Several definitions of stress have been introduced in the liter- ature yielding different discrete or continuous descriptions of this variable. In this study, due to the data available in the VI NSWC, we considered the symptomatic definition used in INSHT (1999). In the short term, stress can manifest by symptoms of physiologi- cal, behavioral, or psychological nature. The twelve stress-related symptoms asked for in the VI NSWC included: trouble sleeping or sleeping poorly, constant feeling of fatigue, headaches, dizziness, trouble concentrating or staying focused, trouble remembering things or easily forgetting them, feeling tense or irritable, feeling emotionally exhausted, always thinking about problems at work, eating disorders, eye problems, and lack of energy