So I have looked, and looked for some RAW on sleeping in armor. Just to get me out of this pickle, and the only thing I see written about sleeping in armor comes from XGtE pg. 77-78. So we will use these rules for sleeping in armor. It has it that sleeping in light armor has no adverse effects, but medium and heavy armor have the following effects following a long rest:
- you only regain one quarter of your HD (minimum one die)
- if you have any levels in exhaustion the rest does not reduce your exhaustion level
This looks to me like it is ok to sleep in heavy armor just not ideal. Which sounds about right. Most nights you won't be worrying about exhaustion or HD and can sleep in the armor with no adverse effect on your character. Its those rare few that you'll have to slip it off and hope for no random encounter LOL