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Suggested Citation:"Chapter 1 - Background." National Academies of Sciences, Engineering, and Medicine. 2016. Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry. Washington, DC: The National Academies Press. doi: 10.17226/21933.
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Suggested Citation:"Chapter 1 - Background." National Academies of Sciences, Engineering, and Medicine. 2016. Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry. Washington, DC: The National Academies Press. doi: 10.17226/21933.
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Suggested Citation:"Chapter 1 - Background." National Academies of Sciences, Engineering, and Medicine. 2016. Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry. Washington, DC: The National Academies Press. doi: 10.17226/21933.
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Suggested Citation:"Chapter 1 - Background." National Academies of Sciences, Engineering, and Medicine. 2016. Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry. Washington, DC: The National Academies Press. doi: 10.17226/21933.
×
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Suggested Citation:"Chapter 1 - Background." National Academies of Sciences, Engineering, and Medicine. 2016. Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry. Washington, DC: The National Academies Press. doi: 10.17226/21933.
×
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Suggested Citation:"Chapter 1 - Background." National Academies of Sciences, Engineering, and Medicine. 2016. Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry. Washington, DC: The National Academies Press. doi: 10.17226/21933.
×
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Suggested Citation:"Chapter 1 - Background." National Academies of Sciences, Engineering, and Medicine. 2016. Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry. Washington, DC: The National Academies Press. doi: 10.17226/21933.
×
Page 11
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Suggested Citation:"Chapter 1 - Background." National Academies of Sciences, Engineering, and Medicine. 2016. Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry. Washington, DC: The National Academies Press. doi: 10.17226/21933.
×
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5 1.1 Problem Statement and Research Objective Human error related to operator fatigue is a major concern in all freight operations. The gen- eral consensus is that 7 to 8 hours of sleep per 24-hour day is required to maintain acceptable levels of alertness, minimize fatigue, and permit optimum performance. A long-standing and preferred practice of crews in the U.S. tug/towboat/barge industry when two crew members must provide 24-hour on-duty coverage (e.g., captain and pilot) is to work/rest in alternating 6-hour shifts, commonly referred to as a square watch system. Each crew member has a total of 12 hours on duty with 12 hours off duty per 24 hours, and it has been customary for crew members to obtain sleep during both of their 6-hour off-duty periods. In addition, other schedules that are employed when requiring two persons to be on duty constantly over a 24-hour period have involved rectan- gular watches (e.g., 7 on: 7 off: 5 on: 5 off; 8 on: 8 off: 4 on: 4 off ) or a square watch of 12 on: 12 off. While there are no HOS regulations beyond the 15-hours-on-duty limit, 46 U.S.C. 8904(c) gives the USCG authority to establish them. The USCG (Federal Register/Vol. 76, No. 155, August 11, 2011/Proposed Rules) stated that it was considering, “requirements to increase uninterrupted sleep duration to a threshold of at least 7 consecutive hours in one of the two available off periods. . . .” Strict adherence to such requirements would ban the most common work schedule in the tug/towboat/barge industry and, in some cases, might decrease total sleep time per 24 hours. Recent laboratory data from a number of different investigators (Mollicone et al. 2007, Mollicone et al. 2008, Jackson et al. 2014, Kosmadopoulos et al. 2014, Short et al. 2014) have found that sleep can be obtained in more than one sleep period, referred to as “anchor-sleep/ nap-sleep,” and that as long as the total duration is 7 to 8 hours, performance is comparable between a single sleep period and two separate sleep periods. Therefore, it is important to determine the impact of an anchor-sleep/nap-sleep strategy in the inland waterway setting. To aid in the optimization of such strategies, it is also important to assess the implementation by personnel of existing educational materials, such as the USCG Crew Endurance Management Practices and tug/towboat/barge industry materials. The objective of this research is to develop a compendium of best practices for enhancing sleep efficiency on towboats in the U.S. tug/towboat/barge industry. 