In that fatigue and distress have been separately shown to be associated with medical errors, Colin P. West, from Mayo Clinic (Minnesota, USA), and colleagues studied the interplay between these and other performance factors.   The team collected data on 380 categorical and preliminary internal medicine residents at Mayo Clinic, who began their training from 2003 to 2008 and were surveyed quarterly through early 2009 to identify self-assessment of medical errors, self-assessment of overall quality of life, fatigue, work burnout, depression, and sleepiness.  The researchers found that residents who reported at least one medical error were prone to: lower self-rated quality of life; higher levels of depersonalization; increased feelings of emotional exhaustion; and lower sense of individual accomplishment. Further, of those who reported an error, 68.7% screened positive for depression at some point during the study, compared with 43.6% of those who did not report any errors.  The team concludes that: “Among internal medicine residents, higher levels of fatigue and distress are independently associated with self-perceived medical errors.”