P. Tucker et al., Distribution of rest days in 12 hour shift systems: impacts on health, wellbeing, and on shift alertness, OCC ENVIR M, 56(3), 1999, pp. 206-214
Citations number
24
Categorie Soggetti
Envirnomentale Medicine & Public Health","Pharmacology & Toxicology
Objectives-To investigate of the effects of distribution of rest days in 12
hour shift systems. Although several studies have examined the effects of
compressing work schedules by comparing 8 and 12 hour shift systems, there
is little published research examining the various forms of 12 hour shift s
ystem.
Methods-An abridged version of the standard shiftwork index which included
retrospective alertness ratings was completed by a large sample of industri
al shiftworkers. The respondents worked 12 hour shift systems that either d
id or did not incorporate breaks of >24 hours between the blocks of day and
night shifts. For the purposes of the analysis, each of these two groups w
ere further subdivided into those who started their morning shifts at 0600
and those who started at 0700.
Results-Systems which incorporated rest days between the day and night shif
ts were associated with slightly higher levels of on shift alertness, sligh
tly lower levels of chronic fatigue, along with longer sleep durations when
working night shifts and between rest days. Early changeovers were associa
ted with shorter night sleeps between successive day shifts, but longer and
less disturbed day sleeps between night shifts. These effects of changeove
r time were broadly in agreement with previous research findings.
Conclusions-The distribution of rest days in 12 hour shift systems had only
limited effects on the outcome measures, although the few modest differenc
es that were found favoured systems which incorporated rest days between th
e day and night shifts. It is conceded that the design of the study may hav
e obscured some subtle differences between the shift systems. Nevertheless,
it is concluded that the impact of distribution of rest days seems to be m
inor relative to previously found effects of other features of shift system
s-for example, shift duration.