My literature review keeps growing to hundreds of papers, so how do I actually isolate a defensible research gap for my dissertation?

The secret to narrowing down your research gap isn't to keep reading more papers, but to stop treating your literature review as a summary and start treating it as a map of disagreements. You are likely drowning because you are focusing on what scholars agree on, whereas your dissertation needs to live in the friction where they disagree. If you find a study that seems to cover your potential gap, don't discard your idea immediately; instead, look at the limitations section of that paper. Often, researchers will admit that their findings are context-dependent or that their methodology excluded a specific demographic or variable. That is where your opportunity lies. You don't need to reinvent the wheel; you just need to find the specific corner of the field where the current consensus fails to account for a new perspective, a different cultural setting, or a shift in technological application. Imagine you are studying remote work productivity and you find a dozen papers claiming it increases output, but you notice they all focus exclusively on corporate software engineers. If you then find a study that touches on retail management but doesn't fully explore the psychological burnout of those specific workers, you have found your tension. You aren't just repeating the work; you are testing whether the established theory holds up in a different, more complex environment. To move forward, try creating a synthesis matrix where you plot authors against their core methodologies rather than their conclusions, as this will help you visualize where the gaps in their approaches actually exist. You should also sit down with your supervisor to present two or three of these specific contradictions rather than asking for a general direction, as this forces a more focused conversation. Finally, give yourself permission to stop searching for the perfect, untouched topic and start focusing on a nuanced extension of what already exists, because a defensible gap is often just a refinement of an existing debate. Your goal is to contribute a small, sturdy brick to the wall of knowledge rather than trying to build the entire structure from scratch.