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Napping and nightshift work: Effects of a short nap on psychomotor vigilance and subjective sleepiness in health workers

Sleep and Biological Rhythms volume 5, pages 117–125 (2007)Cite this article

Abstract

Nightshift is a common work schedule in health environments, and is associated with decreased alertness and increased adverse events at work. This decrease in alertness can be predicted from biological models of sleep homeostasis and circadian influences. Naps can provide a short-term alleviation of sleep need, and the benefits of naps have been demonstrated in laboratory-based studies, and in specific controlled work environments. The efficacy of brief naps has not been demonstrated in health workers in their usual work environment. The current study examined the effects of a 30-min nap break during the nightshift in a cohort of nursing staff and scientists in their usual work environment. Measures of both subjective sleepiness and objective alertness were taken at hourly intervals throughout the nightshift, on nights where a scheduled nap was taken and nights where there was no nap. Following a nap, psychomotor performance metrics (response speed and fastest 10% reactions times) improved and self-reported sleepiness was reduced compared to nights without a nap. These improvements persisted to the end of the nightshift. Effect size estimates suggested that 20–50% of variance in these measures was explained by the interaction of time on shift and the nap intervention. Differences were found in the timing of increases in subjective and objective alertness after the nap. These findings support the effectiveness of a scheduled nap break during a nightshift to maintain alertness in health workers.

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References

  1. Graw P, Krauchi K, Knoblauch V, Wirz-Justice A, Cajochen C. Circadian and wake-dependent modulation of fastest and slowest reaction times during the psychomotor vigilance task. Physiol. Behav. 2004; 80: 695–701.

    CAS  Article  PubMed  Google Scholar 

  2. Monk TH, Buysse DJ, Reynolds CF 3rd et al. Circadian rhythms in human performance and mood under constant conditions. J. Sleep Res. 1997; 6: 9–18.

    CAS  Article  PubMed  Google Scholar 

  3. Wright KP Jr, Hull JT, Czeisler CA. Relationship between alertness, performance, and body temperature in humans. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2002; 283: R1370–7.

    CAS  Article  PubMed  Google Scholar 

  4. Leger D. The cost of sleep-related accidents: a report for the National Commission on Sleep Disorders Research. Sleep 1994; 17: 84–93.

    CAS  PubMed  Google Scholar 

  5. Smith CS, Robie C, Folkard S et al. A process model of shiftwork and health. J. Occup. Health Psychol. 1999; 4: 207–18.

    CAS  Article  PubMed  Google Scholar 

  6. Smith L, Folkard S, Poole CJ. Increased injuries on night shift. Lancet 1994; 344: 1137–9.

    CAS  Article  PubMed  Google Scholar 

  7. Rosekind MR, Smith RM, Miller DL et al. Alertness management: strategic naps in operational settings. J. Sleep Res. 1995; 4: 62–6.

    Article  PubMed  Google Scholar 

  8. Akerstedt T, Peters B, Anund A, Kecklund G. Impaired alertness and performance driving home from the night shift: a driving simulator study. J. Sleep Res. 2005; 14: 17–20.

    Article  PubMed  Google Scholar 

  9. Stutts JC, Wilkins JW, Scott Osberg J, Vaughn BV. Driver risk factors for sleep-related crashes. Accid. Anal. Prev. 2003; 35: 321–31.

    Article  PubMed  Google Scholar 

  10. Bonnet MH, Arand DL. Consolidated and distributed nap schedules and performance. J. Sleep Res. 1995; 4: 71–7.

    Article  PubMed  Google Scholar 

  11. Bonnet MH, Gomez S, Wirth O, Arand DL. The use of caffeine versus prophylactic naps in sustained performance. Sleep 1995; 18: 97–104.

    CAS  PubMed  Google Scholar 

  12. Czeisler CA, Weitzman E, Moore-Ede MC, Zimmerman JC, Knauer RS. Human sleep: its duration and organization depend on its circadian phase. Science 1980; 210: 1264–7.

    CAS  Article  PubMed  Google Scholar 

  13. Dinges DF, Pack F, Williams K et al. Cumulative sleepiness, mood disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4–5 hours per night. Sleep 1997; 20: 267–77.

    CAS  PubMed  Google Scholar 

  14. Jewett ME, Dijk DJ, Kronauer RE, Dinges DF. Dose-response relationship between sleep duration and human psychomotor vigilance and subjective alertness. Sleep 1999; 22: 171–9.

    CAS  PubMed  Google Scholar 

  15. Torsvall L, Akerstedt T, Gillander K, Knutsson A. Sleep on the night shift: 24-hour EEG monitoring of spontaneous sleep/wake behavior. Psychophysiology 1989; 26: 352–8.

    CAS  Article  PubMed  Google Scholar 

  16. Akerstedt T, Folkard S. Validation of the S and C components of the three-process model of alertness regulation. Sleep 1995; 18: 1–6.

    CAS  Article  PubMed  Google Scholar 

  17. Akerstedt T, Folkard S. The three-process model of alertness and its extension to performance, sleep latency, and sleep length. Chronobiol. Int. 1997; 14: 115–23.

