In People v. Espinosa (1992) 3 Cal.4th 806, the defendant asserted error based on the failure of the trial court to conduct an inquiry in response to defense counsel's statement "that a certain juror 'appeared' to be asleep." (Id. at p. 821.) The trial court indicated that it had not observed this. (Ibid.) The high court rejected the challenge, reasoning, "Once a trial court is put on notice that good cause to discharge a juror may exist, it is the court's duty 'to make whatever inquiry is reasonably necessary' to determine whether the juror should be discharged. We have recently explained, however, that the mere suggestion of juror 'inattention' does not require a formal hearing disrupting the trial of a case. Here, defense counsel stated that, after watching the juror in question for 'several seconds,' he thought the juror 'appeared' to be asleep. Counsel's mere speculation that the juror might have been sleeping, which was insufficient to apprise the trial court that good cause to discharge might exist, did not obligate the court to conduct any further inquiry." (Ibid.)