Why We Sleep

Mira did not want to go to bed.

She had already brushed her teeth. She had already put on her pajamas — the ones with the little rockets on them. She had already listened to two stories, gotten a drink of water, and checked under the bed for anything suspicious.

But she still did not want to go to bed.

"I'm not even tired," Mira said, crossing her arms. She sat straight up against her pillow like a board.

Her mom kissed her forehead. "Goodnight, sweetheart."

"But what does sleep even do?" Mira asked. "I just lie here. With my eyes closed. Doing nothing. It's the most nothing thing in the whole world."

Her mom smiled in that way that meant she knew something. "Oh, Mira. You have no idea how busy you're about to be."

Then she turned off the light.

Mira huffed. She stared at the ceiling. She counted the glow-in-the-dark stars she'd stuck up there — fourteen and a half, because one had broken.

And then, without meaning to at all, she fell asleep.

The first thing Mira heard was a tiny bell.

Ding!

She opened her eyes and found herself standing in the middle of — well, it looked like the inside of a giant library, except nothing was quite right. The shelves were curved and pink and slightly glowing, like the inside of a seashell. Instead of books, the shelves were filled with little glass jars, and inside each jar was something shimmering.

"Excuse me! Coming through! Watch your elbows!"

A small creature zipped past Mira on a scooter. It was about the size of a squirrel, round and blue, wearing a tiny hard hat and a vest that said NIGHT SHIFT in sparkly letters.

"Wait!" Mira called. "Where am I?"

The creature skidded to a stop and looked up at her with enormous golden eyes. "Where are you? WHERE ARE YOU?" It adjusted its hard hat. "You're inside your brain, obviously. I'm Fiz. I work here. And you are extremely in the way."

"My brain?"

"Yes! And we've got a LOT of work to do tonight, so if you could just —" Fiz grabbed a glass jar from a passing conveyor belt. Inside the jar, Mira could see something glowing and moving, like a tiny movie. She leaned closer.

It was her. In the jar, a tiny version of Mira was learning to do a cartwheel at recess. She could see the grass, the blue sky, her friend Kenji clapping.

"What is that?" she whispered.

Fiz held up the jar proudly. "This is a memory from today. A good one, too — see how bright it is? My job is to figure out where it goes." Fiz zoomed up a long, spiraling ramp to a high shelf labeled THINGS I CAN DO and carefully placed the jar between one that showed Mira tying her shoes and another of her riding a bike.

"You're organizing my memories?" Mira asked.

"Every single night!" Fiz slid back down the ramp. "You think remembering stuff just happens? HA! Do you know how many things you saw and heard and thought today? Thousands! THOUSANDS, Mira! And most of it is junk — like that time you read the same cereal box three times at breakfast."

"I like reading the cereal box."

"Sure you do. But do you need to remember it forever?" Fiz tossed a dull gray jar into a bin marked RECYCLING. "We keep the important stuff. We file it. We connect it to other memories so you can find it later. That spelling test you studied for? Right now, my team is moving all those words into long-term storage."

Mira looked around and saw dozens of other little blue creatures, all in hard hats, all bustling around the shelves. Some were carrying jars. Some were building new shelves. Two of them were connecting jars together with little golden threads.

"What are those threads?" Mira asked.

"Connections!" Fiz beamed. "See this one? This jar is the memory of your grandma making pancakes. And THIS jar is the memory of the word delicious from vocabulary last week. We connect them together so that next time someone says delicious, you might think of Grandma's pancakes." Fiz wiggled its eyebrows. "Pretty cool, right?"

It was pretty cool.

"Okay," Mira said. "But that's just my brain. What about the rest of me? My arms and legs don't need to sort memories."

Fiz stared at her. Then it started laughing so hard it fell off its scooter.

"Oh, you think your brain is the only one working tonight? Follow me."

Fiz led Mira through a round doorway, and suddenly they were somewhere completely different. It looked like a construction site — but soft, warm, and glowing red. Everywhere Mira looked, teams of little creatures (these ones were green) were building things.

