I have recently changed my bedroom light switch for a smart switch, enables me to turn the light on and off from anywhere in the house, laid in bed and even when I am in another town ( so it makes it look like someone is at home), all from an app on my phone. I can also ask "alexa" to turn it off an on too. Anyway, I had to change the wiring to the switch, Normally you have 3 wires in your light switch, live and switched live and earth. But with the switch I bought you need a 4th (neutral wire), to enable it to work. I would check the installation instructions with which ever switch you are looking at.