Thats a real problem and the only way to fix is using a real point light (thats is a bulb light). Dont put it inside the real bulb object and set it to ignore the bulb model, so you dont get a strange shadow of the bulb in the roof.

Set the bulb to glow material and add some Aura effect to this object. This aura will create the glow in it.

Dont use shadows at 100% this will create a very dark shadow, unless you will use Indirect Light to render, that will minimize this effect, the good point is about 65 - 85 percent.

Remember that turning on GI will wash your scene and colors will get more light.

Also use cone lights intead distant ones, its more faster to render and get better results and control.

Dont forget to use soft shadows to kill the hard edges of the shadows (men this looks like a title for Batmam movies...)

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