You’re in bed by half past eleven. Tired enough, you haven’t done anything weird, no screens on anymore, and all the curtains are closed.
And yet it takes three quarters of an hour before you’re out, or you just fall asleep normally, but wake up the next morning feeling like something is missing.
There’s a chance it’s because of that cup of coffee you had at three in the afternoon.
How sleepiness actually works
From the moment you wake up, a substance called adenosine builds up in your brain. The longer you’re awake, the more of it there is, and the more of it there is, the sleepier you get.
That’s your sleep pressure. It’s like a scale that slowly fills up all day, and by evening it’s heavy enough to make you fall asleep. While you sleep, your body clears away that adenosine again, so you start the morning with an empty scale.
That’s how it’s supposed to go.
What caffeine does to that
Caffeine is similar enough in shape to adenosine to fit into exactly the same spots in your brain. It gets in there and takes up the space.
The key word is takes up the space. Caffeine doesn’t remove the adenosine, it just makes sure you don’t feel it. Meanwhile, your scale just keeps filling up, only the needle stays still.
And as soon as the caffeine wears off, everything that built up in the meantime still comes through. That’s exactly that moment around five o’clock when you suddenly feel completely drained.
Why three in the afternoon is too late
Your body needs roughly five to six hours to break down half of the caffeine. Half, not all of it.
If you drink a cup of coffee at three, there’s still half a cup in your body around nine in the evening, and if you go to sleep at half past eleven, there’s still a fair amount left.
That pace differs quite a bit from person to person, by the way. One person breaks down caffeine twice as fast as another, and that’s largely genetic. That’s why your colleague can drink espresso at eight in the evening and sleep like a log, while a cappuccino after lunch already throws you off.
The most annoying part is this. You usually just fall asleep, so you think it doesn’t affect you. What you don’t notice is that your deep sleep becomes shorter and that you wake up more often for a brief moment without realizing it. You sleep the same number of hours, they just give you less back.
And then you wake up tired, drink a bit more coffee in the morning to make up for it, and find yourself in exactly the same situation a day later.
What you can do about it
Have your last coffee at noon. Around twelve o’clock, at the latest two o’clock. Then most of it will be gone by the time you go to sleep.
Also look at what you don’t think of as coffee. Black and green tea, cola, energy drinks, pre-workout, and dark chocolate all contain caffeine. A bar of 80% after dinner still counts.
Test it on yourself instead of copying a rule. Set your last cup to twelve o’clock for a week and see what happens. If you feel nothing, then you’re one of the fast metabolizers and you can still have a cup later in the day just fine.
And if your coffee timing is sorted but you still wake up tired, then the problem is the quality of your night. Mouth breathing does exactly the same as caffeine, it makes your night shallower without you waking up from it. If you breathe through your mouth during the night, your heart rate goes up a bit, which means you don’t fully get into those deep phases of the night. Mouth tape keeps your mouth closed and nasal strips keep your nasal passage open with a splint, so your body keeps breathing through your nose.
The habit for this week
Your last coffee at twelve. Seven days, nothing else in your day changes.
Set an alarm on your phone if you’re worried you’ll forget, because most people pour that afternoon coffee on autopilot. Me too :)
After a week, pay attention to how quickly you fall asleep and how you feel in that first hour after waking up. Those are the two things that change first. Still just as tired? Then at least you know it’s not your coffee, and you can look further into what you eat in the evening.
Every Night 1% Better.
Guy Veeke
PS: Coffee earlier in the day and still waking up tired?
Then it could be related to how you breathe. The combination of nasal strips and mouth tape keeps your nose open and your mouth closed, so those hours actually do something for you.
