an Arduino UNO has 6 analog ports so you can even do 6.
YOu can combine these values into one value between 0-255 and use this to analogWRite() a PWM signal which is used to drive teh lightbulb.
But the latter you should ask on the electronic subforum: - how to drive a 220V bulb with PWM.
[mind you I don't know the formula of combining the 4/6 inputs to one output. Averaging does not seem like a good idea, as you want both the peaks and teh minima and duration and ...
If you find the formula please post