If you flew through a red-eye period as a reserve, you're not able to be assigned a pairing assignment until 0800L the NEXT calendar day. In your case that would be a day off. However, this only applies if you operate at least 2hrs inside a red-eye period (0100-0500). So if you duty-out 0300L or later, you're covered. If you duty-out 0259L or earlier, it's less than 2hrs so this provision wouldn't apply.