Hair material rendering darker in final render than in preview

As the title states, the material I’ve created for hair does render far darker than the preview. How come? The final render almost seem totally void of color or depth. Am I missing something? Any important settings that I may have forgotten to tick?

To clarify: I use Cycles for both preview and final render.

Check your outliner.

The most likely situation is that you have a light that is set to preview, but hidden in the render (or another object hidden in preview but rendering offscreen that is blocking the light.