Performance of the indirect antiglobulin test does not show a circadian rhythm

Performance of the indirect antiglobulin test by workers in a blood bank was examined for signs of a rhythmical relationship between the time of day and the frequency of error. All participants were experienced in blood group serology and completed sets of 12 antiglobulin tests at 4-hour intervals over a 24-hour period. Ten of the original 17 participants repeated the experiment after an interval of 7 months. About 50 percent of participants made more errors in the daytime or the nighttime in each experiment; however, these groups were unstable and contained different individuals in each experiment. Significant (p less than or equal to 0.05) time-related cosinor rhythms could be demonstrated for four individuals in one experiment, but this finding was not reproduced in a second experiment. There was no indication that the amount of sleep deprivation which occurred had a significant influence on the investigation, and the individual frequencies of error at 0800 hours appeared to be a stable individual characteristic. The results highlight the importance of examining workplace-related performance as an individual rather than a group phenomenon.