What is the test for discharging a juror from a jury for falling asleep during trial?

The trial court may discharge a juror who "becomes ill, or upon other good cause shown to the court is found to be unable to perform his or her duty . . . ." ( 1089.) While extreme inattentiveness due to sleeping may constitute good cause to discharge a juror, " 'courts have exhibited an understandable reluctance to overturn jury verdicts on the ground of inattentiveness during trial. . . . Perhaps recognizing the soporific effect of many trials when viewed from a layman's perspective, these cases uniformly decline to order a new trial in the absence of convincing proof that the jurors were actually asleep during material portions of the trial. [Citations.]' [Citation.]" (People v. Bradford (1997) 15 Cal.4th 1229, 1349 (Bradford).) "A juror must not be discharged for sleeping unless there is convincing proof the juror actually slept during trial. [Citations.]" (People v. Bowers (2001) 87 Cal.App.4th 722, 731.)