|
Shift Workers
Last edited |
06/09/2006
A well-known risk factor for insomnia and excessive daytime
sleepiness complaints are working conditions, especially shift work
The rate of sleep
complaints in this specific population is higher than rates found in the general
population.
These problems are
mainly due to a disruption of the normal sleep/wake rhythm, of the normal
circadian REM sleep rhythm and of the rhythm of REM/non-REM sleep patterns.
Thus, the sleep
problems of shift workers are partly a circadian one.
Several studies have
reported that the total sleep duration is related to the body temperature rhythm
at bedtime.
Studies using a sleep diary of workers as well as laboratory
studies have shown that the main sleep period at an unusual time is one to four
hours shorter than night sleep.
However, other factors are also involved
in the deterioration of sleep quality:
-
fatigue,
-
stress,
-
daylight,
-
health,
-
and
age.
Whether these disorders are causing more sick leaves in shift workers is
unclear: previous studies have reported contradictory results in this respect:
-
some found a lower
absence rate in shift workers than in day workers,
-
while others found
higher rates of sick leave and a higher number of visits to work site clinics in
shift workers.
These contradictory results have lead some researchers to
hypothesize that there may be a natural selection process among shift workers:
those having difficulties adapting to shift work usually transfer to day work.
The rare studies that
have tested this hypothesis tend to confirm it.
The occurrence of
sleep disturbances appeared to be a good marker of the adjustment level to shift
work.
One of the main
consequences of having the main sleep period at an unusual time is an excessive
sleepiness during wakefulness.
This phenomenon is
often evoked when attempting to explain human catastrophes occurring at night
such as the Chernobyl nuclear accident, airplane crashes and road accidents.
Furthermore, decreased
vigilance may cause the individual to be more vulnerable to work-related
accidents.
Research
We investigated the effects on sleep of three different work schedules among the
staff of a psychiatric hospital:
Two physicians using the Sleep-EVAL system interviewed 817 staff members of a
psychiatric hospital.
The interviews were done during the working hours.
In
addition to a series of questions to evaluate sleep and mental disorders, the
evaluation included a standard questionnaire assessing work conditions, work
schedule and their consequences.
Three work schedules were assessed:
-
fixed daytime schedule (n=442);
-
rotating daytime shifts (n=323);
-
shift or nighttime work (n=52).
Results
Subjects working on rotating daytime shifts were younger than the two other
groups and had a higher proportion of women.
Participants working on rotating
daytime shifts reported more frequently than the fixed daytime schedule workers
to have difficulty initiating sleep (20.1% vs. 12.0%).
The sleep duration of
shift or nighttime workers was shorter than that of the two other groups.
Furthermore, subjects working rotating daytime schedule reported to have shorter
sleep duration of about 20 minutes when they are assigned to the morning shift.
Work-related accidents were two times more frequent among the rotating daytime
workers (19.5%) compared with the fixed daytime schedule workers (8.8%) and the
group of nighttime or shift workers (9.6%).
Sick leaves in the previous 12
months were also more frequently reported in the rotating daytime schedule group
(62.8%) as compared with the daytime group (38.5%; p<.001); 51.9% of nighttime
or shift workers took sick leave.
Working on a rotating daytime shifts causes significant sleep disturbances.
As
consequence, these workers are:
|
Sleep-EVAL
Research
