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65 CHAPTER EIGHT SYNTHESIS CONCLUSIONS AND DISCUSSION INTRODUCTION here is intended to provide important information to aid in the understanding of: Throughout this synthesis report there are numerous assess- ment statements, conclusions, discussion, and some identified 1. The state of scientific knowledge from published needs for subsequent research. This chapter is a summary of research findings regarding the health and performance key points and provides suggestions for logical steps to follow effects of numerous chemical substances that sometimes from this work. are ingested by commercial drivers; 2. Findings and practices relating to which psychoactive chemicals offer promise to commercial drivers striving FINDINGS FROM THE LITERATURE REVIEW to sustain alertness and to manage driver drowsiness or One of the primary goals of the synthesis was to identify and fatigue during partial sleep deprivation, which is so often elaborate on published research regarding the many psycho- necessitated by extended freight delivery operations; and active chemical substances that drivers use. In particular, 3. What the literature and practice indicate to be acceptable the synthesis team was in quest of information on psycho- sleep aids for use by commercial drivers in managing active chemical compounds that might play a feasible role in their sleep schedules during on-the-road operations, sustaining driver alertness or promoting sleep, and therefore including at times of the day when it is not normally would assist in management of commercial driver fatigue. conducive to sleep. Although the literature review here does identify several chemical substances that may serve those purposes, this syn- The comprehensive literature review reports numerous thesis does not propose, nor prescribe specific usage protocols laboratory experimental studies of the performance of indi- for any chemical substance described. Rather, it provides a viduals under the influence of many psychoactive chemical reporting of the highlights of many research studies cited in substances. Some of those chemicals (medications, drugs, etc.) the scientific literature, with a special focus on identifying those have been safely used in various sustained work settings. Pre- studies that purport to have measured the effects of chemicals dominately, these instances described have been in military on task performance related to roadway driving. operations wherein limited use of varying stimulant and sleep aid compounds has been permitted after a person's experience Another goal was to cull through the scientific literature to with the particular compound is established first, voluntary identify and categorize the reported research on many other consent for their use is obtained and then only under close psychoactive substances having identifiable effects on the medical supervision, with the constant scrutiny and control of cognitive, psychomotor, and physiological performance of safety officers charged to manage operational use of chemi- drivers. That is, one of the objectives was to assemble in one cals by their military teammates, partners, or "employees." source document identification (at least a listing) of what has Most of the experiments and the actual operational use of such been published already, so as to ease the task of anyone desir- chemicals documents examinations of "acute" applications, in ing additional background information on these topics. Thus, which the chemicals or drugs were taken only on a short-term in Appendix A, this synthesis presents a description of a vari- basis, usually lasting no more than several days duration. Only ety of chemical substances that drivers partake of, whether rarely did the reported studies measure drug effects in repeated the evidence for psychoactive effects was strong or not. Addi- applications over days and weeks as might be the need for tionally, this synthesis presents in the References, not only a commercial driver applications. listing of citations used in the narrative text (Appendix D web-only), but also a supplemental bibliographic reading list This literature survey therefore reaffirmed that there of secondary source documents that pertain to the topics in are only a few viable psychoactive chemical substances that this study (Appendix E web-only). commercial drivers can legitimately and safely use as sleep aids (hypnotics) or as alertness enhancers (stimulants) during In this synthesis, the coverage of the results of any indi- transportation operations. The circumstances involved in vidual study described within, by necessity, is brief. For more commercial driving in the United States are somewhat dif- specific details, motivated readers are encouraged to acquire ferent from those of U.S. military operations. Sanctioned and consult the original journal articles. The literature review pharmaceutical use in military operations requires controlled
