Posts

Schedule variability linked to fatigue and human factors incidents

Working-Schedule

Schedule variability linked to fatigue and human factors incidents in new US Department of Transportation, Federal Railroad Association study.

In April 2014, the US Department of Transportation’s Federal Railroad Association (FRA) released a new report which examines a link between work shift start time variability and an increased risk of human factors accidents.

Their research concluded that in fact, the greater the inconsistency in the time of day works shifts are scheduled to start, the greater the level of worker fatigue and associated accident risk.

To assist in reaching these conclusions, Fatigue Science’s Fatigue Avoidance Scheduling Tool (FAST) was used to measure the level of fatigue in various work schedule scenarios. The FRA researchers used a FAST score below 90 [1] to determine if fatigue was present, and then measured the amount of time workers spent below that criterion during their working hours.

Where schedules (during which an accident had occurred) exhibited a high rate of start time variability, FAST demonstrated the workers were spending as much as 50-60% of their time below the fatigue score criterion that was set for this study.

The report concludes:

Fatigue, as measured by the FAST score, was also shown to be a function of start time variability. While it was previously demonstrated that fatigue was a general function of sleep and work schedules (Raslear et al., 2011), this report extends that finding to specify start time variability as a critical aspect of work schedules when considering fatigue and the probability of an accident.

Key takeaways:

  • FAST technology is trusted by the US Department of Transportation, Federal Railroad Administration as a tool for accurately predicting fatigue and levels of fatigue in their work schedules
  • Fatigue is not only a factor for night shift or rotating shift workers
  • Day shift workers can be subject to increased levels of fatigue if their work shift start times are inconsistent.
  • Evidence-based decisions can be made that effectively reduce fatigue without adversely affecting operations.

1. The Fatigue Avoidance Scheduling Tool (FAST) uses scientifically-valid modelling algorithms to measure potential fatigue in work schedules – retrospectively for incident analysis, or in future schedules to optimize planning. FAST identifies that a score of 90 is associated with a 10% reduction in reaction time and 1.5x increased likelihood of a long lapse (or microsleep) – these associated performance changes increase as the FAST score for a schedule roster or worker lowers.

Think you are performing your best with 6 hours of sleep?

Science says…‘Better go back to bed’

This week, sleep advocate and Huffington Post editor-in-chief, Arianna Huffington, released a substantial blog post rounding up some of the recent coverage in the media around the importance of sleep. (To her point, there have been a few great pieces in  New York Times.)

One of the studies she refers to indicates that people who sleep 6 hours per night for two weeks are equally as fatigued as someone who has stayed up for 48 hours. We can also demonstrate and expand on the point visually using our FAST software (which was developed by US military to understand the effects of fatigue on performance). Arianna’s concern, is that our 24 hour world and unbalanced lifestyles are not only a detriment to our own health, but every organization’s bottom line and the economy as a whole. She is is not alone in this thinking.

According to studies, almost 30% of adult Americans are sleeping 6 hours a night or less on a regular basis. Would you expect to perform your best at work after staying up for 24 or 48 hours? Probably not. So why do people think they are able to function optimally on 6 hours of regular sleep? This is because of a natural human phenomenon known as ‘renorming’. Renorming means that we are only able  to compare how we feel today to how we felt yesterday or the day before. If someone who regularly sleeps 8 hours a night stays up for 24 hours, the deterioration of how they feel will be evident to them. If someone else decides to forgo their 8 hours per night to sleep 6 hours a night over a period of two weeks, the decline in how they feel and perform would be gradual enough that they might not even notice – But, science shows, both of these individuals will suffer similar declines in their performance and reaction time.

The FAST grid below demonstrates the performance of someone over a two week period of time who is getting 6 hours of sleep, from midnight to 6 AM. The blue arrow shows the gradual decline in performance over time.

 

fast_screen_capture_

FAST schedule grid showing performance decline over time.

 

What we are able to show using FAST software, is that by 3 PM on Monday (indicated by the black arrow) this person’s effectiveness has decreased 19%, their reaction time has decreased 24% and they are 3 times more likely to suffer an excessively long lapse in reaction time (sometimes referred to as a microsleep) than someone who is well rested.

Simply put, those who sleep only 6 hours a night, will not perform to their full potential at work and because of ‘renorming’, they won’t even realize it.

We often talk about the dangers of fatigue in the workplace for people who are working in safety sensitive operations, and the difference a small percentage drop in performance can make on an elite athlete’s game – but we can use science to demonstrate that no organization and, by association, no economy is immune to the costs associated with lost productivity caused by human fatigue.