Topic 2: Biological Rhythms: Czeisler et al (1982) Flashcards
(Topic 2: Czeisler) What was the aim of the study?
To investigate the effects of taking into account circadian rhythms when designing work schedules – specifically the direction in which shifts are rotated and the intervals between these shifts.
(Topic 2: Czeisler) Describe the sample.
85 male rotating shift workers at a potash factory in Utah USA, they were aged 19-68, and were compared to a control group of 68 male non rotating shift workers.
(Topic 2: Czeisler) Describe the original work schedule of the sample.
Phase advance: For 10 years they had been using a 7 day work schedule. They would do an 8 hour shift and then after a week move to the preceding shift.
- Midnight – 8 a.m. for 7 days
- 4 p.m. to midnight for 7 days
- 8 a.m. to 4 p.m. for 7 days
(Topic 2: Czeisler) State the measures within the study. (4)
Self report measures found that those on the rotating shifts had more issues with insomnia.
29% reported they had fallen asleep at work at least once during the previous 3 months.
90% of the rotators complained their schedules changed too often.
80% of them reported it took 2 – 4 days for their sleep to adjust after each phase advance.
(Topic 2: Czeisler) Describe how Czeisler intervened.
He educated all employees on the basic properties of the circadian sleep wake cycle and gave suggestions for how they could adjust their sleep time to their work schedule. He then divided the 85 workers on rotating shifts into 2 groups all were moved to a phase delay schedule.
(Topic 2: Czeisler) Describe how Czeisler managed night shifts.
The other change Czeisler et al made was for some employees to rotate their shifts every 7 days.
Other employees would rotate their shifts every 21 days,
(Topic 2: Czeisler) State what happened after 3 and 9 months.
After 3 months the workers were given a questionnaire about their preferences.
After 9 months personnel turnover and plant productivity were analysed.
(Topic 2: Czeisler) Results: What did significantly more workers prefer?
Significantly more workers preferred the new phase delay work schedule.
(Topic 2: Czeisler) Results: What percentage did complaints drop amongst the workers on the 21 day phase delay rotation schedule?
20%
(Topic 2: Czeisler) Results: What group was more satisfied with their new schedule?
The workers on the 21 day phase delay rotation schedule were significantly more satisfied with their schedule than those on the 7 day rotation schedule.
(Topic 2: Czeisler) Results: How was the health index impacted?
They also reported increased scores on a health index.
(Topic 2: Czeisler) Results: Describe the results regarding staff turnover after 9 months of the new rotation schedules.
Staff turnover on the 21 day phase delay schedule was reduced to the same range as a comparable control group of non-rotating shift workers.
(Topic 2: Czeisler) Results: Describe the resulting regarding the rate of potash harvesting and processed potash production.
There was also an increased rate of potash harvesting and processed potash production after the introduction of the new 21 day phase delay rotation schedule.
(Topic 2: Czeisler) State the conclusion for this research.
Work schedules that use phase delay with an extended interval between each rotation are most compatible with the properties of human circadian timing systems.
