Naps and memory#
Not rest. Filing.
Everything so far, in one line#
The nap has been recovery — something that undoes tiredness.
This week it does something else entirely: it processes what you learned.
Consolidation#
New memories start fragile and become durable over time.
- a good deal of that work happens during sleep
- not merely in spite of it
- visible as improvement without further practice
Two mechanisms, roughly#
| Stage | Associated with | The kind of thing |
|---|---|---|
| Slow-wave | stabilising declarative material | facts, events, things you could state |
| REM | procedural skill, recombination | doing it, and the bit that shows up as insight |
A nap long enough to include both is doing two jobs.
Which recalls week 2#
Nap length decides which stages you get.
So it decides which kind of consolidation you get.
20 minutes or ninety returns here — same choice, a different reason behind it.
Sleep before learning#
A rested brain encodes better.
- deprivation impairs the formation of memories
- not only their retrieval
- so the all-nighter damages the material studied during it
Sleep after learning#
Learned and then slept on beats learned and then spent an equivalent waking period.
A daytime nap produces a measurable version of that effect.
Both#
Sleep before you study and after you study
“I’ll sleep when the exam is over.”
The practice this displaces — studying instead of sleeping — is the one students reliably choose. Which is why the advice is unwelcome.
Reading the literature carefully#
This is the strongest experimental literature in the course. It is still literature.
- effect sizes are modest
- the tasks are laboratory tasks
- word-pair recall is not a degree
The direction is solid; the magnitude is routinely oversold.
Tell me this is a reward#
A nap after studying is not a reward for studying. It is part of the studying, and skipping it costs more than the time it would have taken.