I thought this was obvious because she’s a goddess reincarnated. They sort of explain this in Skyward Sword.
This comment made me shift my perspective on Zelda, no joke. I’ve always been annoyed (and still am) that there isn’t a game where you actually play as Zelda, but this does a nice job of showing WHY she’s always getting attacked first, and why Ganon/Demise are always defeated not long after Link reunites with her: she’s the true source of power to defeat them.
Ever since then, her sleep's become unusually light.
She confirms the rustle of every blade of grass, every sound on the pavement, one by one.
She's scared.
Scared of her own negligence, of allowing another crisis to befall a comrade.
She's long since been unable to sleep soundly, even aboard Rhodes Island.
And the reward she most hopes for at the end of a hard day's work has changed too, from a neverending dream, to a simple breather on a bench.
This, for her and her alone,
is the price of maturity.