The Impact of Long Night Shifts on Nurses’ Ability to Recognize Facial Expressions

Abstract

To clarify the impact of long night shifts on nurses’ ability to recognize facial expressions, we recruited 28 healthy female nurses working double shifts and measured their ability to recognize facial expressions before and after long night shifts. A “facial expression discrimination ability program” was used to measure the nurses’ recognition of six basic emotions: “surprise,” “fear,” “hatred,” “anger,” “sorrow,” and “joy.” The facial expression discrimination thresholds of these emotions were identified and the nurses’ levels of stress (salivary amylase activity level) and fatigue (subjective symptoms of fatigue) were also measured. The results showed that the easiest facial expression to recognize both before and after night shifts was “joy,” followed by “surprise,” “anger,” “sorrow,” “hatred,” and “fear,” in that order. However, after night shifts, the nurses had significantly more ease recognizing “anger” and “hatred.” This was likely because sleep deprivation resulting from long night shifts is linked to hyperactivity of the amygdala in the brain when a facial expression is observed, which heightens the emotional response to this facial expression. This study confirmed that “joy” is the easiest expression to recognize and is not affected by night shift-related stress or fatigue.