En ese intervalo de tiempo
 

How can I say en see intervalo de tiempo.
Context:
En ese intervalo the tiempo, se dedicó a descansar.
In that interval, he rested.????

'In that moment of time' would sound more natural, but 'in that interval of time' isn't out of the question.

In that moment of time, he rested.
In that space of time, he rested.
In that interval of time, he rested.
During that moment (of time), he rested.
During that space of time, he rested.
During that interval (of time), he rested.

He rested during ...
He rested in that ...
He rested for a space of time.
He rested for a moment.

He rested a spell. (spell = a space/moment of time)