Dr. Matt Walker

And then I would say, even if you can fall asleep fine,

this factor of waking up in the middle of the night is also related to caffeine.

Why?

Because caffeine not only can make it harder to fall asleep, not your problem, but it keeps you out of that deep, deep sleep.

And it puts you into a more shallow state of non-rapid eye movement sleep.

And when you are in the shallow state, it's A, easier for you to be woken up.

But B, and I think more of the problem, it's harder for you to fall back asleep because your brain doesn't necessarily want to go back down into that deep sleep and nor has it come up out of that deep sleep.

So you're not in that wonderful, glorious, thick, treacly sort of sleepy state when you wake up, you go to the restroom, you come back and you just know, oh, this is gonna be great.

As long as I can fumble my way back to my mattress,

I'm going to be asleep within another two minutes going back to it.

Whereas for you, you probably wake up and you feel pretty wide awake.

I would like to see what happens when we negate that afternoon coffee on the frequency and the duration of those middle of the night awakenings for you.

Yeah.

So caffeine has something that we call a half-life of about five to six hours, meaning that after five to six hours, about 50% of that caffeine is still circulating in your bloodstream and thus your brain.

That means that caffeine has a quarter-life of somewhere between 10 to 12 hours.

Now, this is on average, and we'll come back to variations later.

But think of it this way.

If you're taking a cup of coffee, like you described there, at midday, and then you're going to bed at, let's say 11 or midnight, that would be the equivalent, based on what I've just told you, the quarter life

of getting yourself into bed.

And just before you took yourself into bed, you swig a quarter of a cup of coffee and you hope for a good night of sleep.