Effects of working permanent night shifts and two shifts on cognitive and psychomotor performance.

Objectives: The study aimed to clarify whether cognitive and psychomotor performance, which are important for occupational and traffic safety, are impaired by working permanent night shifts (NSs) compared with early-late two shifts (TSs) and whether age and chronobiological type influences the relationship between shift and performance.

Methods: The study included 44 male automobile workers, 20 working TSs and 24 working NSs. Chronobiological type was determined by questionnaire (D-MEQ).