Dr. Matt Walker

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.

And the chances are that it may not happen.

Now, again, that's a little bit sort of hyperbolic as a statement, but just try to conceptualize it in that way.

You would never think about taking on, you know, a last quarter cup of coffee just before you put your eye mask on.

And that no problem is in part this, I don't have an issue with falling asleep.

But if we were to, based on the data, map their electrical brain activity...

you would be able to see this reduction in the deep non-REM sleep.

And it can reduce it if you look at the data somewhere between 15% to 20%.

Now, for me to reduce your deep sleep by 15% to 20%, I would probably have to age you by about 20% to 22% years.