Dawn didn't exist underground, but sleep and wake cycles marked the passage of time as effectively as the absent sun.
And of course, the "digital" time in the book too... Elio didn't understand why the god called it that in his general notes, or what it meant, but having it in the book was very useful for measuring time.
The tunnel, illuminated by the soft glow of cores and builders' summons, was already buzzing with morning activity.
Zara remained apart from Elio, her tense posture revealing her disagreement with the plan.
She had argued fervently to participate in the daily challenge, but Taron had been inflexible: they needed her strength outside, ready to defend the tunnel if something went wrong.
"If the Artromus detects something..." Taron had argued, "you're the only one besides Elio with enough power to at least buy time."