1.2 Previous Research 1.2.1 Sleep and Circadian Rhythms The basic need or drive to sleep is a biological imperative, just as is the need for food, water, and oxygen. The sleep-wake cycle is regulated by two fundamental processes that are referred to as the homeostatic process and the circadian process. The scientific basis for these two processes Background C H A P T E R 1

6 Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry is described below, as are some of the fundamental aspects and characteristics of the sleep-wake cycle. In addition, the behavioral and physiological consequences of sleep deprivation, as well as the consequences of sleeping or being awake at the wrong times of the circadian day, are also described. 1.2.2 Homeostatic Process Regulating the Drive to Sleep This process refers to the fact that the longer one is awake, the greater the drive to sleep, i.e., the pressure to sleep becomes greater. This process is usually measured in humans by the amplitude of the delta waves in an electroencephalogram (EEG)—a measure of brain wave activity during non-rapid eye movement sleep. Thus, the longer one is awake, the harder it is to stay awake. 1.2.3 Circadian Process It has been firmly established that a circadian (about 24 hours) clock in the brain regulates the sleep-wake cycle, as well as all 24-hour physiological and behavioral rhythms in mammals. The master circadian clock is located in the anterior hypothalamus, within two small nuclei referred to as the suprachiasmatic nucleus (SCN). For most people living on a normal day-night schedule, the low point (nadir) of alertness is between 03:00 to 07:00, which is also the time of the mini- mum of body temperature and when melatonin levels are elevated, two factors that contribute to the circadian drive to sleep. The 24-hour rhythm in sleepiness also reaches its maximum (to be asleep) at around 03:00 to 07:00. This low point in alertness, and maximum drive to sleep, coin- cides with when most accidents that are caused by fatigue occur in the transportation industry. The master circadian clock in the SCN regulates not only the 24-hour rhythms in the sleep-wake cycle and alertness, but also 24-hour rhythms in human performance and cognitive abilities, as well as all behavioral and physiological rhythms. 1.2.4 Cannot Override the Need to Sleep While there is some belief that one can remain alert even when very tired by having the will power, the “right stuff ” (i.e., the “Iron Man Syndrome”), this is not the case, and sleep can over- whelm even the strongest willed, most highly motivated person trying to stay awake. An extremely tired individual can fall uncontrollably into a microsleep, lasting only a few seconds, or into a full state of sleep, in which a total loss of function occurs—even while driving a car, truck, train, or while piloting a ship. 1.2.5 Timing of Sleep Just as it is difficult to stay awake between 03:00 and 07:00, it is also difficult to fall asleep dur- ing the daytime for individuals living on a normal 24-hour light-dark cycle (Kryger et al. 2005). Individuals who work at night and attempt to sleep during the day are often only able to obtain 4 to 6 hours of sleep; the average person needs about 7.5 to 8 hours of sleep per 24-hour day to be fully rested and alert for the next day’s activities [Office of Technology Assessment (OTA) 1991]. In addition, daytime sleep is less efficient and less recuperative than nighttime sleep is for many internal and external reasons (Monk 2005). When sleep is out of phase with the circadian clock, the sleep episode is shorter since the clock is telling the body and mind to be awake (Kryger et al. 2005). Furthermore, daytime environmental factors, including light, noise, and temperature make it more difficult to sleep during the day. Workers that routinely sleep during the day will have poorer sleep quality, leaving them less refreshed for work activities at night. The effects can be cumulative when individuals repeatedly attempt to sleep during the day, at a time their circadian clock is telling them to be awake (Van Dongen et al. 2003).

