That made him squint a little. He prodded at the mattress, considering the way it squished down and slowly poofed back up into place. "Memory foam. I don't understand," he murmured, almost more to himself than to Dean. "The bed remembers you?"
Castiel liked being able to be this close to Dean. He could see his freckles, and the lines starting to trace out Dean's smiles and frowns on his skin. He shifted a little closer to Dean so that the pillow didn't block his view so much. If he reached across the space left between them, Cas could touch him, could maybe soak in a little more of Dean's warmth. He kept still.
"I slept once, during the apocalypse. When I was cut off from Heaven," he mused. He paused to think about it for a moment, his gaze wandering and one corner of his mouth twisting upwards. "Hmm. I have not attempted to do so on purpose, but... I imagine I could. It is a bodily function like any other; I can suppress or induce it as I choose." He blinked and went back to staring at Dean. "Is it desirable, when not needed? It seems... time-consuming."