Physical fitness and other individual factors relating to the shiftwork tolerance of women.

Maximal oxygen consumption (VO2max), muscle strength (MS) and physical activity were compared to age, shiftwork experience, morningness, personality traits and social factors intervening in the shiftwork tolerance of 128 women. The subjects were nurses and nursing aids working irregular shifts in a hospital. Neuroticism was the most powerful negative factor connected to higher fatigue and various symptoms of the subjects. High VO2max and good MS were, on the other hand, the most important positive factors connected to lower fatigue and musculoskeletal symptoms and better sleep quality of the subjects. In different shifts, fatigue, sleep length and quality were influenced most by morningness. It is concluded that physical fitness is an important individual factor explaining the variations of shiftwork tolerance in women.