You can wear a messy diaper all day or all night if you want too.
I would recommend putting some diaper rash cream on your diaper area and then you can stay in the messy diaper all night and even all day.
I poop a diaper during the evening and then I wear it all through the night and then sometimes wear it for another few hours or until 12:00 PM before showering and changing the diaper.
I walk around in the messy diaper for as long as I can and if I had just pooped the diaper and not wet it yet then I keep the messy diaper on until I at least wet it a few times.
A wet and messy diaper feels great to sleep in and walk around in as well.