Lol, you said the same thing as me but in reverse
Ok, ok, there's this misconception that somehow the Oxygen bubbles increase O2 levels. They increase the O2 levels by the surface agitation they create. Not because you are fizzing gas in the water. O2, as far as I know, is less soluble in water than CO2.
You may run the airstone at night, if you want to, but that will not save your fish during the day.