
• Explore caffeine-free alternatives in the afternoon: Replacing coffee with relaxing infusions or lattes made from plant-based beverages and spices can be an excellent way to help smoothly transition to the evening.
• Maintain a regular sleep routine: Going to bed and getting up at the same time every day can be a more important determining factor in sleep quality than the type of beverage consumed. According to the experts, we should aim for 7 to 9 hours of sleep per night.
• Listen to your body: If you experience signs of anxiety or agitation, it’s crucial not to ignore them. It’s very important to adjust our caffeine intake according to our individual needs. Experimenting is key to finding the right balance.