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Citation Information : Eat, Sleep, Work. Volume 1, Issue 1, Pages 39-56, DOI: https://doi.org/10.21913/JDRSSesw.v1i1.1224
License : (CC BY-NC-ND 3.0)
Split shift schedules which minimise consecutive hours awake and maintain adequate total sleep time per 24h may be a suita-ble alternative to long shifts. However, when returning to a daytime schedule (RTDS), performance and sleep deﬁcits may occur as a result of changing the timing of sleep and wake periods. The ﬁrst aim of the current study was to check whether ﬁxed and rotating split shift schedules with 20h time in bed (TIB) per 48h minimised cumulative deﬁcits in sleep, performance and mood. The second aim was to investigate whether RTDS following these shift schedules had a negative impact on sleep, per-formance and mood. Twenty four participants (10M, 2136y) completed a 9-day laboratory study with two 10h baseline sleeps (22:00h-08:00h); one of three shift conditions for four 24h periods: one of two 6h on / 6h off schedules, (Fixed A: 5h TIB at 03:00h/15:00h, or Fixed B: 5h TIB at 09:00h/21:00h), or an 8h on / 8h off schedule (Rotating: 6h40 TIB); and RTDS with 10h TIB for 2-nights (22:00h-08:00h). Psychomotor vigilance was stable throughout the shift schedule period. Subjective sleepi-ness (p<0.001), positive affect (p<0.01) and negative affect (p<0.001) were all signiﬁcantly worse by the second 48h shift schedule period (SS2) compared to baseline (BL). Amount of Stage R sleep was signiﬁcantly lower by SS2 compared to BL. Subjective sleepiness and positive affect returned to BL levels upon RTDS. Negative affect was signiﬁcantly higher than BL upon RTDS (p<0.001). Stage R sleep was not signiﬁcantly different to BL upon RTDS, however amount of N3 sleep upon RTDS was signiﬁcantly reduced compared to BL in the Fixed B condition. For all conditions, sleep onset latency, N2 onset latency and N3 onset latency were signiﬁcantly longer during RTDS compared to baseline (p<0.05). Consistent with previous litera-ture, split shift schedules did not result in cumulative impairments to sleep and performance. However, ﬁndings suggest that workers may still experience sleepiness and worsened mood. Switching back to a daytime schedule may also result in delays in falling asleep and also deep sleep.
1. ABS (Australian Bureau of Statistics). Working Time Arrangements. 2012 Cat. no. 6342.0. Retrieved 20 July 2015, from http://www.abs.gov.au/AUSSTATS/abs@. nsf/Lookup/6342.0Main+Features1November%20 2012?OpenDocument
2. Folkard S, Tucker P. Shift work, safety and productivity. Occup Med. 2003;53(2):95-101.
3. Rajaratnam SMW, Arendt J. Health in a 24-h society. Lancet. 2001;358(9286):999-1005.
4. Crowley SJ, Lee C, Tseng CY, Fogg LF, Eastman CI. Complete or partial circadian re-entrainment improves performance, alertness, and mood during night-shift work. Sleep. 2004;27(6):1077.
5. Dinges DF, Pack F, Williams K, Gillen KA, Powell JW, Ott GE, Aptowicz C, Pack AI. Cumulative sleepiness, mood disturbance and psychomotor vigilance performance decrements during a week of sleep restricted to 4-5 hours per night. Sleep. 1997;20(4):267-277.
6. Åkerstedt T, Wright Jr KP. Sleep loss and fatigue in shift work and shift work disorder. Sleep Med Clin. 2009;4(2):257-271.
7. Dijk, D-J, Duffy, JF, & Czeisler, CA. Circadian and sleep/ wake dependent aspects of subjective alertness and cognitive performance. J Sleep Res. 1992;1(2):112-117.
8. Åkerstedt, T, & Gillberg, M. The circadian variation of experimentally displaced sleep. Sleep. 1980;4(2):159-169.
9. Borbély AA, Achermann P. Sleep homeostasis and models of sleep regulation. J Biol Rhythms. 1999;14(6):559-570.
10. Dijk D-J, Hayes B, Czeisler CA. Dynamics of electroencephalographic sleep spindles and slow wave activity in men: effect of sleep deprivation. Brain Res. 1993;626(1):190-199.