    CAS  Article  PubMed  Google Scholar 

  18. Costa G, Akerstedt T, Nachreiner F et al. Flexible work hours, health and well-being in the European Union: preliminary data from a SALTSA project. J. Hum. Ergol. (Tokyo) 2001; 30: 27–33.

    CAS  Google Scholar 

  19. Folkard S, Akerstedt T, Macdonald I, Tucker P, Spencer MB. Beyond the three-process model of alertness: estimating phase, time on shift, and successive night effects. J. Biol. Rhythms 1999; 14: 577–87.

    CAS  Article  PubMed  Google Scholar 

  20. Akerstedt T, Folkard S. Predicting sleep latency from the three-process model of alertness regulation. Psychophysiology 1996; 33: 385–9.

    CAS  Article  PubMed  Google Scholar 

  21. Minors DS, Waterhouse JM. Circadian rhythms and their application to occupational health and medicine. Rev. Environ. Health 1987; 7: 1–64.

    CAS  Article  PubMed  Google Scholar 

  22. Rogers AS, Spencer MB, Stone BM, Nicholson AN. The influence of a 1 h nap on performance overnight. Ergonomics 1989; 32: 1193–205.

    CAS  Article  PubMed  Google Scholar 

  23. Sallinen M, Harma M, Akerstedt T, Rosa R, Lillqvist O. Promoting alertness with a short nap during a night shift. J. Sleep Res. 1998; 7: 240–7.

    CAS  Article  PubMed  Google Scholar 

  24. Rosekind MR, Gander PH, Miller DL et al. Fatigue in operational settings: examples from the aviation environment. Hum. Factors 1994; 36: 327–38.

    CAS  PubMed  Google Scholar 

  25. Purnell MT, Feyer AM, Herbison GP. The impact of a nap opportunity during the night shift on the performance and alertness of 12-h shift workers. J. Sleep Res. 2002; 11: 219–27.

    CAS  Article  PubMed  Google Scholar 

  26. Della Rocco P, Comperatore C, Caldwell L, Cruz C. The Effects of Napping on Night Shift Performance. Federal Aviation Administration, US Department of Transportation. Washington, DC: National Technical Information Service, 2000. Report No. DOT/FAA/AM-00/10.

    Book  Google Scholar 

  27. Cruz C, Della Rocco P, Hackworth C. Effects of quick rotating shift schedules on the health and adjustment of air traffic controllers. Aviat. Space Environ. Med. 2000; 71: 400–7.

    CAS  PubMed  Google Scholar 

  28. Bonnefond A, Muzet A, Winter-Dill AS, Bailloeuil C, Bitouze F, Bonneau A. Innovative working schedule: introducing one short nap during the night shift. Ergonomics 2001; 44: 937–45.

    CAS  Article  PubMed  Google Scholar 

  29. Akerstedt T, Knutsson A, Westerholm P, Theorell T, Alfredsson L, Kecklund G. Mental fatigue, work and sleep. J. Psychosom. Res. 2004; 57: 427–33.

    CAS  Article  PubMed  Google Scholar 

  30. Bonnet MH, Arand DL. Level of arousal and the ability to maintain wakefulness. J. Sleep Res. 1999; 8: 247–54.

    CAS  Article  PubMed  Google Scholar 

  31. Dickman SJ. Dimensions of arousal: wakefulness and vigor. Hum. Factors 2002; 44: 429–42.

    Article  PubMed  Google Scholar 

  32. Hardy GE, Shapiro DA, Borrill CS. Fatigue in the workforce of National Health Service Trusts: levels of symptomatology and links with minor psychiatric disorder, demographic, occupational and work role factors. J. Psychosom. Res. 1997; 43: 83–92.

    CAS  Article  PubMed  Google Scholar 

  33. Goldberg DP, Hillier VF. A scaled version of the General Health Questionnaire. Psychol. Med. 1979; 9: 139–45.

    CAS  Article  PubMed  Google Scholar 

  34. Maldonado CC, Bentley AJ, Mitchell D. A pictorial sleepiness scale based on cartoon faces. Sleep 2004; 27: 541–8.

    PubMed  Google Scholar 

  35. Hart SG, Staveland LE. Development of NASA-TLX (Task Load Index): results of empirical and theoretical research. In: Hancock PA, Meshkati N, eds. Human Mental Workload. Amsterdam: Elsevier Science, 1988; 139–83.

    Chapter  Google Scholar 

  36. Rubio S, Diaz E, Martin J, Puente JM. Evaluation of subjective mental workload: a comparison of SWAT, NASA-TLX, and Workload Profile Methods. Appl. Psychol. Int. Rev. 2004; 53: 61–86.

    Article  Google Scholar 

  37. Thorne DR, Johnson DE, Redmond DP, Sing HC, Belenky G, Shapiro JM. The Walter Reed palm-held psychomotor vigilance test. Behav. Res. Methods 2005; 37: 111–18.

    Article  PubMed  Google Scholar 

  38. Dinges DF, Powell JW. Microcomputer analyses of performance on a portable, simple visual RT task during sustained operations. Behav. Res. Methods Instrum. Comput. 1985; 17: 652–5.

