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October 1990, Volume 40, Issue 10

Original Article


Mohammad Zahir Shah  ( Khyber Medical College, Peshawar. )


Shift work can be attributed to some of social and health problems in working community. In this study an attempt was made to study the sleep and wakefulness patterns in nurses engaged in rotational and non-rotational shift work in a hospital through sleep charts. It was observed that non-rotational workers enjoyed more frequent and longer naps and had less disturbances in their sleep patterns than rotational workers (JPMA 40: 245 , 1990).


Hospitals provide medical and surgical treatment facilities round the clock in the form of different working schedules such as rotational and non-rotational shift work. Most of these working schedules cover night work which involves 8.15% of the economically active population1. Continuous or rapidly changing shifts involving night shift do influence the sleep pattern resulting in ill health due to dept. Thus – Evensen2 observed that more than 50% of shift workers had developed sleep disturbances. Carpen­tier and Cazamain1 reported reduction in the number of sleep hours in shift workers while in a similar study1,3 it was found that shift workers averaged 63 hours of sleep as compared with 7.5 hours by day workers. Similarly Wyatt and Marriot4 observed sleep hours when on the night shift. Sergean5 reported that rotational duties in a particular order has an effect on the net sleep hours. Tune6 found atypical sleep patterns in day workers. Koller et al7 noted that rotating shift workers slept less than the conventional late night to early morning shift workers. Power plant shift workers studies by Mann and Hoffman8 stated that sleep posed the most difficult aspects of working on rotating shifts. Physiological variations or circadian variations in such workers may or may not be adjusted but it may take from a few days to a couple of weeks9 . It has been reported that in some cases adjustment may never occur10,11. However, Kleitman12 indicated that shift workers get less sleep than non-shift workers. This study was undertaken to make an attempt to study sleep and wakefulness patterns in a group of rotational and non-rotational shift nurses and to estahlith the relationship, if any, between sleep disorder and rotational shift work.


A group of sixty female registered nurtes working in a teaching hospital in Sydney initially volunteered to participate in this study. Thirty five of them worked in three rotational shifts while 25 were non-rotational workers. Sleep pattern charts covering a 28 days period were distributed for completion. The charts carried printed instructions for their use and a partially completed specimen chart was also included as a guide. It was emphasised that only the time actually spent asleep was to be recorded and not time spent awake in bed. The sleep charts used in this study were of a type previously used and described by Tune6. Each chart covered a period of 14 days and two charts were given to each nurse, in an attempt to get a 4 week sample. In addition, the nurses were asked to record their hours of work in the remarks column of the charts.


Forty-three of the sixty rotational and non-rotational workers in age group of 25-30 years were considered in this study. The remaining 17 were discarded because most of them failed to return complete data while others did not fall in the above group.
The following dependent measures were extracted from the charts:
a.  The mean duration of sleep per 24 hours.
b.  The number of disturbances of major sleep period per 24 hours.
c.  The mean duration of these disturbances per 24 hours.
d.  The niunber of naps taken outside the major sleep period, and
e.  The mean duration of these naps.
Disturbances of the major sleep period and naps were only taken into account when they lasted longer than 30 minutes ; any such episodes of a briefer duration were not recorded. shows that there were no significant differences between the two groups in terms of dependent sleep measures recorded, which means that rotational workers and non-rotational workers have similar sleep patterns when con­sidered in terms of mean duration of sleep per 24 hours. The number of sleep disturbances of the major sleep period was more significant in these two groups of workers (P <0.05) which showed that rotational workers had more disturbances in their sleep patterns than non-rotational workers but there was no significant difference between these groups as far as the duration of the total number of sleep disturbances was concerned. Another important finding concerned naps taken outside the major sleep period and it was found that there was a significant difference between rotational and non-rotational workers (Pc 0.05). Non-rotational workers en­joyed more frequent and longer naps than the rotational workers.


The data from this study indicate that although rotational workers reported taking a slightly longer mean duration of sleep per day than the non-rotational working controls, the difference was statistically not significant. The non-rotational workers overcame their sleep debts by taking more frequent and longer naps. Another important factor which compensated for the sleep debts in rotational workers was the longer major sleep periods on days oft These findings agree in part with those of a previous study by Tune6. Another major finding was that non-rotational workers relied on taking naps in order to achieve a high mean duration of sleep per day to pay off their sleep debt and the main reason given for this was the early waking to join morning duty. It was assumed that the naps taken outside the major sleep period and of longer duration are an adequate compensation for disturbed or shortened sleep. study showed that rotational workers experienced more sleep disturbances than the non-rotational workers. This could be the result of their irregular working hours and more disturbances in their sleep hours due to the sur­rounding working environment. It is apparent from this study that the rotational workers found it necessary to sleep more than non-rota­tional workers in order to overcome sleep debts and meet the criterion of ‘satisfactory’ sleep.


1. Carpentier, T.O. and Cazamain, P. Night work, Geneva, Interna­tional Labour Office, ILO publications, 1977, p. 36.
2. Thiis-Evensen, B. Shift work and health. Industrial Med. Surg., 1958; 27 : 493.
3. Bjerner, B., HoIm, A. and Swensson, A. Om Nattoch Skiftarbets. Stockholm, Offentliga Utrendinger, 1948, p. 51.
4. Wyatt, S. and Marriot, R. Night work and shift changes. Br.Indus. Med., 1953; 10: 164.
5. Sergean, R. Managing Shiftwork. London, Gower, 1971, p. 116.
6. Tune, G.S. Sleep and wakefulness in a group of shift workers. Br. 3. Indus. Med., 1969; 26: 54.
7. Koller, M., Kundi, M. and Cervinka, R. Field studies of shiftworir at an Austrian oil refinery. Ergonomics, 1978; 21 : 835.
8. Mann, F.C. and Hoffman, L.R. Automation and the worker. New York, Henry Hold, 1968, p.41.
9. Reinberg, A., Vieux, N., Laporte, A., Chata, J. and Migrain, C. Rapid adjustment of circadian rhythms in shift workers; in Proceed­ing of the Sixth Congress of the International Ergonomic Associa­tion, College Park, Maryland 11-16 July, 1967, p.53.
10. Aschoff, 3. Human circadian rhythms inactivity, body temperature and other functions, in A.H. Brown and E.G. Favorite (eds. Life sciences and space research). Edited by Amsterdam, North Hol­land, 1967, p. 79.
11. Rutenfranz, J. and Knauth, P. Investigation of the problems con­cerning influences upon the sleep of shift workers, in Proceeding of the Second International Symposium on night and shift work. Edited by A. Swensson. Stockholm, Institute of Occupational Health, 1970, p.58.
12. Kleitman, N. Sleep and wakefulness. 2nd ed. Chicago, University of Chicago, 1963, p. 101.
13. Masterton, J.P. Sleep of hospital staff. Lancet, 1965; 1 :41.

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