"Honey," Night Light said, as he trotted into the living room with not one but two ponies on his tail, "we're going to need another chair."

Twilight Velvet looked up from where she was adjusting the lectern in front of the drapes over the picture window, and did a double-take. "Princess? What are you doing here?"

"Mom," the curtains stage-whispered, "I [i]invited[/i] Cadance."

"I think she means the [i]other[/i] princess, little ladybug," Cadance said.

The curtains gasped and rustled, and a wide-eyed purple head popped out. "Princess Celestia?!" Twilight squeaked.

Celestia stepped forward past Night Light and Shining Armor, smiling at the little filly. "I hope you'll forgive me showing up without an invitation—but when I overheard from one of my most promising young guardstallions that my faithful student is giving a presentation on an independent research project, I knew I couldn't miss it."

"Mom mom mom!" Twilight said, dashing out from the curtains. "If we're setting up a new chair I'll have to redo all the seating calculations—"

"It's alright, Twilight," Celestia interjected with an impish smile. "I'll take Cadance's seat. I'm sure that she and Lieutenant Armor can find a way to both fit on the sofa chair."

Cadance's eyes lit up and her wingtips quivered. Shining's blush deepened.

He was finally coaxed onto the sofa, where Cadance sprawled across him with a goofy grin, and Night Light and Twilight Velvet exchanged knowing smiles before taking their own seats and lowering the room lights.

The picture-window curtains rustled, and Twilight stepped out, clambering up onto a stool behind the lectern, her eyes barely visible over its top edge. She cleared her throat and tapped a glowing stack of index cards to the surface. "On Filly Bedtime Optimization: Results Of A Longitudinal Study Of Monophasic Som. Somnel." She squinted.

"Somnolence," Velvet prompted.

"I know, mom. I misspelled it on the card." Twilight paused to correct her notes. "Slide."

Night Light clicked the button on the projector. A hoof-drawn graph sprang onto the screen.

"As you can see," Twilight said, "I tracked my bedtime over the course of a two-month study, plotting it against several objective and subjective factors. Slide." New lines sprang onto the graph. "You can see my test grades here—" she pointed to a flat line along the top—"along with self-reported productivity levels, and survey-collected data on my grumpiness at breakfast." Twilight switched index cards. "Footnote one. Velvet, comma, Twilight. 992 CE. Anyway—slide—the data show strong, uniform correlations. And as you can see, my proposal easily exceeds the minimum CAS bed rest recommendations. Plus it would result in a 60% decrease in artificial lighting usage—"

"Hang on," Shining Armor said, squinting over Cadance's back. "You're saying Mom and Dad should send you to bed at [i]seven PM[/i]?!"

Cadance giggled, brushing a wingtip to his neck. "I don't know, Shiny. Maybe it deserves some experimental confirmation while I'm sitting for her tonight…"

[hr]

"Seven on the nose," Cadance said over the soft midnight chirrups of crickets, as Shining Armor hurriedly smoothed down his clothing and scooted toward the far end of the couch. "Not a peep from her room since."

"That's probably because there was a Royal Guard keeping the peace here," Night Light said. "You know, we could probably get Celestia to transfer him…"

[i]"Dad!"[/i]

"Stop teasing Shining, dear," Twilight Velvet said, slipping off her white lab coat, "and come check on your daughter with me."

Night Light raised an eyebrow. "I know Twiley, honey. She wouldn't have gone to all that effort if she didn't genuinely want to be in bed by seven."

Velvet caught his collar in her horngrip and dragged him upstairs. "You know Twiley, dear, but you don't know [i]science[/i]."

When they pushed open Twilight's door, the lights were out, but the blankets on her bed had a giant glowing lump in the center, inside which the silhouette of a filly flipped the page of a book.

Velvet cleared her throat. The filly's hornlight winked out, and after a moment's frantic scrambling noises, they found her with her eyes closed on top of a stack of library books.

"Nice try, sweetie," Velvet said, sitting on a corner of the bed. "But I noticed something interesting when I checked your sources. It turns out that 'bed rest', as clinically defined, is not actually the same thing as 'sleep'. And you never addressed [i]sleep[/i] hours."

Twilight opened one eye, then guiltily sat up. 

"Does this mean," she said, "my study's not passing peer review?"