    Article  Google Scholar 

  39. Kribbs NB, Dinges DF. Vigilance decrement and sleepiness. In: Harsh R, Ogilvie RD, eds. Sleep Onset Mechanisms. Washington, DC: American Psychological Association, 1994; 113–25.

    Google Scholar 

  40. Wyatt JK, Ritz-De Cecco A, Czeisler CA, Dijk DJ. Circadian temperature and melatonin rhythms, sleep, and neurobehavioral function in humans living on a 20-h day. Am. J. Physiol. 1999; 277: R1152–63.

    CAS  PubMed  Google Scholar 

  41. Loh S, Lamond N, Dorrian J, Roach G, Dawson D. The validity of psychomotor vigilance tasks of less than 10-minute duration. Behav. Res. Methods Instrum. Comput. 2004; 36: 339–46.

    Article  PubMed  Google Scholar 

  42. Lamond N, Dorrian J, Burgess H et al. Adaptation of performance during a week of simulated night work. Ergonomics 2004; 47: 154–65.

    Article  PubMed  Google Scholar 

  43. Lamond N, Dawson D, Roach GD. Fatigue assessment in the field: validation of a hand-held electronic psychomotor vigilance task. Aviat. Space Environ. Med. 2005; 76: 486–9.

    PubMed  Google Scholar 

  44. Brooks A, Lack L. A brief afternoon nap following nocturnal sleep restriction: which nap duration is most recuperative? Sleep 2006; 29: 831–40.

    PubMed  Google Scholar 

  45. Ferrara M, De Gennaro L. The sleep inertia phenomenon during the sleep-wake transition: theoretical and operational issues. Aviat. Space Environ. Med. 2000; 71: 843–8.

    CAS  PubMed  Google Scholar 

  46. Ferrara M, De Gennaro L, Bertini M. Time-course of sleep inertia upon awakening from nighttime sleep with different sleep homeostasis conditions. Aviat. Space Environ. Med. 2000; 71: 225–9.

    CAS  PubMed  Google Scholar 

  47. Wesensten NJ, Killgore WD, Balkin TJ. Performance and alertness effects of caffeine, dextroamphetamine, and modafinil during sleep deprivation. J. Sleep Res. 2005; 14: 255–66.

    Article  PubMed  Google Scholar 

  48. Tabachnick B, Fidell L. Using Multivariate Statistics. Boston, MA: Allyn & Bacon, 2000.

    Google Scholar 

  49. Rechtschaffen A, Kales A. A Manual of Standardized Terminology. Techniques, and Scoring System for Sleep Stages in Human Subjects, 204 Npn edn. Washington, DC: US Government Printing Office, 1968.

    Google Scholar 

  50. Horne JA. Sleep loss and “divergent” thinking ability. Sleep 1988; 11: 528–36.

    CAS  PubMed  Google Scholar 

  51. Naitoh P, Kelly T, Babkoff H. Sleep inertia: best time not to wake up? Chronobiol. Int. 1993; 10: 109–18.

    CAS  Article  PubMed  Google Scholar 

  52. Bonnet MH, Arand DL. Impact of naps and caffeine on extended nocturnal performance. Physiol. Behav. 1994; 56: 103–9.

    CAS  Article  PubMed  Google Scholar 

  53. Gillberg M. The effects of two alternative timings of a one-hour nap on early morning performance. Biol. Psychol. 1984; 19: 45–54.

    CAS  Article  PubMed  Google Scholar 

  54. Hayashi M, Masuda A, Hori T. The alerting effects of caffeine, bright light and face washing after a short daytime nap. Clin. Neurophysiol. 2003; 114: 2268–78.

    CAS  Article  PubMed  Google Scholar 

  55. Takahashi M, Nakata A, Haratani T, Ogawa Y, Arito H. Post-lunch nap as a worksite intervention to promote alertness on the job. Ergonomics 2004; 47: 1003–13.

    Article  PubMed  Google Scholar 

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Authors and Affiliations

  1. School of Psychology, The University of Queensland, St Lucia, Queensland, 4072, Australia

    Simon S. Smith & Sam Kilby

  2. Queensland Sleep Health Group, Brisbane, Queensland, Australia

    Simon S. Smith, Sam Kilby, Greg Jorgensen & James A. Douglas

  3. The Prince Charles Hospital, Brisbane, Queensland, Australia

    Greg Jorgensen & James A. Douglas

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  1. Simon S. Smith
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  2. Sam Kilby
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  3. Greg Jorgensen
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Correspondence to Simon S. Smith.

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Smith, S.S., Kilby, S., Jorgensen, G. et al. Napping and nightshift work: Effects of a short nap on psychomotor vigilance and subjective sleepiness in health workers. Sleep Biol. Rhythms 5, 117–125 (2007). https://doi.org/10.1111/j.1479-8425.2007.00261.x

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  • DOI: https://doi.org/10.1111/j.1479-8425.2007.00261.x

Key words

  • fatigue
  • nap
  • performance
  • shift work
  • sleepiness