budgie red light how long?

My male budgie has been fluffed up and calm since today.

Now I assume that it is he who is producing slightly softer stools.

Since he came to me, I don't know how old he is.

He only gets grains from the grain store (no fruit, vegetables, or greens that could change his stool).

he eats and drinks normally.

The housing and feeding conditions have been the same for two years.

Now I've set up a red light lamp at an acute angle to the perches, giving the wellies a chance to escape.

How long should I leave the red light on?

And NO, I don't have a veterinarian with expertise in birds within a 100 km radius. And I'm not going to put the bird through the stress of catching it (it's not hand-tame!) and transporting it, etc. Please no comments on that. My question is about the red light!