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66 closed-loop medical and safety supervisory settings that stress an available safe sleep-inducing compound that can be used safe use of psychoactive medications for measured short without prescription. However, because it is classified as a durations intended to achieve time-limited missions. Such use "health food," the manufacture and distribution of synthetic of medications would likely be very impractical as well as melatonin is not subject to FDA approval and, therefore, con- very costly to manage in a commercial driving setting. sumers cannot be sure of the quantity, purity, and quality of the product they purchase. More research on "good quality" melatonin could be fostered with a goal of developing rec- Sleep-promoting Compounds ommended operational use protocols (recommended timing, dose levels, duration of use, etc.) for commercial drivers who Available sleep-promoting compounds and hypnotics include might benefit from using this more natural sleep promoter. classes of prescription anxiolytic agents, depressants, anti- Proper use of synthetic melatonin might be especially beneficial insomnia medications, over-the-counter (OTC) sleeping pills, after completing night driving and when daytime sleep oppor- first-generation antihistamines that induce drowsiness, syn- tunities present themselves in over-the-road operations. thetically formulated hormones such as melatonin that promote sleep, and herbal and dietary supplements touted as relaxants. Research studies on each of those categories of sleep-inducers Antihistamines as Sleep Aids are described in the literature review in this report. It is known that many commercial drivers employ OTC first-generation antihistamines (e.g., those containing diphen- Benzodiazepines hydramine) to obtain relief from seasonal allergies; however, in some applications, drivers take them simply to assist in The literature survey confirmed that the variety of benzodi- falling asleep. Several OTC sleeping pills also contain diphen- azepines used to induce sleep present a number of serious hydramine or similar compounds that induce drowsiness. limitations for operational use in the transportation industry Appropriate usage protocols (times of administration, dose context. As the research results depicted in this survey con- levels, cautions, and so on) could be developed for use of such vey, a large number of the hypnotics described in this report sleep-inducing compounds, specifically for application to the either have already been, or might in the future be, declared many work-rest schedules inherent in the commercial driving unsuitable for commercial driver use on the roadway. community. Additional research may be required to examine the combined use of melatonin and antihistamines as sleep aids. Nonbenzodiazepines Additional research could be done to confirm whether or The literature survey also points out that some of the newer not the newer second- and third-generation antihistamines prescription sleep-inducing drugs, nonbenzodiazepines with declared to be nondrowsy, are as efficacious for treatment shorter half-lives, may be preferable to older drugs for use of seasonal allergies as their advertisements claim. Then, as anti-insomnia treatments, because the amount of sleep protocols for their appropriate and safe use for treatment of inertia or hangover effects rapidly dissipate as the drugs allergies should be developed and promulgated for the com- clear the body's biological systems. Some of these newer mercial driving community. nonbenzodiazepines (e.g., Zolpidem, Zopiclone, Zaleplon, Indiplon, Eszopiclone, Ramelteon, and Alterial) might feasibly Alcohol to Induce Sleep be applied to induce short "naps" in sustained work scenarios, and therefore could be evaluated more closely by means of As the literature review confirms, the use of alcohol to put one more scientific testing for their potential application as pre- to sleep brings about risks that the sleep, and of REM dream- scribed sleep-inducing compounds in the commercial driving ing sleep as well so obtained may be disrupted in the later, community. Some of these hypnotics are already being pre- deeper stages of sleep and therefore may not be as restful as scribed by physicians to drivers, presumably at least to combat intended. With larger amounts of alcohol there is always the persistent insomnia. However, the FMCSA expert medical risk of hangover upon awakening. panel on psychiatric disorders and driver safety recommended "No" to nonbenzodiazepine hypnotics, and stated that a driver must wait seven half-lives if such drugs are used acutely, or Stimulants and Alertness Enhancing Compounds seven half-lives plus one week, if under their chronic use A large number of alertness-enhancing or wake-promoting (Expert Panel Aug. 2009, p. 7) (http://www.fmcsa.dot.gov/ compounds is available; however, it appears there is no solid rules-regulations/TOPICS/mep/report/Medical-Expert-Panel- scientific foundation for finding most of them suitable for Psychiatric-Psychiatric-MEP-Panel-Opin.pdf). use in commercial driving applications. Whereas caffeine, nicotine, and energy booster supplements are viewed as being Melatonin acceptable for driving situations, almost all other effective (efficacious) stimulant drugs are not. Some stimulant com- The popular and natural sleep hormone melatonin, produced pounds are illicit and illegal drugs (e.g., cocaine) and are synthetically and sold in health food stores, is identified as deemed too deleterious to driving performance to permit their
