This kind of thing is why I think cyclical changes of environmental conditions (temperature, light, etc) on short and long timescales was important for making t

This kind of thing is why I think cyclical changes of environmental conditions (temperature, light, etc) on short and long timescales was important for making the chemistry of early life work. There plausibly needs to be some way for enzymes and other processes to be switched on and off for various reasons, and if that just happened naturally through the day that would avoid the need for more sophisticated signalling/control machinery to have evolved spontaneously. It's easy to see how this could then evolve into the circadian rhythms that nearly all complex life on earth has as other processes were built into/around that basic behavior.