Clara hadn't told him because she rarely thought about it – it rarely happened and it hadn't happened in an incredibly long time – but she occasionally got out of bed, in the dead of night, and roamed. In her sleep. Usually it wasn't further than her door, maybe a step or two outside and she'd go back to find her bed, dropping into it to curl back underneath the sheets to slip back into whatever dream she'd been having.
Sometimes she moved into her closet, to shop away in an imaginary store.
Sometimes she searched the fridge because she was at the grocers.
Sometimes she woke on the couch, some dream of a film fading from memory.
And sometimes she woke on the floor, having forgotten where she'd been off to in the first place.
It didn't seem like something she should mention to him because she was sure she'd never really spend nights aboard the Tardis, the tiniest bit for that reason, and when she finally did, it slipped her mind. She was exhausted on those nights after a long day saving some planet or person or peoples. Clara would trail into the Tardis after him and he would caress her cheek and tell her lovingly, "Why don't you get some rest, Clara," and she'd reply, "Not tired, Doctor," and he would chuckle.
The Doctor always chuckled.
And then he'd sigh, "Humans."
His fingers slowly slipping from her skin as she moved away, Clara would bow her head and smile to herself as she went to find her room, a room she'd continually told him was unnecessary, but a room she appreciated none the less and she'd fall into the enormous bed he'd constructed for her. To rest her eyes, she'd always assure herself. She'd snuggle into the mass of pillows and thick fluffy sheets like a smooth red wine soothing her body and, inevitably, she'd drift to sleep.
Clara hadn't told him because it hadn't seemed a problem. She'd slept so soundly and so deeply that she imagined her limbs were simply too tired to pick themselves back up to walk about the Tardis while he tinkered on his ship. Clara hadn't told him because she didn't think it would be an issue and so when she opened her eyes slowly and found herself looking into a bare chest over which her fingers fanned out, she was startled.
She was on her side, burrowed into a bed she knew wasn't her own, and her eyes went wide as she took in the starry pattern on the navy blue sheets that were half over head and then back at the pale body in front of her, one her fingers curled away from before she raised her eyes to the Doctor's confused face, blinking back down at her. Clara swallowed roughly and she told him lightly, "I'm so sorry."
Looking towards the bedroom's entrance, the Doctor asserted curiously, "You sleepwalk."
"I am so sorry," Clara repeated, eyes closing tightly.
"You walked, in your sleep, into my bedroom," the Doctor's brow came together, "How did you even get into my bedroom, it's got a psych lock…"
Lifting herself up slightly, Clara muttered, "I am so sorry."
She began to move away, but he lightly touched her arm and when she turned, he was smiling, shaking his head, and nodding to the bed, "Stay."
"But it's your bed," Clara gestured.
"Yes," he nodded, "Stay."
"But it's your bedroom," Clara hissed lightly.
"Yes," he laughed, "Stay."
"But you said yourself; shouldn't even have been able to get in."
Head toggling slightly as he dropped back to the pillow, the Doctor allowed, "And obviously something in your psyche was important enough that the Tardis decided to override my commands and let you in."
Clara slowly nestled back against the mattress and she watched him swing his arms up, resting his head against his palms as he smirked up at the ceiling, "I used to sleep walk, when I was younger. My mum told me I had too much on my mind, said I had so many thoughts knackering about in my head…"
He turned and she went silent as he nodded, then told her, "Are you alright, Clara?"
Frowning, she replied, "The threat count on these sheets must be insane – are they space woven?"
With a small laugh, he shook his head, "That's not what I meant," then he shrugged, "Sleepwalking is more common in childhood; sleepwalking as an adult could mean a number of things and since I've scanned you for ailments and you've come off clean, I can only assume you're tired, or stressed." Looking back at her, he asked gently, "Are you alright, Clara?"
Shrugging, she looked away from his curious stare before telling him, "Suppose tired, we were up for days it seemed, back on that planet – no sun, how do you know how many days have passed? Could have been a single day, could have been a couple and we'd have never known."
He smiled and shifted, turning onto his side and curling his hands just in front of him to admit, "It was thirty two hours and fifty three minutes," and before she could ask, he offered, "I was keeping track on the Sonic."
"It's a timer now?" Clara teased.
"Could be, it is multi-functional, you know," he mumbled in response.
"Except it still doesn't do wood," she whispered.
He smirked and waited for her eyes to meet his again and when they did, he reached out for her own hands, lying atop one another just underneath her chin and he pulled one free to kiss her knuckles, "Are you sure you're alright, Clara?"
"Ah," she breathed, "Don't worry about me, Doctor."
Sighing, he held her hand within his and looked her over as she blinked slowly, the exhaustion starting to re-settle into her face as she relaxed. "How could I not," he admitted. "Sleep," he ordered.
He watched her nod, giving him the smallest of smiles before she closed her eyes, grip on his hand tightening for a few moments until it went limp, her body succumbing to the rest he knew she needed. Rest he knew he needed. Shifting closer to her, he swept her hair behind her ear and whispered gently, "Clara, you're someplace safe, you're protected and there's no need to worry – not about where you are or what's in the stars," he smiled, kissing her knuckles again to add, "or me."
Clara took a long breath and on her exhale, she whispered, "How could I not," and the Doctor shifted forward, pressing a warm kiss to her forehead before settling himself in at her side to watch her until he was certain she was sleeping soundly and it was only then he allowed his own eyes to flutter shut.