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67 use during operations on the road. For those licit-prescribed Even with the significant amounts of caffeine research cited Schedule II stimulants, an FMCSA expert panel has opined that in the literature review however there does not appear to be a there is inadequate evidence for or against their safe use in conveniently available "recommended caffeine use protocol" commercial driving, and recommended "continued monitoring" for how much (dose) and when to take in caffeine during of the medical literature (Hartenbaum et al. 2006). commercial driving operations. The paucity of actual highway driving studies examining effects of caffeine suggests that more research on this obvious fatigue countermeasure needs to Modafinil be focused on delineating numerous usage protocol variables for commercial driver alertness and fatigue management Described as an eugregoric compound (and therefore not programs. It would be helpful to have an information packet an amphetamine-like drug), a "wake-promoting substance," that provides basic information about protocols for the use of modafinil offers much promise for use as a stimulant, with caffeine, pointing out at least that as with any stimulant, the probable application to the commercial driving community. body adjusts to large intakes of caffeine, necessitating larger Modafinil has been shown to increase alertness, memory, and doses to obtain the same effect; that it takes about 20 min after planning activities in healthy adults. As laboratory research consuming caffeine for the stimulation effects to kick-in; and described in the review indicates, modafinil provides many of that depending on the time of consumption before attempting the same stimulant benefits that caffeine and other stronger to sleep, caffeine will affect sleep latency, quality, and rest- stimulants provide, but with slightly different physiological fulness. The differences in caffeine formulation (e.g., coffee, side effects, some of them less offensive, such as not being as soft drinks, chewing gum, mints, and energy bars and drinks) threatening to blood pressure as caffeine. A very important also could be delineated and a description of some of the and interesting observation about modafinil is that, unlike any physiological side effects of caffeine use (e.g., raises blood other stimulant (including caffeine), while a person is taking pressure and nervousness) could be provided as well. modafinil, he or she can still decide to go to sleep; that is, to take a nap without interference from the "drug." That feature of One aspect of the research on caffeine that may warrant modafinil could be explored in subsequent research programs. further exploration is the potential value of combining slow- release caffeine and a short nap (30 min) a technique reported Although several U.S. military medical laboratories con- as being successful in counteracting drivers' sleepiness in a tinue to research modafinil, more research could be specifi- partial sleep deprivation study. Not much information was cally designed to answer questions regarding the potential located regarding either slow-release caffeine or combining wider application of modafinil (or armodafinil) to commercial naps with such stimulants as fatigue countermeasures. driving scenarios. In particular, research could help develop a suitable "usage protocol," including identification of recom- mended dose levels, the time of day of administration, the time Nicotine of administration within a work shift or during adjustments to shift changes, any limitations for the duration of more long- Although nicotine is classified as a stimulant, the scientific term usage of modafinil or armodafinil (e.g., weeks/months), literature describing its effects with regard to cognitive perfor- and determination of whether or not there are interactions mance is equivocal. Whereas some laboratory evidence pre- with other chemical compounds drivers consume, especially sented indicates that nicotine can produce the enhancement caffeine and antihistamines. Financial affordability of these of certain aspects of attention and cognition, no studies report relatively expensive medications might also be an inhibitor true enhancement of sensory abilities, selective attention, to commercial driver use. learning, and other cognitive abilities such as problem solving and reasoning. Furthermore, nicotine has been demonstrated not to be effective in restoring alertness and cognitive perfor- Caffeine mance during laboratory testing of sustained performance in the face of full sleep deprivation (48 h). Accordingly, any Caffeine, the ubiquitous stimulant compound, is the most informational packets prepared for the commercial driving widely consumed psychoactive substance available. The litera- community should clearly highlight known facts to dispel ture demonstrates that caffeine offers a relatively safe and effec- common myths held about nicotine's positive utility. Too many tive means of maintaining or restoring cognitive performance drivers are under the misimpression that the nicotine in their even under conditions of operational stress (see numerous cigarettes will help maintain their alertness, and research citations in text). Caffeine restores cognitive function during illustrates that it probably does not. prolonged wakefulness, and it can enhance certain types of cognitive performance, most notably vigilance and reaction times, in rested individuals, regardless of whether or not they Supplements: Nutritional, Dietary, and Other are regular caffeine users. The doses of caffeine most likely to be effective without causing undesirable mood effects are A very large number and a wide variety of supplements are within the range of 100 to 600 mg, and this amount of caffeine available and are being consumed by a large cross section of can easily be obtained in many readily available sources, Americans, no doubt including numerous commercial drivers. including by drinking caffeinated coffee. As the literature survey herein suggests, the synthesis team