Hospital Shift Workers

Last edited   | 12/11/2011

Adapted by Maurice M. Ohayon, MD, DSc, PhD

Reference to cite: Ohayon MM, Lemoine P, Arnaud-Briand V, Dreyfus M. Prevalence and consequences of sleep disorders in a shift worker population. J Psychosom Res 2002; 53:577-583.

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:

• fixed daytime schedule,

• rotating daytime schedule and

• shift or night working.

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:

• more likely to feel sleepy at work and

• are more likely to have work-related accidents and sick leaves.