How to turn off phone access during nighttime hours?

My friend’s elderly father who is in assisted living keeps calling people during the late night. He is confused as to whether it is night or day. Is there a setting or app she could put on his phone that would prevent him fromcalling in the wee hours? If so, can it be set up one time to work over and over again automatically? Not having access to dialing out would not be a safety concern since he is in assisted living and has call buttons, and emergency pulls if he needs help.

There are many apps available that use parental controls on an iPhone or other iOS device. However, most of those apps simply track or restrict access to certain sites or things. Similiar to the parental controls on a Mac or PC. Have her do a Google search for those apps and then look them over to see if any meet her needs. If it was just one caller he's calling, it would be a simple matter to ignore or block the calls out. However, if he's calling other relatives and friends then it's not so simple.