Is running an app all night harmful to the iPhone? I use some apps that listen to my sleep, such as SnoreLab, to give me details on my sleep quality. These apps need to run all night, the iPhone being unlocked (but the screen is black because it faces the table). The iPhone is also charging all night.

I was wondering if using this kind of apps, running all night, is harmful in any way to the iPhone.
It could possibly be harmful if the phone overheats, though I spent several months with an older iPhone between my pillow and the bed, plugged in and charging, and never had any problems.

Other than that, no.