She had it figured out.
No one did the fetal position at night time like Carol. She'd curl up tight, covering herself with whatever was laying around. A jacket or an unzipped backpack - a blanket if she was lucky - and she'd cover just enough of her face so that her breath could warm whatever was underneath.
And when it came time for Daryl to pass of his watch shift to T-Dog and take his place beside her for the night, she'd uncurl herself and fit her front snugly against his back, and he'd fall asleep to her soothing warmth.