"Welcome to the Body Department!" announced a green creature with a clipboard. Her name tag said Captain Voss. "We've been expecting you. Well, not you you. We've been expecting your sleep. Same thing."

"What are you building?" Mira asked.

"Right now? Muscle." Captain Voss pointed to where a crew was carefully layering tiny fibers together like threads in a rope. "You did a lot of running today. Your legs got tiny little tears in them — totally normal — and we're patching them up. By morning, they'll actually be a little bit stronger than yesterday."

"Stronger? From sleeping?"

"From sleeping! Where do you think strength comes from, a store?" Captain Voss chuckled and checked her clipboard. "We've also got a team working on that scrape on your left knee. Regrowing skin, fighting off germs — the usual."

Mira looked down at her knee. It had been bothering her today.

"And over there —" Captain Voss pointed to a quieter section where green creatures were gently tending to something that looked like a garden of tiny glowing trees. "That's your immune system. We're training it tonight. Giving the cells practice so they recognize bad germs faster next time. Think of it like a rehearsal."

"My body is rehearsing?"

"Every. Single. Night." Captain Voss leaned in. "Here's the thing, kid. During the day, your body is busy doing what YOU want — running, jumping, eating, talking. It barely has time to fix anything. But at night, when you're quiet and still? That's when we get to work. That's when the real stuff happens."

Mira watched the tiny crews hammering and building and mending. She thought about how she'd always imagined sleep as a big blank nothing.

"I had no idea all this was going on," she said softly.

"Most people don't!" Fiz reappeared on its scooter, eating a tiny sandwich. "They think they're doing nothing. Meanwhile, we're running the biggest operation in the whole body. Memory filing, muscle repair, bone growing, germ fighting, emotion sorting —"

"Emotion sorting?"

Fiz suddenly looked sheepish. "Oh. Yeah. That's... the other department."

"Can I see it?"

Fiz hesitated. Then it sighed. "Fine. But it's a little... mushier in there."

The Feelings Room was warm and dim, like being wrapped in a blanket. Soft golden creatures — smaller than Fiz, rounder, quieter — were gently sorting through what looked like colored clouds.

A dark blue cloud drifted by. Mira recognized the feeling inside it immediately: that moment at lunch when Priya didn't save her a seat.

A golden creature caught the cloud and held it softly, and slowly, slowly, the dark blue faded to a lighter shade. Not gone. But gentler.

"We don't erase the hard feelings," the creature said quietly. "We just help them settle. So tomorrow, they don't feel so big."

Mira watched the creature place the lighter cloud carefully on a shelf. Right next to it was a bright yellow cloud — the memory of Priya sharing her markers during art.

"Oh," Mira said. "So I can remember both."

The creature nodded.

Mira stood there for a moment, looking at those two clouds side by side — the blue one and the yellow one. She was glad neither one had been thrown away.

A bell rang somewhere far away. Fiz tugged on Mira's sleeve.

"That's the morning bell. Time for us to clock out. Time for YOU to wake up."

Mira looked around at all the bustling workers — the blue ones, the green ones, the golden ones — all waving at her, already tidying up for the day.

"Thank you," Mira said. "I didn't know you were all in there."

Fiz grinned. "We're in there every night. Long as you show up."

Mira opened her eyes. Real eyes, this time. Sunshine. Her bedroom ceiling. Fourteen and a half glow-in-the-dark stars.

She stretched her arms and noticed something.

Her knee didn't hurt anymore.

She could remember every single spelling word.

And that thing with Priya? It still felt a little sad. But it didn't feel so heavy.

Mira smiled, hopped out of bed, and went downstairs for breakfast.

That night, when her mom said it was bedtime, Mira grabbed her rocket pajamas and climbed right in.

"Goodnight, Fiz," she whispered.

And somewhere deep inside, a tiny bell went ding.