No, you shouldn’t! Wearing a harness for extended periods of time may cause your dog to develop armpit sores due to sustained pressure. Additionally, it shouldn’t be worn to sleep as it can cause discomfort when he’s lying on his side.
Moreover, if your pup tends to move about during his sleep, the harness may get caught on his cage or other objects, causing him to choke. Hence, you should only put your dog in a harness when he needs it.