Quite a few of the shops and food places in the transit area stay open all night. There are several TV's on throughout. If the transit hotels are booked you can at least take a shower for about US$4.00 at the transit hotel. The check in counter opens at 4:45 (approximately). There are several benches and comfortable chairs around to get sleep in. If you don't leave the transit area you have no contact at all with immigration or customs.