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PRIOR SLEEP CALCULATOR FORM
BENEFITS
Worker fatigue poses a safety hazard because exhausted workers may have slowed reaction times or exercise poor judgment and thus cause safety incidents. So it’s important to take steps to address fatigue if it’s an issue in your workplace. To that end, you may need to be able to determine whether a specific worker is too fatigued to work safely at any given time.
HOW TO USE THE TOOL
Use this Prior Sleep Calculator (PSC) Form from the IPIECA, a global oil and gas association, to estimate the likely state of fatigue of a particular worker at a specific point in time. The recommendations given by the calculator must be treated with caution—it’s not an exact science and the calculated scores are no more than a guide to the likelihood of a “typical” individual being in a fatigued state.
Note: Using the calculator doesn’t take away a company’s duties to comply with the OHS law, its own OHS or fatigue management systems, and other relevant requirements for the safe management of work.
OTHER RESOURCES:
IPIECA’s Guidance on assessing risks from operator fatigue
Implement a Fatigue Risk Management System
Model Fatigue Management Policy
Fatigue Hazards Identification Checklist
Spot the Safety Violation: Time for a Cat Nap?
PRIOR SLEEP CALCULATOR FORM
WORKER’S NAME:______
DATE:______
PERSON COMPLETING FORM:______
STEP #1: Calculate worker’s recent sleep history
X (number of hours slept in the last 24 hours):______
Y (number of hours slept in the last 48 hours):______
Z (number of hours since the last sleep):______
STEP #2:Calculate the fatigue likelihood score
For every hour that Xis less than 5, add 4 points to the PSC score:______
For every hour that Yis less than 12, add 2 points to the PSC score:______
For every hour that Zexceeds Y, add 1 point to the PSC score:______
The total PSC score is the sum of the three values generated by applying these three rules:______
Refer to the table below to interpret what the PSC score may mean and to find a recommendation.
SCORE / WHAT IT MAY MEAN / RECOMMENDATION0 / Unlikely to show signs of fatigue / No action needed. Should be fit to continue working as normal.
1 or 2 / > Thinking is likely to be a bit slower
> May show minor indications of fatigue and minor mood changes / > Take simple actions to maintain alertness, such as drinking coffee, having a break, going for a walk
> Be aware of signs of fatigue
3 or 4 / May experience difficulty concentrating on complex tasks / > Avoid tasks that require sustained concentration
> Don’t start a long drive
5 or 6 / > Difficulty concentrating for long periods
> Lapses of attention likely
> May show poor judgment on complex tasks / Positive action is needed to reduce fatigue risks
7 or 8 / > Performance and/or behaviour likely to be impaired
> Difficulty sustaining attention even on simple tasks / > Apply measures to reduce the likelihood of a fatigue-induced error actually leading to an incident
> Don’t drive or work alone
> Don’t make critical decisions alone
9 or 10 / > Serious lack of energy and motivation
> Ability to perform tasks and to maintain situational awareness is likely to be seriously impaired / > Implement additional controls to prevent the potential for incident in the event that fatigue does impair performance
> Don’t drive or work alone
> Don’t make critical decisions alone
11 or more / > Difficulty staying awake at time
> Will struggle to stay focused on any task
> Short, involuntary sleep episodes (microsleeps) are likely / Probably not fit to continue working on safety-critical tasks
EXAMPLE:
Worker got 6 hours sleep in the past 24 hours
Worker got 13 hours sleep in the past 48 hours
Worker woke up at 06:00 and has been awake for 16 hours
CALCULATION:Fatigue Points
X= 60 hours below the 24-hour threshold (5)0
Y= 130 hours below the 48-hour threshold (12)0
Awake for 3 hours more than the 48-hour sleep (Y), so Z= 33
PSC Score: 3
What the score may mean:
May experience difficulty concentrating on complex tasks.
Recommendation:
Avoid tasks that require sustained concentration. Don’t start a long drive.
This tool and hundreds more available in the OHS Toolbox at . Templates and tools from OHS Insider are provided for members of our service. Members may use this document as is or as a starting point to customize their own documents. OHS Insider assumes no responsibility for the effectiveness or legality of any of its online templates or tools. Always consult your legal counsel and management before implementing any new policies or procedures.