Background 7 1.2.6 Duration of Sleep The average human needs about 7.5 to 8 hours of sleep per night to be fully refreshed. Even a small reduction in sleep time, for example, from 8 hours to 6 hours, can impair performance [Carskadon and Dement 1981, Carskadon and Dement 1982, National Transportation Safety Board (NTSB) 1999, Van Dongen et al. 2003)]. 1.2.7 Importance of Regularity of Timing of Sleep Irregularity of the sleep-wake schedule means people are sleeping (and working) at different times of the day and night, often for multiple days in a row. The circadian system does not adjust instantly or even rapidly to a change in the sleep-wake schedule (Takahashi et al. 2001, Kryger et al. 2005). Indeed, it may take 5 to 7 days to re-adjust to a new fixed work-rest schedule, but if that schedule is constantly changing, it may never re-adjust, i.e., the worker is in a constant state of “jet lag.” 1.2.8 Cumulative Effects of Sleep Restriction It has been known for 25 years that alertness levels gradually decrease day after day if indi- viduals repeatedly do not obtain sufficient sleep. For example, in one early study, alertness levels gradually were reduced each consecutive day when sleep was reduced to 4 to 5 hours per night over a 7-day period (Carskadon and Dement 1981, NTSB 1999). Quantitative studies have been carried out demonstrating that chronic sleep restriction to 4 to 6 hours per night over a 14-day period leads to cumulative, dose-dependent deficits in cognitive performance on a variety of dif- ferent measures of cognitive ability. Indeed, for some measures of behavior, the adverse effects on performance of cumulative sleep loss in people sleeping 4 to 6 hours per night were similar to those observed in subjects totally sleep deprived for 24 or 48 hours (Van Dongen et al. 2003). Interestingly, sleepiness ratings for many of the subjects indicated they were largely unaware of their increasing cognitive deficits, which may explain why individuals who are in a chronic state of sleep deprivation think they can perform well. Their tiredness itself prevents them from recognizing their deficits in performance. 1.2.9 Adverse Effects of Fatigue and Disrupted Circadian Rhythms on Safety, Performance, Cognitive Abilities, and Ability to Operate Motorized Vehicles Sleep and sleepiness are amongst the most basic of human behaviors (Mitler et al. 1997). While technological advances have eliminated many sources of accidents, sleep deprivation and fatigue continue to be a major cause of error and accidents in modern society. A study in Great Britain estimated that 27% of drivers who lost consciousness behind the wheel fell asleep, as opposed to fainting, having a seizure, or having a heart attack. However, this 27% accounted for 83% of the fatalities. Other investigators have also observed a high rate of fatality in sleep-related accidents. The increased fatality rate is probably due to the tendency for sleepy drivers to push on rather than stop and sleep, thereby allowing for unintended bouts of sleep to occur without warning. Once a driver has fallen asleep, there is little or no attempt to brake or otherwise avoid a collision (Mitler et al. 2000). There is extensive literature going back many years demonstrating that prolonged wakeful- ness and/or the lack of sufficient sleep can lead to severe decrements in cognitive performance [for reviews see OTA (1991), Dinges (1995), Zee and Turek (1999), Harrison and Horne (2000)]. Particular attention has been paid to studies on the effects of prolonged periods of wakeful- ness and/or lack of sufficient sleep in the transportation industry due to the life-threatening

8 Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry aspects associated with fatigue and accidents in transportation operations, including the ship- ping, trucking, airline and railroad industries (Mitler et al. 1997, NTSB 1999, Lamond et al. 2001, Lamond et al. 2004). As noted below in the consensus statement published in Sleep Research: (Akerstedt 2000): It is the consensus of an international group of scientists who study human performance, safety, and pre- vention of accidents associated with work schedules, night activity, and inadequate sleep that: 1. The 24-hour society, with around the clock operational demands in all transportation modes, challenges the powerful and vital need for sleep. Sleep, alertness, and performance are fundamentally linked to the 24-hour biological clock. 2. The major causes of fatigue are (a) the time of day of the transport operation (e.g., night/early morning), (b) a long duration of wakefulness, (c) inadequate sleep, (d) pathological sleepiness (sleep apnea, etc.), (e) prolonged work hours (not necessarily operating the vehicle). 3. Fatigue (sleepiness, tiredness) is the largest identifiable and preventable cause of accidents in transport operations (between 15% and 20% of all accidents), surpassing that of alcohol or drug related incidents in all modes of transportation. Official statistics often underestimate this contribution. 4. Under-estimation of the impact of fatigue can lead to the underutilization of important countermeasures. 5. Public and environmental safety, health, and productivity are compromised by fatigue and sleepiness, with substantial financial costs to individuals and society. 