I used to be opposed to napping during the day. If I did I usually couldn't get back to sleep at night, or would be restless and wake up feeling hungover.
Being in a household where both of us are shift/on-call workers, I am now embracing the mid-day nap.
There are many nights where one, or both of us are up on calls, sometimes lasting hours, in the middle of the night. Needless to say, this really F*&#s with your sleep. The good news is, banking sleep is totally a legit thing that we should all be doing, especially in those instances where you didn't get all that much the night before.