Studies on fatigue of night duty workers at a newspaper office.

Fatigue of night duty workers in different divisions of a newspaper office was investigated by physiological methods such as the Blinker, Flicker and grip methods. The relationship between fatigue and hematological parameters such as hemoglobin (Hb), the hematocrit (Ht), serum-free amino acid levels, and indices of liver function such as the GOT and GPT levels were also examined. The composing and press room workers mainly complained of the subjective symptom of muscle fatigue, while workers in the photo-engraving and editorial departments mainly complained of mental fatigue. The overall rate of fatigue in the newspaper office was about 38.1%, but varied from one division to another, being especially high in the photo-engraving and editorial departments. The subjects with fatigue had low levels of serum GOT and GPT and high levels of serum-gluconeogenic amino acids, such as aspartic acid, glutamic acid, prolin, glycine, and alanine. These altered levels of serum-free amino acids and GOT and GPT seemed to be due to increased secretion of adrenal corticoid hormone caused by the stress of fatigue.