6. Fatigue-related risk may be reduced through a variety of interventions, that include education (about sleep, the biological clock, sleep disorders, fatigue countermeasures), improved scheduling of work hours, and the judicial use of strategies and technologies. Fatigue is recognized as an important cause of accidents. The consensus report cited above, written by a number of sleep researchers/experts, concluded that sleep loss and circadian influ- ences are determinants of performance-related incidents and accidents, and are likely to compro- mise public safety. The critical importance for managing fatigue in the transportation industry led to the May 1999 NTSB Safety Report (SR) (NTSB/SR 99-01) titled, “Evaluation of U.S. Department of Transportation Efforts in the 1990s to Address Operator Fatigue” (NTSB 1999). • This NTSB report was a follow-up to a 1989 NTSB-SR that made three specific recommenda- tions to the U.S.DOT: the third one being that all the transportation modes upgrade their gov- erning HOS regulations to be consistent with the latest research on fatigue and sleep issues. • The NTSB sponsored a watershed meeting in 1995 attended by more than 500 people from all modes of transportation on “fatigue” in the transportation industry. • In 1999, the NTSB gave the USCG 2 years to come up with new “scientifically based hours- of-service regulations that set limits on hours of service and provide predictable work and rest schedules and consider circadian rhythms and human sleep and rest requirements” (NTSB 1999). In addition to falling asleep while operating a motorized vehicle, sleep loss is associated with severe effects on cognitive performance and decision-making capabilities (Mitler et al. 1997, Philip et al. 2003). Sleepiness or fatigue can cause impaired reaction time, impaired judgment, impaired vision, problems with information processing, short-term memory loss, decreased mental and physical performance, loss of vigilance and loss of motivation (Dinges 1995, Harrison and Horne 2000). Indeed, impairments to the mental state associated with fatigue can be as severe, and even more severe, than being intoxicated (Dawson and Reid 1997). 1.2.10 Fatigue, Sleep, and Disrupted Circadian Rhythms in Marine Operations Although not as extensive as for other industries (e.g., trucking and railroad), there have now been a number of studies documenting the impact of various work schedules on fatigue and performance in mariners in different environments (e.g., open sea vs. inland waterways). While some studies have been short term (e.g., a few days) in nature and others long term (e.g.,

Background 9 a few weeks), and different studies have utilized different outcome measurements (e.g., subjec- tive sleepiness, performance-based tests), almost all have reported adverse effects on crew sleep and/or performance that depend on length on duty and/or time of day on duty (or sleep time). It should be noted that the problems associated with “shift work,” and the need to maintain 24/7 operations are not unique to the marine industry, as there is extensive literature on the adverse effects of 24/7 scheduling in other transportation industries (e.g., air, rail, trucking) on health, safety, and productivity. Between industries and within industries the operational demands are of tremendous complexity and diversity and the solutions are also not a simple “one size fits all.” Therefore, the solutions for alleviating fatigue and decreased cognitive abilities due to sleep and circadian based problems associated with obtaining sufficient and quality sleep need to be addressed by using an integrated global approach as initially outlined in the Crew Endurance Management Practices: A Guide for Maritime Operations (Comperatore and Rivera 2003) report. 1.2.11 Napping Strategies to Reduce Fatigue It is difficult to generalize the results from the “napping” literature because the design of such studies, the purpose of the studies, and the outcome measurements vary greatly between them, making it impossible to provide simple conclusions. Nevertheless, certain overall con- clusions do emerge from both laboratory and field-based studies of various napping strategies, including: • Naps (defined as being a period of sleep < 50% of main sleep period, or “anchor sleep”) can be beneficial for reducing fatigue and improving performance, especially for individuals under restricted (voluntary or involuntary) anchor sleep, or when the nap is taken before or during a time the individual is attempting to work/be awake while their internal biological clock is attempting to induce sleep. • Almost all initial studies examined the effects of short naps (10 to 60 minutes) by using various performance measurements over the next few hours (e.g., 30 minutes to 3 hours) following the nap. Most studies are short term in nature (1 day) and have addressed the immediate effective- ness of the nap on performance capabilities, not on long-term benefits of naps in conjunction with a fixed anchor-sleep time. • Although many studies have been carried out to determine if and what kind of nap can improve acute performance in a sleepy or circadian-disrupted