When Robert Langdon awakes from his nightmare full of Dante’s allusions, he does not remember anything that has happened for the last three days. Robert does not know where he is, what happened to him, or even what time it is showing how he is both lost literally and lost in time. Brown introduces Robert Langdon as one who is lost from his path.
Both of the protagonists all began their journey lost and confused. Because Dante writes that he was “so drugged and loose with sleep”, Brown have Robert Langdon wake up and be drugged to begin his travel as well.