11. Costa G. The impact of shift and night work on health. Appl Ergon, 1996;27(1):9-16.
12. Eriksen CA, Gillberg M, Vestergren P. Sleepiness and sleep in a simulated “six hours on/six hours off” sea watch system. Chronobiol Int. 2006;23(6):1193-1202.
13. Hansen JH, Holmen IM. Sleep disturbances among offshore ﬂeet workers. A questionnaire-based survey. Int Marit Health. 2011;62(2):123-130.
14. Härmä M, Partinen M, Repo R, Sorsa M, Siivonen P. Effects of 6/6 and 4/8 watch systems on sleepiness among bridge ofﬁcers. Chronobiol Int. 2008;25(2-3):413423.
15. Jay SM, Dawson D, Lamond N. Train drivers’ sleep quality and quantity during extended relay operations. Chronobiol Int. 2006;23(6):1241-1252.
16. Lützhöft M, Dahlgren A, Kircher A, Thorslund B, Gillberg M. Fatigue at sea in Swedish shipping—a ﬁeld study. Am J Ind Med. 2010;53(7):733-740.
17. Sanquist TF, Raby M, Forsythe A, Carvalhais AB. Work hours, sleep patterns and fatigue among merchant marine personnel. J Sleep Res. 1997;6(4):245-251.
18. van Leeuwen WMA, Kircher A, Dahlgren A, Lützhöft M, Barnett M, Kecklund G, Åkerstedt T. Sleep, sleepiness, and neurobehavioral performance while on watch in a simulated 4 hours on/8 hours off maritime watch system. Chronobiol Int. 2013;30(9):1108-1115.
19. Short MA, Agostini A, Lushington K, Dorrian J. A systematic review of the sleep, sleepiness, and performance implications of limited wake shift work schedules. Scand J Work Env Hea. 2015;41(5):425-440.
20. Van Dongen HPA, Belenky G, Vila BJ. The efﬁcacy of a restart break for recycling with optimal performance depends critically on circadian timing. Sleep. 2011;34(7):917-929.
21. Jackson ML, Banks S, Belenky G. Investigation of the effectiveness of a split sleep schedule in sustaining sleep and maintaining performance. Chronobiol Int. 2014;31(10):1218-1230.
22. Härmä M, Tarja H, Irja K, Mikael S, Jussi V, Anne B, Pertti M. A controlled intervention study on the effects of a very rapidly forward rotating shift system on sleep– wakefulness and wellbeing among young and elderly shift workers. Int J Psychophysiol. 2006;59(1):70-79.
23. Ferguson SA, Kennaway DJ, Baker A, Lamond N, Dawson D. Sleep and circadian rhythms in mining operators: limited evidence of adaptation to night shifts. Appl Ergon. 2012;43(4):695-701.
24. Barnes CM, Wagner DT. Changing to daylight saving time cuts into sleep and increases workplace injuries. J Appl Psychol. 2009;94(5):1305-1317.
25. Kosmadopoulos A, Sargent C, Darwent D, Zhou X, Dawson D, Roach GD. The effects of a split sleep– wake schedule on neurobehavioural performance and predictions of performance under conditions of forced desynchrony. Chronobiol Int. 2014;31(10):1209-1217.
26. Mollicone DJ, Van Dongen H, Rogers NL, Dinges DF. Response surface mapping of neurobehavioral performance: testing the feasibility of split sleep schedules for space operations. Acta astronaut. 2008;63(7):833-840.
27. Smith CS, Reilly C, Midkiff K. Evaluation of three circadian rhythm questionnaires with suggestions for an improved measure of morningness. J Appl Psychol. 1989;74(5):728.
28. Buysse DJ, Reynolds CF, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989;28(2):193-213.
29. Carskadon MA, Rechtschaffen A. Monitoring and staging human sleep. In: Kryger MH, Roth T, Dement W, editors. Principles and Practice of Sleep Medicine (pp. 943-960). Philadelphia: W.B. Saunders; 2005.
30. Silber MH, Ancoli-Israel S, Bonnet MH, Chokroverty S, Grigg-Damberger MM, Hirshkowitz M, Kapen S, Keenan SA, Kryger MH, Penzel T, Pressman MR, Iber C. The visual scoring of sleep in adults. J Clin Sleep Med. 2007;3(2):121-131.