individual, surprisingly, until recently, the literature is almost silent on the question: How can one combine a regularly scheduled nap with regularly scheduled anchor sleep to minimize fatigue and maximize performance under chronic conditions? However, recent research has collectively come to the same conclusion: The beneficial effects of sleep on fatigue and performance are mostly dependent on the total amount of sleep achieved over any 24-hour period, and are not dependent on the consolida- tion of sleep into a single bout (Mollicone et al. 2007, Mollicone et al. 2008, Jackson et al. 2014, Kosmadopoulos et al. 2014, Short et al. 2014). Therefore, the key to any schedule for sleep and wake activities is to design the schedule so the individual can obtain 7 to 7.5 hours of sleep per 24 hours regardless of the timing of the sleep-work schedule. 1.3 Findings from Prior Research That This NCFRP Research Builds On From 2007–2012, investigators have carried out research in the tug/towboat/barge industry (Preuss et al. 2010, Reid et al. 2012, Reid et al. 2013). As part of this work they interacted with hundreds of crew members on vessels from over 30 inland waterway companies to assess and quantify the amount of sleep the crews are obtaining on a two-watch system, as well as their levels of fatigue and overall health. This research enabled the research team to collect an unprecedented

10 Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry amount of data about the sleep habits and strategies of crew members attempting to obtain sufficient sleep while on the 6:6:6:6 square watch schedule for prolonged periods of time (e.g., 14 to 28 days), as well as their sleep and wake habits when off duty. Also collected were real-world data on fatigue, stress, health indices, and barriers to obtaining good sleep while on the vessel. Educational material was also distributed to 163 wheelhouse crew members. Together, these data allowed for research to determine what are the behaviors and characteristics of indi- viduals that make up the best practices used by the “good sleepers,” as well as the compen- dium of behaviors and characteristics of crew members who are not obtaining adequate sleep. The researchers have also been able to analyze the environmental factors that impact sleep-wake behaviors of crew members on board the vessel and in their home environments. These data enabled the development of models that will guide tug/towboat/barge operators and their crews to implement best practices on board vessels in the U.S. tug/towboat/barge industry, as well as in other industries (e.g., trucking) where sleep is often split into what is referred to as “anchor sleep/nap sleep” over a 24-hour period. It should be noted that modern society’s propensity to sleep during a single 8-hour period is a relatively recent phenomenon. There is historical evidence that sleep occurred in two sleep bouts, referred to as first and second sleep (Ekirch 2006), and there is evidence from modern clinical studies where humans lived for up to 30 days on a 10-hour light/14-hour dark day, that they also split sleep into two periods (Wehr et al. 1993). A major goal of this research was to understand and implement best practices that will allow tug/towboat/barge crews to obtain 7 to 8 hours of sleep split into two sleep periods while on a 6:6:6:6 square watch. The results from previous work on board towboats and with crew members while on duty and in the home envi- ronment, when taken together with data in the literature, especially data on the effects of split- sleep on fatigue and performance, have enabled the researchers to provide clear suggestions to improve current practices across the industry. The results of these studies have allowed the devel- opment of strategies for obtaining sufficient sleep on board tug/towboat/barge vessels that can now be implemented with and communicated to other stakeholders, including operators, crews, the USCG, and the NTSB. It is expected that the development of best practices strategies and educational materials will increase sleep and reduce human errors due to fatigue not only for crews on tugs/towboats/barges, but also in other industries that require the use of an anchor- sleep/nap-sleep strategy to maintain alertness and minimize fatigue during on-duty operations for individuals in 24/7 work environments. Many of the best practices suggested have already been implemented by a number of companies in the tug/towboat/barge industry, especially those that involve maximizing the environmental conditions that allow crew members to sleep efficiently; however, implementing the totality of the best practice suggestions will require that all stakeholders interact and work together so that recognition of the importance of sleep for safety and performance becomes part of the everyday culture of the entire industry. Before starting work on this research, the research team completed four phases of research related to fatigue and sleep in crew members on tugs/towboat/sbarges. For Phase I, a white paper was prepared that provided a detailed analysis of published studies and data on schedules and fatigue levels of crew members on board vessels throughout the maritime industry (i.e., blue/open water, as well as inland waterways, where vessels must be maintained 24/7). Since it was apparent that the scheduled duty times in the maritime industry were often split into 2 periods of work over 24 hours (and thus, 2 periods of rest per 24 hours) in order to maintain vessel activities 24/7, the Phase I white paper also included an analysis of the scientific literature on the use of naps in association with anchor sleep (i.e., a split-sleep schedule) for reducing fatigue and optimizing performance. The conclusion from this analysis was that any viable strategy for an industry that has two crew members who must be on duty collectively for 24 hours over many days (i.e., crew members must be on duty and maintain high levels of vigilance for a total of 12 hours each 24-hour day) would require anchor-sleep/nap-sleep strategies to manage fatigue and reduce risk on towing vessels.

Background 11 This white paper led to the design of a Phase II study with the objective of developing a better understanding of the sleep-wake schedules and sleep amount of the crew members on board towing vessels that were using a 6 on: 6 off: 6 on: 6 off duty schedule. The Phase II proposal was developed after the research team rode on two towboat vessels to obtain first-hand exploratory information on the lives of crew members in the barge industry. For the Phase II research, investigators rode on five towing vessels in 2009 and collected sleep-wake data on crew mem- bers. This work was supported by seven different towing vessel companies (Marathon, K-Sea, Canal Barge, Ingram Barge, American Commercial Lines, Kirby, and the Cenac Towing Co). In 2010, with support from the American Waterway Operators (AWO), the researchers carried out a Phase III study that collected sleep time and sleep duration data from crews on ten different towing vessels. The findings from these two studies were consistent and gave a clear understand- ing of (1) how many hours crew members actually spent in bed during each of the 6-hour sleep opportunities and (2) how much sleep time (based on wrist actigraphy data) they were actually obtaining. Findings from these two studies consistently indicate that while wheelhouse crew members appear to be spending an adequate time in bed each day (e.g., approximately 8 hours), they are not able to obtain more than about 6.5 hours of sleep per 24 hours (Preuss et al. 2010). A strength of the Phase II and Phase III studies was the use of objective measures to determine sleep-wake times; however, given the resources available, it was not possible to study a large num- ber of crew members over an extended period of time. Therefore, in the Phase IV studies (also supported by the AWO), online technologies were used that enabled the tracking of the sleep- wake behaviors of over 160 wheelhouse crew members (captains and pilots) for extended periods of time when on duty on a 6:6:6:6 square watch, as well as in their home environments. Crew on the front watch typically work between the hours of 06:00 to 12:00 and 18:00 to 24:00, while crew on the back watch typically work between the hours of 24:00 to 06:00 and 12:00 to 18:00, with rest intervals in the intervening periods. Previous studies indicated that there was no differ- ence in the sleep duration of crews on the front (captains) and back (pilots) watches. This was unexpected as the front watch crew had a rest period during the night (24:00 to 06:00) when the circadian clock is signaling the body to sleep, and as such, it should be the best time to sleep. The rationale for studying only the wheelhouse crew members in Phase IV was that given the small number of wheelhouse crews previously studied (19 in Phases II and III), it was difficult to identify factors that may be impacting sleep in these wheelhouse crews. The major aims of the Phase IV studies were (1) to determine and compare the sleep patterns of wheelhouse crews both when on extended vessel duty (21 to 28 days) as well as when at home for an extended period of time and (2) to use online technologies to identify factors that may be influencing sleep quality in a large number of wheelhouse crew members. An additional aspect of this study was to take the opportunity to disseminate the education materials developed during the Phase III studies to a much larger number of crew members and, at a later time, to carry out follow-up assessments to determine the effectiveness of these educational materials (this research). As part of the Phase IV online studies, the researchers also obtained data on height and body weight in order to calculate body mass index (BMI) and collected a variety of measures of sleep and fatigue levels using a number of scientifically validated tests and questionnaires (Reid et al. 2013). 1.4 Scope of NCFRP Research The overall approach for the NCFRP research involved: 1. An assessment of the use of split-sleep or anchor-sleep/nap-sleep strategies in the U.S. tug/ towboat/barge industry for crew working on a 6:6:6:6 square watch schedule. 2. An assessment of whether there were any changes in behavior in crew members following their participation in the Phase IV study and after dissemination of the previously developed educational materials.

