Abstract
Objectives-The generally agreed view is
that there is no ideal shift system, and
that most systems will have both advantages
and disadvantages. As such, attention
has been placed on trying to identify
good and bad features of shift systems,
with a view to minimising the possible ill
health as a consequence of shiftwork. The
present study focuses on the duration of
the shift and looks at the implications for
individual health, wellbeing, and alertness
during the shift of extending the shift
from the traditional eight hours to 12.
Methods-Two groups of chemical workers,
one working 12 hour shifts and the
other working eight hour shifts, took part.
All completed a modified version of the
standard shiftwork index (SSI), a set of
self reported questionnaires related to
health and wellbeing.
Results-The two groups did not differ on
most outcome measures, although the
differences that did exist suggested
advantages for the 12 hour shift workers
over the eight hour shift workers; with the
notable exception of rated alertness at
certain times of day.
Conclusions-The results are explained in
terms of the design of the 12 hour shift
system and the specific sequencing of
shifts that seem to minimise the potential
for the build up of fatigue. Although the
current data moderately favour 12 hour
shifts, a cautionary note is sounded with
regard to the implications of the alertness
ratings for performance and safety.