He should be well-rested for Sunday's game against the Miami Dolphins. Head coach Rex Ryan has brought in sleep specialists to help the team stay rested during practices and during games. Rex commented (via ESPN):
We've had sleep people come in, talking about how important sleep is, how important it is to get eight hours of it. We bring in these specialists for a reason... If we can gain a little advantage, then we're going to look for it.
Whether or not sleep is a factor, conditioning will likely matter in Miami on Sunday. The Dolphins have a strong home-field advantage in Septembers due to the intense heat in southern Florida.
The Jets will need to be healthy, rested, energized and everything else so that they can go to 2-1. After a winnable game against the Dolphins, they will face the San Francisco 49ers and the Houston Texans.