Background Stress and fatigue are psychosocial risks for nursing workers and salivary cortisol is considered the most promising marker to assess the neurobiological response to stress. It plays an important role in research in occupational health because its high levels and the activation of the sympathetic system can lead to negative effects on health.

Aims To determine whether salivary cortisol may be a potentially useful biomarker of stress and fatigue among nurses and its relationship with night shift work.

Methods An integrative literature review was performed in the databases MEDLINE, WOS, SCOPUS, LILACS e SciELO using the terms “Cortisol OR Stress Or Fatigue AND Nursing” in Portuguese and English. The level of evidence of the studies was determined using the Oxford Centre for Evidence-Based Medicine. The inclusion criteria were defined as follows: studies published between 2006 and 2015; in Portuguese, English and Spanish; with abstract available in the selected databases.

Results Of the 987 articles captured by the search terms, 45 articles met the inclusion criteria. Papers evaluating the interrelationship between salivary cortisol levels, stress and fatigue among workers showed low evidence level. According to the Oxford criteria, seven articles were classified as level 6 while one study was level 4.

Conclusion There were significant relationship between night shift work, stress and fatigue among nursing workers; however, there was no definitive evidence regarding the salivary cortisol and these variables. The authors emphasise that this is due to methodological and/or individual problems, including the accurate timing of saliva collection, the small sample size of studies and the different degree of circadian adaptation to night shift work. Therefore, it is necessary to develop well-defined protocols assessing not only the subjective stress and fatigue but the impact of these variables on the physiological state of workers, using biological markers.