Sorry for the late reply, but frankly, for six hours, I’d just go to one of the pay lounges and take a nap there. By the time you’ve checked into a hotel and settled in, it’ll be time to get up again.
Lounges in the UAE are the best on the planet - IIRC, one of the Marhaba lounges at DXB is absolutely huge and has a quiet area with couches. Look on sleepinginairports.net.
There are a couple of sleep-pod places within the terminals (connect to the free WiFi to navigate around!) but I can’t say I’ve ever tried them. They’re pretty expensive.