Is a 15 Watt incandescent bulb in a lamp on a nightstand enough light to read by or would you recommend 25?

Not Steve but I would recommend 40 watts actually, if you’re wanting to read an actual book, and if the lamp has a shade that fully covers the bulb.

But then again, I don’t like dim lighting.

I like a lot of light to read by and would go with a 100 watt incandescent, myself, or a 15 watt LED.

Does the lamp have a 3 way socket? A 40-60-100 three way bulb might work well if it does.

As SK said, a lot depends on the shade. Some are fairly opaque and direct light downwards. Others, especially lighter color shades, disperse the light outward. You might have to experiment and see what works for you. I like dim light in general, but these aging eyes need a lot more light to see at night; I don't think the 15W or the 25W would be enough for me. 40W would be the minimum, more likely 60W.

A dedicated book light is kind of nice, too. I use one of these:

https://www.amazon.com/Vekkia-...ls%2C107&sr=1-4&th=1

It has three light levels and lasts a pretty long time between charges.