Can you get wood lighter?

Having fitted bathroom with warm oak units. My present window facing/sill are well done and I am reluctant to change. The wood is mahogony, satin varnished. I'm useless in the decorating field and wonder if there is a product you can by that stains lighter to match more with the units and not ruin the wood? I don't want to just paint over in a colour or use stuff like Stain and Grain on good wood. Again perhaps trying to make mahogonay look like oak is just not done? Any info would be appreciated and hope I am not posting a stupid question that everyone but me knows the answer to. Thanks to all who reply.