Greg had ni idea how long he'd been sleeping, had actually no idea at all that he was sleeping as he did so.
Eventually, he woke up, still feeling tired, but not as badly as before. He sighed, snuggled into the sheets and then realized he was lying on top of them and had, uncomfortably, fallen asleep in his clothes. He blinked, opening his eyes slowly and looked right at Sherlock, who was curled up in the middle of the bed. 
Greg froze for a second as he realized his situation.He sat up, groaning as his tired limbs moved. He leaned forward to see wether Sherlock was awake.
"Sorry,.." he yawned. "I didn't sleep a wink last night.. I didn't mean to.. do that here." he excused himself.