12 Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry 3. The identification of those groups of individuals who did or did not change their sleep-wake behaviors and to what degree and why. 4. The identification of the multivariate factors that enable some crew members to obtain ade- quate sleep (7 to 8 hours) per 24 hours and the factors that are associated with not obtaining sufficient sleep (<6.5 hours) per 24 hours. 5. The identification of best practices across other transportation industries (e.g., railroad, trucking, and aviation) for enabling individuals on unusual shift work schedules to obtain adequate and efficient sleep to develop models that could be used to advise supervisors and crews in their development of a fatigue management program that could be incorporated in their overall SMS. 6. To integrate the information obtained into a compendium of best practice. The results from the NCFRP research, along with data in the literature and the collection of information on best practices from other transportation industry leaders, have led to proposed guidelines and best practices for obtaining sufficient sleep while on towing vessels to enhance safety and performance. Since a majority of the industry utilizes schedules that have crews work- ing two shifts per 24 hours, the researchers have focused much of the work and best practices for crews who need to develop effective split-sleep or anchor sleep and nap-sleep strategies. It should be noted that research in the laboratory or field clearly indicates that individuals cannot obtain 7 to 8 hours of uninterrupted sleep when working a 6:6:6:6 square watch or 7:7:5:5/8:8:4:4 rectangular watches, especially when sleep is attempted at the wake phase of the circadian clock. Therefore, whether crews are on the square or rectangular watches, they will need to develop an anchor-sleep/nap-sleep strategy. While crews on a 12:12 watch might be able to obtain 7 to 8 hours of uninterrupted sleep when the sleep period is during the normal nighttime hours, it may not be possible when sleeping during the daytime. In addition, for many demanding jobs, such as operating towboats, 12 hours on duty may be too demanding of a work period, especially when the 12 hours on duty occur during the normal sleep time. In addition to proposing best practices, this research, as well as the research of others and previous work by this research team within the tug/towboat/barge industry, has enabled the research team to propose an implemen- tation plan that will involve working collectively between the major stakeholders, including tug/towboat/barge management and operators, crews, relevant trade organizations, such as the AWO, and key federal agencies, especially the USCG and the NTSB.

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TRB's National Cooperative Freight Research Program (NCFRP) Report 36: Enhancing Sleep Efficiency on Vessels in the Tug/Towboat/Barge Industry provides best practices to improve an operator's sleep and reduce operator fatigue in the United States inland waterway industry, including the use of anchor-sleep/nap-sleep strategies.

NCFRP Report 36 identifies and describes the metrics that could be used to evaluate current operational interventions (e.g., educational materials and programs; noise abatement; sleep disorders screening, especially sleep apnea; wellness and nutritional programs) for their effectiveness in improving sleep efficiency on tugs/towboats/barges; evaluates the use of anchor-sleep/nap-sleep strategies on sleep behavior among personnel in the inland waterway industry; and identifies barriers that inhibit waterway personnel from adopting good sleep management practices and propose ways to overcome the barriers.

The report also develops a list of best practices that could be implemented by the waterway industry, companies, crews, or individuals to enhance sleep efficiency; and includes a compendium of best practices for enhancing sleep efficiency in the U.S. inland waterway industry.

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