Fig. 1: Distribution of time of blood draw for cases and controls during a typical working day (07:00–19:00).

SCZ cases (seen in blue) have recorded blood draws between 07:00 and 14:00 while controls (seen in green) have recorded blood draws between 07:00 and 19:00. This distribution suggests the potential bias that may occur when time of blood draw is not matched between cases and control.