Twenty minutes or ninety#
Nothing in between
Last week, in one line#
A nap is not a small night’s sleep.
It is an entry into a sequence, and where you stop it decides what you get.
The sequence#
| Stage | Roughly | What it is |
|---|---|---|
| N1 | a few minutes | drifting off; easily denied |
| N2 | ~20 min in | light sleep, spindles |
| N3 | ~30–60 min in | slow-wave — the deep one |
| REM | ~70–90 min in | dreaming, back near the surface |
One lap: about ninety minutes.
Nap A — stop before N3#
- out at 20 minutes
- never reached slow-wave sleep
- alertness up, nothing to undo
The cheap one.
Nap B — finish the lap#
- out at ninety minutes
- came back up through REM
- wakes near the surface, where waking is easy
The expensive one, but it pays.
The dead zone#
Forty-five minutes is the worst nap available to you
Why#
Deep enough to be in slow-wave sleep.
Short enough that the alarm goes off while you are still in it.
You are not being woken from sleep. You are being extracted from it.
Sleep inertia#
The grogginess on the other side of that extraction.
- measurable on reaction time, not just on mood
- can exceed what the nap gave back
- worst where the nap was deepest
“I’m not a nap person.”
Usually a report of one forty-five minute nap, once, years ago.
Today’s lab#
- baseline — Karolinska, then reaction time
- nap, 20 minutes, timed from lights-down
- measure in the first two minutes
- measure again at fifteen
Entry one of your Nap Log.
Bring me your counter-example#
In a room this size, somebody wakes up worse.
That person is more interesting than the ones who confirm the reading.