SAFTE-FAST launched a new webinar series called FAST Talk this summer. This bi-monthly (by which I mean every other month, not twice a month) series will feature a scientist who conducts research relevant to fatigue risk management. The webinar series is open to the public; viewers can attend the talks live by registering through Zoom or watch recordings of earlier talks through our events series page.
Our most recent talk featured Dr. Tracy Jill Doty, Chief of the Sleep Research Center at the Walter Reed Army Institute of Research. Dr. Doty talked about “Cutting Edge Solutions for Fatigue Mitigation”. You can watch the video here. Dr. Doty talked about 2B-Alert-- an application being developed for the military to plan caffeine optimization under conditions of sleep deprivation. You can access a demo of the 2B-alert app here. She also highlighted the development of a transcranial direct current stimulation (tDCS) wearable device that applies a low electric current to the wearer’s scalp to mimic deep sleep. Such a device may eventually reduce the sleep time necessary to recover from fatigue. Learn more here.
Pivotal to any cutting-edge strategy for fatigue mitigation is demonstrating that the solution actually works. The psychomotor vigilance task (PVT) is every fatigue scientist’s quick answer to the question, “what is a reliable objective measure of fatigue?” During her FAST talk, Dr. Doty admitted that while she was a fan of the test and could talk about the PVT all day, there is also space for novel biomarkers of fatigue to replace the need for reaction time testing. The PVT is good as a quick test for alertness because it is so simple—you literally just have to hit a button as soon as you see a stimulus. This means that there is no learning curve and no practice effects. In other words, the test is as valid for a rookie as it is for a veteran. The test is also so simple that you cannot game the system—fatigue will reveal itself.
However, we can’t forget that fatigue is tricky. Reaction times on the PVT vary a fair amount even between well-rested individuals. The SAFTE-FAST output metric Effectiveness is expressed as a percentage scaled to a fully rested person's normal best performance on the PVT because you cannot expect any one specific speed on the PVT to indicate a well-rested person versus a tired person. Person A may be faster than Person B at any level of sleep deprivation. Effectiveness is an indication of whether a person is performing at their own personal best or not; it is not a comparison between people. SAFTE-FAST predictions have been able to circumvent the inter-individual differences issue, but novel strategies aiming to curb fatigue risk still have to deal with the fickleness of measuring fatigue via the PVT or any replacement metric.
Fatigue manifests as an increase in the variability of responses rather than a steady, consistent cognitive decline. Instead of completing a task perfectly 10 times out of 10, for example, a fatigued person may complete the task perfectly 9 times out of 10 and fail once. So, when a researcher is analyzing test results to determine the level of fatigue, they must always wonder if the results look good because the test-taker was well-rested or if the taker was tired but got lucky. Conversely, if the results look bad, there’s always a chance that something other than fatigue caused the poor performance. It is easier to control for intervening factors in a laboratory study, but it is much more difficult to control for those variables when fatigue tests move into the field. To quote Dr. Doty’s FAST talk, “understanding how many PVTs you need and when you need them is an important point”. The variability that fatigue introduces into the system is what makes it such a large safety concern as well as a difficult topic to study. Whether you are trying to establish that fatigue is present or that it is absent, you can’t just check once and be done. A cruel joke is also that extended repetition of the PVT results in fatigue due to time on task. This means that longer test sessions are not the answer either.
Dr. Doty also highlighted the importance of looking at recovery from fatigue. How long does it take someone to get back to their own baseline? This issue was also addressed in Dr. Van Dongen’s FAST Talk from June focusing on the allostatic process. You can watch the video here. The allostatic process is a biological phenomenon like the circadian rhythm or the homeostatic urge to sleep. The allostatic role in the context of sleep is that if you have been sleeping poorly over a long period of time, a few nights of really good sleep are not going to erase the damage done to your performance capabilities. Exposure to prior poor sleep impacts your ability to recover from acute poor sleep. Currently, there is no biohack or replacement for consistently good sleep. However, tools like transcranial stimulation or caffeine optimization can improve short-term performance in operational situations. Please listen to Dr. Doty’s talk to learn more.
Dr. Fran Pilkington-Cheney will talk about management and mitigation of sleepiness during shift work for the next FAST talk on November 15th at 9AM EST/ 2PM CET after the SAFTE-FAST User Conference. This year’s user conference will be held in Amsterdam with our host partner KLM on October 29-30, 2024. Registration is now open for SAFTE-FAST customers to sign-up for two days of presentations, panels, workshops and social activities in Amsterdam. Go to our conference site or contact your account manager for more information. We hope to see you in real life in October and on Zoom at FAST talks in the future!
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