NO its the light that stimulates the hen to lay in regular cycles.. but you have to be careful because if they get to much light it may turn into a pecking problem. You will read a lot that a red light is better to reduce pecking problems
and I have read on here before that if dont allow them to have a natural cycle it will shorten their laying life... meaning they will burn out faster
eta: when you say heat lamp... what colour is the bulb? red or white?