Managing fatigue: It’s about sleep - PACDEFF

1 THEORETICAL REVIEWM anaging fatigue : It s about sleepDrew Dawson*, Kirsty McCullochCentre for sleep Research, University of South Australia, Basil Hetzel Institute,The Queen Elizabeth Hospital, Woodville Road, Woodville, SA 5011, AustraliaKEYWORDSF atigue;Prior sleep ;Wakefulness;Safety;Management;Pres criptive rules;Hours of serviceSummaryFatigue has increasingly been viewed by society as a safety has lead to increased regulation of fatigue by governments. The most commoncontrol process has been compliance with prescriptive hours of service (HOS) rulesets. Despite the frequent use of prescriptive rule sets, there is an emergingconsensus that they are an ineffective hazard control, based on poor scientificdefensibility and lack of operational flexibility. In exploring potential alternatives,we propose a shift from prescriptive HOS limitations toward a broader Safetymanagement system (SMS) approach.

2 Rather than limiting HOS, this approachprovides multiple layers of defence, whereby fatigue -related incidents are the finallayer of many in an error review presents a conceptual basis for Managing the first two levels of an errortrajectory for fatigue . The concept is based upon a prior sleep /wake model, whichdetermines fatigue -risk thresholds by the amount of sleep individuals have acquiredin the prior 24 and 48 h. In doing so, Managing level 1 of the error trajectory involvesthe implementation of systems that determine probabilistic sleep opportunity, suchas prescriptive HOS rules or fatigue modelling. Managing level 2, requires individualsto be responsible for monitoring their own prior sleep and wake to determineindividual fitness for duty. Existing subjective, neurobehavioral and electrophysio-logical research is reviewed to make preliminary recommendations for sleep andwake thresholds.

3 However, given the lack of task- and industry-specific data, anydefinitive conclusions will rely in post-implementation research to refine Elsevier Ltd. All rights fatigue associated with working conditionshas been identified as a major occupational healthand safety (OH & S) risk in most developed part, this has been driven by scientific evidence,indicating an association between increasing fati-gue and decrements in cognitive function,1,2impaired performance,3,4increasing error rates5,6and ultimately, reduced ,8 Accordingly,governments and safety professionals have arguedthat mental fatigue is an identifiable work placehazard that warrants regulatory , efforts in fatigue -risk managementhave attempted to reduce fatigue -related riskthrough compliance with an agreed set of rulesgoverning hours of work. In the US, these aregenerally referred to as hours of service (HOS) sleep Medicine Reviews (2005)9, 365 $ - see front matterQ2005 Elsevier Ltd.

4 All *Corresponding author. Tel.:C61 88 222 6624; fax:C61 (D. (K. McCulloch).rules. At the most fundamental level, regulationhas involved the prescription of maximum shift andminimum break durations for individual shifts orwork periods. In addition, some industries andorganizations have supplemented individual shiftrules with supra-shift rules that further restrict thetotal number of sequential shifts or cumulativehours worked in a given period ( week, month oryear).9,10 These limitations have typically beenimposed coercively via a regulatory body or voluntarily through a labor ,12 The traditional prescriptive HOS approach mostprobably derives from earlier regulatory models formanaging physical rather than mental fatigue . Inthe early part of the 20th century, OH&S hazardsrelated to physical fatigue were managed primarilyby regulating the duration of work and non-workperiods.)

5 Previous research had indicated thatphysical fatigue accumulates and discharges in abroadly monotonic manner with respect to such, Managing physical fatigue by limiting workhours and break periods was both scientificallydefensible and operationally the application of prescriptive duty limi-tations may have been an appropriate control forphysical fatigue , we do not believe the same can beassumed for mental fatigue . It is common to useanalogous approaches for the regulation of a newhazard. However, in the case of mental fatigue , thisapproach incorrectly assumes that the determi-nants of mental fatigue are similar to those forphysical it is true that mentalfatigue does, in part, accumulate in a relativelylinear manner,15there are significant additionalnonlinearities driving the dynamics of fatigue andrecovery processes for mental biology, for example, influences thedynamics of fatigue accumulation and recovery in away that produces significant , prescriptive limitations on shift durationgenerally assume that a break of a given length hasa uniform recovery value with respect to mentalfatigue.