31. Dorrian J, Rogers NL, Dinges DF. Psychomotor vigilance performance: neurocognitive assay sensitive to sleep loss. In: Kushida CA, editor. Sleep Deprivation – Clinical Issues, Pharmacology, and Sleep Loss Effects. New York City, NY: Marcel Dekker New York; 2005.
32. Åkerstedt T, Gillberg M. Subjective and objective sleepiness in the active individual. Int J Neurosci. 1990;52(1-2):29-37.
33. Kaida K, Takahashi M, Åkerstedt T, Nakata A, Otsuka Y, Haratani T, Fukasawa K. Validation of the Karolinska sleepiness scale against performance and EEG variables. Clin Neurophysiol. 2006;117(7):1574-1581.
34. Watson D, Clark LA, Tellegen A. Development and validation of brief measures of positive and negative affect: the PANAS scales. J Pers Soc Psychol. 1988;54(6):1063-1070.
35. Crawford JR, Henry JD. The Positive and Negative Affect Schedule (PANAS): construct validity, measurement properties and normative data in a large non-clinical sample. Br J Clin Psychol. 2004;43(3):245-265.
36. Watson D, Wiese D, Vaidya J, Tellegen A. The two general activation systems of affect: structural ﬁndings, evolutionary considerations, and psychobiological evidence. J Pers Soc Psychol. 1999;76(5):820-838.
37. Crawford JR, Garthwaite PH, Lawrie CJ, Henry JD, MacDonald MA, Sutherland J, Sinha P. A convenient method of obtaining percentile norms and accompanying interval estimates for self-report mood scales (DASS, DASS-21, HADS, PANAS, and sAD). Br J Clin Psychol. 2009;48(2):163-180.
38. Lamond N, Dorrian J, Roach GD, McCulloch K, Holmes A, Burgess HJ, Fletcher A, Dawson D. The impact of a week of simulated night work on sleep, circadian phase, and performance. Occup Environ Med. 2003;60(11):e13.
39. Monk TH, Wagner JA. Social factors can outweigh biological ones in determining night shift safety. Hum Factors. 1989;31:721-724.
40. Costa, G. Shift work and occupational medicine: an overview. Occup Med. 2003;53(2):83-88.
41. Brunner DP, Dijk D-J, Tobler I, Borbély AA. Effect of partial sleep deprivation on sleep stages and EEG power spectra: evidence for non-REM and REM sleep homeostasis. Electroencephalogr Clin Neurophysiol, 1990;75(6):492-499.
42. Dijk D-J, Czeisler CA. Contribution of the circadian pacemaker and the sleep homeostat to sleep propensity, sleep structure, electroencephalographic slow waves, and sleep spindle activity in humans. J Neurosci. 1995;15(5):3526-3538.
43. Lundh LG, Broman JE. Insomnia as an interaction between sleep-interfering and sleep-interpreting processes. J Psychosom Res. 2000;49(5):299-310.
44. Thomsen DK, Yung Mehlsen M, Christensen S, Zachariae R. Rumination—relationship with negative mood and sleep quality. Pers Individ Differ. 2003;34(7):1293-1301.
45. Dorrian J, Lamond N, Holmes AL, Burgess HJ, Roach GD, Fletcher A, Dawson D. The ability to self-monitor performance during a week of simulated night shifts. Sleep. 2003;26(7):871-877.
46. Tilley AJ, Wilkinson RT, Warren PSG, Watson B, Drud M. The sleep and performance of shift workers. Hum Factors. 1982;24(6):629-641.
47. Belenky G, Wesensten NJ, Thorne DR, Thomas ML, Sing HC, Redmond DP, Russo MB, Balkin TJ. Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: a sleep doseresponse study. J Sleep Res. 2003;12(1):1-12.
48. Mollicone DJ, Van Dongen H, Rogers NL, Banks S, Dinges DF. Time of day effects on neurobehavioral performance during chronic sleep restriction. Aviat Space Environ Med. 2010;81(8):735-744.
49. Tassi P, Muzet A. Sleep inertia. Sleep Med Rev. 2000;4(4):341-353.
50. Knutsson A. Health disorders of shift workers. Occup Med. 2003;53(2):103-108.