I am past the point of being dangerous by the time I realize it. My vision has been blurry for the past twenty miles and I can feel my brain shutting down.
Jesus, did I just fall asleep driving?
I’m not sure, there seems to be a second or two of consciousness missing but we are still on the road so I don’t know. Even though we are just ten miles from the station on a return trip from a midnight transfer I throw in the towel and ask my partner “can you drive?”
We have known for some time that what we were doing was probably on the edge of safe with regards to fatigue management. I started a project at work to examine the evidence that was out there and try to come up with an actual evidence based answer as to how many hours can one work without sleep before driving becomes dangerous and an answer to the question how much sleep is needed before you are safe to drive again.
I am sharing my summary of data here so that if anyone wants to make a fatigue risk management system (FRMS) for their agency they can use some of the data I have scraped together.
The TL;DR version: 18 hours awake and on duty and you should not be driving. If you work for a service that does 48 hour shifts you should have at least 6 hours of uninterrupted sleep (maybe more) before driving after being on duty for 18 hours.
Rationale for the 18-hour cut-off: Studies have demonstrated that the effects of sleep deprivation can be equated with driving while impaired due to alcohol. Multiple studies have demonstrated that after prolonged sleep deprivation drivers function at the same level as a driver that is at, or worse than, the legal limit for alcohol consumption
- A 2000 study demonstrated driving performance equivalent to a BAC of 0.1% occurred after between 17.74 and 19.65 hours of wakefulness (Williamson and Feyer, 2000).
- A 1997 study assessing hand-eye coordination demonstrated that after 17 hours of continual wakefulness subjects performed at the same level as having a BAC of 0.05% and after 24 hours awake they performed at the same level as having a BAC of 0.10% (Dawson and Reid, 1997).
- A 2001 study attempted to correlate driving with a lack of sleep to driving performance while under the influence of alcohol. The results showed that mean tracking, tracking variability, and speed variability 18.5 and 21 h of wakefulness produced changes of the same magnitude as 0.05 and 0.08% blood alcohol concentration, respectively (Arnedt 2001).
Rationale for the 6-hours of uninterrupted sleep requirement: In December of 2016 the American Automobile Association Foundation for Traffic Safety released a study which looked at 4,571 crashes between July of 2005 and December of 2007 (see table 1). The data speaks for itself as to the increased risk of an automobile crash with decreased sleep in the past 24 hours.
|(table 1) Effects of acute sleep deprivation on accident risk|
|Total hours of sleep in the past 24 hours||Crash rate compared to drivers who get 7+ hours of sleep|
|4 – 4:59||4.3|
|5 – 5:59||1.9|
|6 – 6:59||1.3|
|Source: Teft, B, Acute Sleep Deprivation and Risk of Motor Vehicle Crash Involvement. AAA Foundation for Traffic Safety|
The National Highway Traffic Safety Administration (NHTSA) officially announced a new joint initiative with the National Association of State EMS Officials (NASEMSO) to develop voluntary, evidence based fatigue risk management guidelines for EMS agencies. The guidelines are expected to be released later in 2017 or in 2018 and will be available at www.emsfatigue.org . In the meantime, it may be relevant to examine other industries that have a fatigue risk management system in place for comparison (see table 2).
|(table 2) Other industries with a Fatigue Risk Management System|
|Federal Motor Carrier Safety Administration||Passenger carriers: Max of 15 hours on duty time|
|Federal Motor Carrier Safety Administration||Property carriers: Max of 14 hours on duty|
|Federal Motor Carrier Safety Administration||Short haul exemption: max of 16 hours on duty|
|FAA / Airlines||Max duty period: 14 hours (max flight time is 8 hours)|
|Federal Railway administration||Max duty period of 12 hours|
CFR › Title 46 › Chapter I › Subchapter B › Part 15 › Subpart J › Section 15.1111
|Required 10 hours rest per 24 hour period with no work interval exceeding 14 hours.|
It will be interesting to see where the NHTSA guidelines land and what, if any, changes occur in the industry.
- Williamson A, Feyer A. Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication. Occupational and Environmental Medicine. 2000;57(10):649-655. doi:10.1136/oem.57.10.649.
- Dawson D, Reid K. Fatigue, alcohol and performance impairment. Nature. 1997;388(6639):235.
- Arnedt JT, Wilde GJ, Munt PW, Maclean AW. How do prolonged wakefulness and alcohol compare in the decrements they produce on a simulated driving task?. Accid Anal Prev. 2001;33(3):337-44.
- Teft, B, Acute Sleep Deprivation and Risk of Motor Vehicle Crash Involvement. AAA Foundation for Traffic Safety
- Federal Motor Carrier Safety Administration hours of service regulations, available at https://www.fmcsa.dot.gov/regulations/hours-service/summary-hours-service-regulations
- FAA regulations available at https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=13273
- Federal Railway Administration technical bulletin, September 2014. Available at https://www.fra.dot.gov/eLib/details/L15919#p1_z50_gD_lCT_kHours%20of%20Service
- Code of Federal Regulations, available at https://www.gpo.gov/fdsys/pkg/CFR-2002-title46-vol1/xml/CFR-2002-title46-vol1-sec15-1111.xml