What time do most day shift workers want to start work? Surprisingly, few want to start at 8:00 a.m. or later. Most want to start before 7:00 a.m., as shown in the diagram below.
Why do so many people want to start work early? Workers tell us there are two reasons.
First, they want to get home earlier. It may be possible to arrive at home around the same time their children get out of school. There is more time in the evening to run personal errands or spend time with the family and friends. And, of course, there are more hours of daylight available for recreation, house repairs, or anything else best done while the sun is out.
Shiftworker Preferred Start Times
Median for 8-hour shifts = 6:30 a.m.
Median for 12-hour shifts = 6:00 a.m.
The second reason is they want to avoid traffic congestion during the commute to and from work. Nobody enjoys sitting in stalled traffic or poking along at a fraction of the posted speed limit. By starting work a little earlier, workers can avoid the rush hour and spend less time on the road. More than one shift worker has told us that by starting 15 minutes earlier they saved up to 45 minutes on their commute.
In addition, preferred work start times are heavily influenced by what people are familiar with. The graph below shows the preferred start times from two companies whose actual start times are significantly different. In both cases, the employees would like to have earlier start times. But the average preferences at the two plants are more than an hour apart. Clearly, the preferred start times are tempered by what the workers are used to. Once a start time is changed, preferences will gradually evolve, making acceptance of any change in start times a long-term process.
Preferred Start Times at Two Different Companies
| A |
Company A
|
Company B |
|
Current start time
|
6:30 a.m.
|
8:00 a.m. |
| Preferred start time (average) |
6:27 a.m. |
7:37 a.m.
|
What most people don't realize, however, is that early start times often result in less sleep. Why? Because most people won't go to bed earlier to adjust for an early work start time. They would rather sacrifice their sleep than their normal evening activities.
Here is an example from a major auto parts manufacturing plant. The plant operates on two different schedules that are an hour apart. Three-quarters of the workers on day shift start work at 6:30 a.m. The rest start an hour later at 7:30 a.m.
When surveyed, employees with the later starting time said they got an average of 34 minutes more sleep on the days they worked than the employees with the early start time did. The later start time simply allowed them to sleep longer. On their days off, both groups got about the same amount of sleep.
Asked how often they had problems with safety or performance due to sleepiness, the group with the later starting time reported they had frequent problems 31% less often than the employees on the earlier day shift. In addition, the “later starters” accounted for only 14% of the accidents over a one-year period, despite representing 24% of the total workers.
The later start times had mixed results with the afternoon and night shifts at the plant. As seen in the table below, the second shift with late start times got a little more sleep and the third shift with late start times got a little less sleep. The day shift was the only shift that experienced a significant change.
|
Shift
|
Average Hours of Sleep
|
Difference
|
|
Early Start
|
Late Start
|
|
Day shift
|
5.78 hours/day
|
6.34 hours/day
|
+34 minutes
|
|
Afternoon shift
|
6.46 hours/day
|
6.59 hours/day
|
+8 minutes
|
|
Night shift
|
5.98 hours/day
|
5.80 hours/day
|
-11 minutes
|
This is not an isolated case. The National Institute for Occupational Safety and Health (NIOSH) and the Finnish Institute of Occupational Health found that a one-hour delay in morning shift start times at a steel mill increased worker sleep and improved waking alertness during the shift. They believe that sleep is often truncated when workers have early start times. The reason? Social limitations on retiring early in the evening. They also found that the evening and night shifts were affected negatively by starting work later, however, the results were not consistent.
The evidence seems to be consistent in supporting the conclusion that later start times increase the hours of sleep, at least for people working the morning shift. The question is whether the workers would choose later start times when given the choice. Does the advantage of extra sleep outweigh the disadvantages of longer commute times and less free time after work? And what about people working the other shifts? They didn't gain the same benefits, so why should they support a change?
In the NIOSH/Finnish study, the workers were allowed to vote on changing the schedule after a four-month trial of later start times. 75% of the workers voted against the later start times. The workers explained that this choice was unpopular because it interfered with social and other personal activities. How do you think your workforce would vote? Don't you think it's worth giving them the opportunity to decide? Before you do, make sure they are familiar with the studies described in this article.
Sources
1. Roger R Rosa, Mikko Harma, Katriina Pulli, Mirjam Mulder, Ove Nasman, “Rescheduling a three shift system at a steel rolling mill: effects of a one hour delay of shift starting times on sleep and alertness in younger and older workers,” Occupational andEnvironmental Medicine, Oct. 1996, Volume 53, No. 10, pp.677-685.
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