I don't know if they're all infrared or what (honestly don't know what mine is) but it doesn't scare them. They may wake up and eyeball it, but settle back down without issue.
You have to check each camera to see what the specifications are. I use mine as live feed as I don't have an account to save video. Others may save video to your computer, cloud storage, or to a flash drive. Other things to consider: power source (battery, wired in, solar?) and internet/WiFi connection, if you want to watch off a phone or computer.