Background. Shift work is associated with sleep and health problems. Tolerance to shift work is
reported to decrease with age. Shift work tolerance should be considered in different shift work
populations. The aim of the study was to examine the relationship between age, shift work
exposure, shift type, and morningness and sleep/health problems in oil rig shift workers.
Material and methods. A total of 199 workers participated. They worked either two weeks of
12-h day shifts (n = 96) or two weeks of swing shifts (n = 103) (one week of 12-h night shifts
followed by one week of 12-h day shifts), followed by four weeks off work. The workers filled out
questionnaires on demographics, work, sleep, and health.
Results. We found no significant associations between age or years of shift work exposure and
any of the sleep, sleepiness, or health parameters. There was a significant association between
shift type and sleep duration, showing that swing shift workers had longer sleep duration than
day shift workers. In addition, we found a significant association between the interaction age*,
shift type, and sleep duration, where sleep duration was negatively associated with age for the
swing shift workers and positively associated with age for the day shift workers. There were
significant associations between morningness and sleep latency, sleep efficiency, and insomnia.
Conclusions. Older workers may tolerate shift work well. Age, shift work exposure time, and shift
type seemed not to affect shift work tolerance in this population. However, this may be due to
a healthy worker effect and/or selection bias.
(Int Marit Health 2010; 61; 4: 251-257