The 46-year-old actress and husband Andrew Upton - who also have three biological children Dashiell, 13, Roman, 10, and seven-year-old Ignatius - adopted Edith Vivian Patricia last year, reported Femalefirst.
"I feel a bit sleep-deprived," she said.
However, Blanchett, who is preparing to tread the boards in an upcoming production of "The Present", said there are some benefits.
"Although sometimes, it can be good to be a bit tired in a rehearsal room because your guard is down.