Document Type : Original Articles


1 Department of Occupational Health, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran

2 Department of Epidemiology, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran


Background: The present study aimed to investigate the effects of work shifts and mental workload on chronic fatigue among female nurses in Intensive Care Units of selected hospitals in Shiraz. Methods: The participants in this cross-sectional study were 118 female nurses working in Intensive Care Units of three hospitals in Shiraz with an average age of 304.8± years. SP (Samn-Perelli) Mental fatigue scale and NASA task load index were rated for two weeks at the beginning and end of each work shift. The Checklist Individual Strenght (CIS) questionnaire was completed to assess the fatigue during the last two weeks. Results: Mean score of chronic fatigue was 69.2±13. Menal fatigue and mental workload per shift were significantly correlated with work shifts (P=0.001). Mental workload (P=0.006, r=0.24) and mental fatigue caused by work shifts (P=0.001, r=0.42) were also significantly correlated with chronic fatigue. Conclusion: The results of the study showed that mental workload and work shifts influence the nurses’ fatigue in Intensive Care Units. Therefore, using intervention strategies to reduce mental work load and modification of shift work system in this group seems to be necessary.


  1. Harrington JM. Health effects of shift work and
  2. extended hours of work. Occup Environ Med 2001; 58(1): 68-72.
  3. Haus E, Smolensky M. Biological clocks and shift
  4. work: circadian dysregulation and potential long-term
  5. effects. Cancer causes control 2006; 17(4): 489-500.
  6. Zamanian Z, Kakooei H, Ayattollahi SMT, Dehghani
  7. M. Effect of bright light on shift work nurses in
  8. hospitals. Pak J Biol Sci 2010; 13(9): 431-6.
  9. Zamanian Z, Mohammadi H, Rezaeeyani MT,
  10. Dehghani M. An investigation of shift work disorders
  11. in security personnel of 3 hospitals of Shiraz University
  12. of Medical Sciences, 2009. Iran Occupational Health
  13. ; 9(1): 52-7.
  14. Zamanian Z, Dehghani M, Hashemi H. Outline of
  15. changes in cortisol and melatonin circadian rhythms
  16. in the security guards of Shiraz University of Medical
  17. Sciences. Int J Prev Med 2013; 4(7): 825-30.
  18. Batak T, Gvozdenović L, Bokan D, Bokan D. The
  19. impact of nurses’ shift work on the fatigue level. south
  20. estern europe health sciences journal 2013; 3(2): 120-27.
  21. de Cordova PB, Phibbs CS, Bartel AP, Stone PW.
  22. Twenty-four/seven: a mixed-method systematic review
  23. of the off-shift literature. J Adv Nurs 2012; 68(7):
  24. -68.
  25. Esquirol Y, Bongard V, Mabile L, Jonnier B, Soulat
  26. J-M, Perret B. Shift work and metabolic syndrome:
  27. respective impacts of job strain, physical activity, and
  28. dietary rhythms. Chronobiol Int 2009; 26(3): 544-59.
  29. Young G, Zavelina L, Hooper V. Assessment of workload
  30. using NASA Task Load Index in perianesthesia nursing.
  31. J Perianesth Nurs 2008; 23(2): 102-10.
  32. Sharma A, Verma A, Malhotra D. Job performanceand
  33. chronic fatigue syndrome in nurses. Asian Social
  34. Science 2010; 6(12): p167.
  35. Barker LM, Nussbaum MA. Fatigue, performance and
  36. the work environment: a survey of registered nurses. J
  37. Adv Nurs 2011; 67(6): 1370-82.
  38. Silva AA, Rotenberg L, Fischer FM. Nursing work
  39. hours: individual needs versus working conditions.
  40. Rev Saúde Pública 2011; 45(6): 1117-26.
  41. Fletcher A, Dawson D. Field-based validations of a
  42. work-related fatigue model based on hours of work.
  43. Transportation research part F: traffic psychology and
  44. behaviour 2001; 4(1): 75-88.
  45. Berger AM, Hobbs BB. Impact of shift work on the
  46. health and safety of nurses and patients. Clin J Oncol
  47. Nurs 2006; 10(4): 465-71.
  48. Mann MB. Testimony: National Aeronautics and
  49. Space Administration Hearing on Pilot Fatigue before
  50. the Aviation Sub Committee of the Committee on
  51. Transportation Infrastructure. United States House
