I've seen so many interpretations of that final chapter. I think the 'awakening' is literal—the protagonist, Leo, really does wake up in a hospital bed after a long coma, and everything in the 'Dream' world was his brain's way of processing the trauma of the car accident. But the 'real meaning' that hit me hardest was about letting go. The Nightmare wasn't the monster he fought; it was his own refusal to accept his changed reality. By choosing to wake up, he wasn't defeating the fantasy, he was finally choosing the flawed, painful, real world over a perfect, self-made prison. The book's last line about the sunlight feeling 'strange and new' gets me every time—it's not a triumphant return, it's a fragile, terrifying fresh start.
Some readers argue it's all a metaphor for depression, and the Nightmare is just his brain chemistry. I don't fully buy that, but the idea that the 'happy ending' is simply the capacity to face another day, with all its mundane struggles, feels brutally honest. The meaning is in the quiet, not the grand battle.