The coffee nap#
Drink first, then sleep
Last week, in one line#
A short nap works because it stops before slow-wave sleep.
This week: the one intervention that makes it work harder.
Adenosine#
- accumulates in the brain across the waking day
- binds to receptors that make you feel sleepy
- sleep clears it
The closest thing we have to a physical substance for tiredness.
What caffeine actually does#
It does not add energy.
It is shaped enough like adenosine to occupy the same receptors without activating them.
The tiredness is still there. It is still accruing. You just cannot feel it.
Twenty to thirty minutes#
The time a swallowed coffee takes to arrive
Two timelines#
| Moment | Adenosine | Caffeine |
|---|---|---|
| lights down | at the day’s high | swallowed, doing nothing |
| during the nap | sleep clears some | crossing over |
| on waking | less of it to feel | arriving at the receptors just cleared |
A nap of about 20 minutes and a cup of coffee finish at the same moment.
The order is the intervention#
Coffee, then sleep. Not sleep, then coffee.
Nothing about the coffee changes. Nothing about the nap changes.
Only when you take the first one relative to the second.
“That’s just folklore.”
Folklore does not usually come with an arrival time.
Where the evidence is thinner#
- the studies are small
- mostly on young adults
- mostly on simulated driving
The effect looks real. The size of it does not survive the retelling.
If you don’t drink caffeine#
You are not excused from this argument.
You are the control condition, and this week’s lab needs you.
Two timelines, not a magic drink#
A coffee nap beats a nap and beats a coffee, and the reason is arithmetic about two timelines rather than anything about coffee.