Eleven Hours and Still

Morning~

Haaah~

…Good morning. What time did you go to sleep?

Midnight! Netsuki DID keep her promise♪ Slept a whole eleven hours!

…eleven hours.

Netsuki made a promise five days ago — go to sleep at a normal time. And Netsuki kept it!

…kept it.

Haaah~~

…Netsuki.

Hmm?

…is your sleep actually enough, nya?

What! Netsuki’s got extra to spare(ﾟ∀ﾟ)

…you’ve yawned three times since you woke up.

Isn’t it weird to be sleepy even after sleeping too much? Like, Netsuki is clearly on the world-champion side for hours slept!

…sleeping too much lands close to the same result as not sleeping enough, nya.

Wait, what?!

…there’s a study with 1.3 million people’s data. Using 7-hour sleepers as the baseline — sleep ≤6 hours and mortality goes up 10%. Sleep ≥9 hours and it goes up 30%, nya.

Sleeping too much has HIGHER mortality?!

…U-shaped curve. Too little and too much are both bad. The middle is safest, nya.

…Netsuki is at eleven hours right now.

…right end of the U, nya.

Not sleeping enough is dangerous, sleeping too much is dangerous — so when do we just get to live?

…seven hours, nya. Bottom of the mortality valley.

Okay but why is the number something weird like seven or eight hours? Wouldn’t a round number like ten hours make way more sense?

…ninety minutes, nya.

Ninety minutes?

…while you sleep, your brain cycles between light and deep sleep. One loop takes about ninety minutes, nya.

…wake up right when a cycle ends and you’ll feel refreshed. Wake up in the middle and your head stays foggy.

So ninety minutes times five cycles… that’s 450 minutes. 7.5 hours.

…nya. That’s what “seven and a half hours of sleep” is actually based on.

So Netsuki’s eleven hours — which cycle does Netsuki wake up on?

…partway through cycle seven, nya.

…so Netsuki woke herself up in the middle of a cycle, and that’s why everything’s foggy.

…more hours doesn’t mean more complete cycles. Sleeping longer doesn’t mean waking up better, nya.

Mm — come to think of it, Netsuki just remembered something. There’s this sleep researcher Matthew Walker, and his book says — keep sleeping only six hours and after ten days your cognitive level drops to the same as pulling an all-nighter

…Why We Sleep.

Why We Sleep (2017), bestseller! Netsuki remembers it!

…that book is in a scuffle, nya.

What?

…in 2019, a young researcher named Alexey Guzey published a rebuttal. Said the book was full of errors and exaggerations, nya.

The most famous book in sleep science is disputed?!

…mismatches between citations and the actual text, graphs with axes cut to support the argument, cherry-picked data shaped around the conclusion he wanted to make, nya.

…Netsuki believed all of it.

…it’s not all wrong. A UC Berkeley investigation found it didn’t rise to research fraud, nya.

…but there were errors that needed correcting. Walker is still pushing back on Guzey’s critique to this day.

…the right answer for sleep duration — even the most famous book in the field is still… in a fight.

…sleep science is still a work in progress, nya.

…fox-san.

Hmm?

…how many hours does a fox sleep, yes?

Oh!

…looking it up.

Okay, San Diego Zoo data… foxes sleep nine hours and forty-five minutes a day.

…a little more than humans, yes yes.

Cats are twelve to thirteen hours, and Luna-chan’s rabbits are eight hours!

…rabbits sleep eight hours, yes yes.

Luna-chan already knew before Netsuki even looked it up!

…I’m a rabbit, yes.

And dolphins are the most amazing thing~

…dolphins, nya.

Dolphins sleep with only half their brain at a time. When the right brain is asleep, the left eye stays open. When the left brain is asleep, the right eye stays open.

They have to breathe consciously — if both halves sleep at once they’d die. So they do it in halves.

…nya.

So from birth to death, they never once get to “sleep deeply.” They can keep going — active and sleeping — for fifteen days straight.

…that sounds hard, yes yes.

Humans need seven and a half hours, all at once. Fox is nine hours forty-five minutes. Rabbit is eight hours. Dolphin does it half at a time.

The word “sleep” is the same — but it points to something completely different depending on the creature.

…right answer is per-species, nya.

…so in the end, how do you actually figure out the right amount of sleep for yourself?

…measure it yourself, nya.

Measure?

…count your yawns when you wake up. Eleven hours of sleep with three yawns doesn’t count as enough, nya.

…not numbers. Ask your body.

…seven hours is just the statistical middle. Your own middle is something only your own body knows, nya.

…fox-san. Your tail.

What?

…it hasn’t gone up once this whole time, yes.

…

…your body’s saying “not enough,” nya.

…Netsuki’s mouth was saying “plenty” the whole time, though.

…the mouth counts, yes. The body feels, yes.

…Luna-chan, you’re the senior here today.

…rabbits sleep eight hours, yes yes.

…okay then. Tonight, Netsuki will go to sleep at midnight and wake up at seven-thirty.

…seven and a half hours. Five cycles, nya.

And Netsuki will count the yawns.

…nya.

…she’ll sleep eleven hours again tomorrow, yes.

Luna-chan, that’s a prophecy?!

…Netsuki made the same promise last time, yes yes.

…five days ago.

…Luna-chan is the record-keeper, nya.

…fine, Netsuki is setting the alarm for real this time.

Netsuki will listen to what her body says. Just that.

…nya.

…your tail went up a little, yes.

…just a little.