Real adventurers who sleep through that sort of thing are dead. (Wizards have to be guarded by real adventurers.)
He won't particularly react or open his eyes, just yet; Esta will observe the course of events that happens by default, attempting to breathe slowly and what he guesses to be his sleeping breathing-pace.
(His, say, heart rate, may well pick up. Esta is not used to having to fool Dark Tapestry medical instrumentation.)