"Four hours... yeah." Steve wanted to sleep so much longer than four hours, but it sounded like a reasonable compromise. (In truth, he'd probably sleep for at least eight, if Sam didn't wake him up.) The hand on his back felt soothing, calming, and it was getting hard to keep his eyes open, which was probably the point. He reached over, giving Sam's knee a gentle squeeze, before he started to move, trying to lie down on his good side, so that his bad side wouldn't take any of his weight. He let out a breath - and he didn't so much fall asleep as pass out, within the span of a few seconds.