they don't sleep in caves, but u definitely should have some hiding spaces they are very active fish though so they want use them much, males are much more active then females , females tend to hide alot more
In my experience both sexes are equally as active (in fact my females are more active).
Anyway they'll sleep where ever. My boy sleeps in his plants, next to the filter, on the sand (even lying on the sand). My girls sleep everywhere as well; they just need somewhere to rest.
my girls sleep in caves and other ornaments that contain holes they fit in
then my male would sleep in a cave but i dont have any in his tank just a truck load of plants lol but at the top at the back he sleeps there as the light dsnt reach there to well so he like it
Mine likes to sleep either under the wood, or hidden under the anubias on top of the wood.
This Betta keeping isn't easy, I keep thinking he's dead, as I 've never had a fish that actually lays down to sleep, it's quite perturbing!