  52. of Representatives.
  53. Gander P, Hartley L, Powell D, Cabon P, Hitchcock E,
  54. Mills A, et al. Fatigue risk management: Organizational
  55. factors at the regulatory and industry/company level.
  56. Accid Anal Prev 2011; 43(2): 573-90.
  57. Baulk SD, Kandelaars KJ, Lamond N, Roach GD, Dawson D, Fletcher A. Does variation in workload
  58. affect fatigue in a regular 12-hour shift system? Sleep
  59. and Biological Rhythms 2007; 5(1): 74-7.
  60. Carayon P, Gürses AP. A human factors engineering
  61. conceptual framework of nursing workload and patient
  62. safety in intensive care units. Intensive Crit Care Nurs
  63. ; 21(5): 284-301
  64. Grech MR, Neal A, Yeo G, Humphreys M, Smith S.
  65. An examination of the relationship between workload
  66. and fatigue within and across consecutive days of work:
  67. Is the relationship static or dynamic? J Occup Health
  68. Psychol 2009; 14(3): 231-42.
  69. Sherwood W. Samn LPP. Estimating aircrew fatigue:
  70. a technique with aplication to airlift operations. USAF
  71. school of aerospace medicine, 1982.
  72. Gander PH, Mulrine HM, Berg MJ, Smith AAT,
  73. Signal TL, Wu LJ, et al. Effects of sleep/wake history
  74. and circadian phase on proposed pilot fatigue safety
  75. performance indicators. J Sleep Res 2015; 24(1): 110-9.
  76. Hart SG, Staveland LE. Development of NASA-TLX
  77. (Task Load Index): Results of empirical and theoretical
  78. research. Advances in psychology 1988; 52: 139-83.
  79. Moroney WF, Biers DW, Eggemeier FT, Mitchell JA,
  80. editors. A comparison of two scoring procedures with
  81. the NASA task load index in a simulated flight task.
  82. Aerospace and Electronics Conference, 1992NAECON
  83. , Proceedings of the IEEE 1992 National; 1992:
  84. -40.
  85. Safari S, Mohammadi H, Kazemi M. Evaluation Mental
  86. Work Load in Nursing Critical Care Unit with National
  87. Aeronautics and Space Administration Task Load Index
  88. (NASA-TLX). J Health Syst Res 2013;9(6): 613-19.
  89. Vercoulen JH, Swanink C, Fennis JF, Galama J, van
  90. der Meer JW, Bleijenberg G. Dimensional assessment
  91. of chronic fatigue syndrome. J Psychosom Res 1994;
  92. (5): 383-92.
  93. Habibi EA, Parvari RA, Khodarahmi B, Dehghan HA,
  94. Hosseini M. Assessment of the Relationship between
  95. Work Schedule and Fatigue among the Emergency
  96. Personnel of Isfahan, Iran Using the Checklist
  97. Individual Strength Standard Method. Scientific
  98. Journal of School of Public Health and Institute of
  99. Public Health Research 2011; 7(6): 1288-96.
  100. Trinkoff A, Geiger-Brown J, Brady B, Lipscomb J,
  101. Muntaner C. How Long and How Much Are Nurses
  102. Now Working? Am J Nurs 2006; 106(4): 60-71.
  103. Ingre M, Kecklund G, Åkerstedt T, Kecklund L.
  104. Variation in sleepiness during early morning shifts: a
  105. mixed model approach to an experimental field study
  106. of train drivers. Chronobiol Int 2004; 21(6): 973-90.
  107. Baulk SD, Fletcher A, Kandelaars K, Dawson D, Roach
  108. G. A field study of sleep and fatigue in a regular rotating
  109. -h shift system. Appl Ergon 2009; 40(4): 694-8.
  110. Myny D, Van Goubergen D, Gobert M, Vanderwee
  111. K, Van Hecke A, Defloor T. Non-direct patient care
  112. factors influencing nursing workload: a review of the
  113. literature. J Adv Nurs 2011; 67(10): 2109-29.
  114. Myny D, Van Hecke A, De Bacquer D, Verhaeghe
  115. S, Gobert M, Defloor T, et al. Determining a set of
  116. measurable and relevant factors affecting nursing
  117. workload in the acute care hospital setting: A crosssectional
  118. study. Int J Nurs Stud 2012; 49(4): 427-36.
  119. Seago JA, Spetz J, Mitchell S. Nurse staffing and
  120. hospital ownership in California. J Nurs Adm 2004; 34(5): 228-37.
  121. Dorrian J, Baulk SD, Dawson D. Work hours, workload,
  122. sleep and fatigue in Australian Rail Industry employees.
  123. Appl Ergon 2011; 42(2): 202-9.
  124. Samaha E, Lal S, Samaha N, Wynahm J. Psychological,
  125. lifestyle and coping contributors to chronic fatigue in
  126. shift-worker nurses. J Adv Nurs 2007; 59(3): 221-32.