6 While this may be relatively true withrespect to physical fatigue , it is demonstrably notthe case with respect to mental fatigue . Indeed,providing the same length of time off during thesubjective day, as opposed to subjective night, willresult in a significantly reduced amount of our opinion, estimating the level of mentalfatigue associated with a given pattern of work islinked more to the timing and duration of sleep andwake within the break, rather than the duration ofthe break alone. Although, there is clear scientificevidence to support this notion, few regulatorymodels acknowledge it explicitly. As depicted inFig. 1, it is our view that regulatory models basedonly on shift duration are unlikely to producecongruence between what is safe and what ispermitted and what is unsafe and not relationship between the recovery value ofnon-work periods (vis-a`-vis mental fatigue ) and theactual amount of sleep obtained has becomeincreasingly complex in recent years.

7 In additionto the biological limitations of this approach,increases in total working hours, lengthening ofshift durations from 8 to 12 h, and concomitantreductions in breaks from 16 to 12 h18havesignificantly restricted the opportunity for , changes in workforce demographicsand the social use of time in and outside thePermittedNot SafeSafeNot PermittedFigure 1 Depicts the types of control involved withmost regulatory models. Effective models should providecongruence between what is safe, and permitted as wellas what is unsafe, and not permitted. This is often not thereality with traditional prescriptive HOS for the purposes of this review all referencesto fatigue imply mental fatigue unlessspecifically indicated otherwiseFREfatigue-related errorFRIfatigue-related incidentFRMS fatigue risk management systemHOShours of serviceOH&S occupational health and safetyOHSAS occupational health and safety manage-ment systemsPSWM prior sleep /wake modelSMSsafety management systemD.

8 Dawson, K. McCulloch366workplace have exerted additional downwardpressure on the amount of time individuals chooseto allocate for trends in fatigue managementAs outlined above, many traditional approaches tofatigue management have focused on hours-of-service. However, these approaches may be oflimited value in the systematic management offatigue-related risk. This has been particularlyhighlighted by recent research and policy initiativesin the US,11 Australia,20 22 Canada23and ,25In these jurisdictions, there is anemerging, albeit controversial, view that we mightmore usefully explore alternatives to prescriptivemodels of fatigue management. Moreover, relativeto traditional prescriptive approaches, alternativeapproaches may hold significant potential forimproved safety and greater operational date, most alternative approaches to pre-scriptive HOS embed fatigue management withinthe general context of a Safety Management System(SMS)

9 And arguably provide a more defensibleconceptual and scientific basis for Managing fati-gue-related risk as well as the potential for greateroperational ,27 This is in marked con-trast to current HOS models whose roots areinextricably bound up in the history of their laborrelations process where the primacy of short-termfinancial factors has frequently distorted ,29 Despite the theoretical attraction of alternativeSMS based approaches to prescriptive HOS, manycommentators have, with good reason, expressedreservations about their actual benefits in example, an increase in the flexibility of HOSregulation has often been interpreted (by employ-ees and their representatives) as a disingenuousattempt to deregulate or subvert current orproposed HOS rules. Conversely, tightening of HOSregulation to reduce fatigue has sometimes beeninterpreted (by employer groups and their advo-cates) as a disingenuous attempt to leverage betterpay and conditions, rather than improve the last few years, our research group hasconducted extensive consultation with industrystakeholders and regulators in several countriesand in a variety of industries, to understand howfatigue might best be managed using alternativeapproaches.

10 In doing so, we have canvassed twobroad approaches. First, the modification of tra-ditional prescriptive HOS regulations to ensure theyaddress matters related to legal and scientificdefensibility as well as operational , we have considered alternative regulatorymodels that might be used as the basis of a newapproach that meets the previously mentionedgoals of scientific defensibility and objective was to establish a well-structuredview of how fatigue might best be regulated, as wellas the most appropriate way in which such reformmight be achieved at the practical the basis of discussions with industry, webelieve there is an emerging consensual view that: Given the diversity of modern organizationalpractice, a traditional prescriptive HOS approachmay not be the most appropriate or only way tomanage fatigue -related risk.