- Mental behavior disorders Most crew members have psychological changes due to causes such as anxiety about disaster, feelings of loneliness, worries about family, economy... monotonous and boring work; shift working mode; lack of 21 recreational activities while having ample spare time; Abnormal micro - social environment on board (homosexual)... These are favorable causes of occupational diseases which arise with high incidence and greatly affect the health of seafarers, reducing their age.