Warriors say both, though most of the time they say 'sunrises'.
I thought they said moonhighs. Like, "Tigerheart and Dovepaw met a moonhigh ago."
Moon High is the afternoo,
So 'DovePaw and TigerClaw met the previous afternoon.
Sunrise is the warrior's talk for days. They have never said days in the books, only sunrises. Hope this helps! --Sandstar1051