Crisp, bright colours are your secret weapon when it comes to faking natural light in a windowless bathroom. Steer clear of the darker end of the colour spectrum; instead, paint your walls pale versions of warm colours, like buttercup yellow, pink and seaside shades of aqua blue. Select a colour two or three shades lighter for your trim and ceiling. As well as defining the space and offering visual contrast, this will draw the eye away from dark corners.
Lighting also plays a big part. Position warm lighting with a dimmer switch over the vanity and shower to make warm tones sparkle. Want to make an instant update? You can’t go wrong with a large mirror over your vanity - this will do wonders with helping to soften artificial light.