Um, yep, sorta!
Have you ever seen a parrot fish or wrasse at night? The wedge into a crevice or down into the sand and surround themselves with a cocoon of slimy stuff, then rest there all night. when your lights go out in your tank, most of your fish will disappear into the rockwork and maintain a 'resting' position. some fish, such as cardinals, like the darkness and will become more active then, but the majority of fish do have a resting period.