Van Dongen H.P.A.,Washington State University |
Caldwell J.A.,Fatigue Science |
Caldwell J.L.,Air Force Research Lab
Progress in Brain Research | Year: 2011
Individual differences in cognitive functioning during extended work hours and shift work are of considerable magnitude, and observed both in the laboratory and in the workplace. These individual differences have a biological basis in trait-like, differential vulnerability to fatigue from sleep loss and circadian misalignment. Trait-like vulnerability is predicted in part by gene polymorphisms and other biological or psychological characteristics, but for the larger part it remains unexplained. A complicating factor is that whether individuals are vulnerable or resilient to sleep deprivation depends on the fatigue measure considered-subjective versus objective assessment, or one cognitive task versus another. Such dissociation has been observed in laboratory data published previously, and in data from a simulated operational setting first presented here. Discordance between subjective and objective measures of fatigue has been documented in various contexts, and may be one of the reasons why vulnerable individuals do not systematically opt out of professions involving high cognitive demands and exposure to fatigue. Discordance in vulnerability to fatigue among different measures of cognitive performance may be related to the "task impurity problem," which implies that interrelated cognitive processes involved in task performance must be distinguished before overall performance outcomes can be fully understood. Experimental studies and cognitive and computational modeling approaches are currently being employed to address the task impurity problem and gain new insights into individual vulnerability to fatigue across a wide range of cognitive tasks. This ongoing research is driving progress in the management of risks to safety and productivity associated with vulnerability to cognitive impairment from fatigue in the workplace. © 2011 Elsevier B.V.
Das A.,Fatigue Science |
Das A.,Bhabha Atomic Research Center
Philosophical Magazine | Year: 2015
The phenomenological theory of martensitic transformation is well understood that the displacive phase transformations are mainly influenced by the externally applied stress. Martensitic transformation occurs with 24 possible Kurdjomov-Sachs (K-S) variants, where each variant shows a distinct lattice orientation. The elegant transformation texture model of Kundu and Bhadeshia for crystallographic variant selection of martensite in metastable austenite at various stress/strain levels has been assessed in this present research. The corresponding interaction energies have also been evaluated. Encouraging correlation between model prediction and experimental data generation for martensite pole figures at many deformed austenite grains has been observed at different stress/strain levels. It has been investigated that the mechanical driving force alone is able to explain the observed martensite microtextures at all stress/strain levels under uniaxial tensile deformation of metastable austenite under low temperature at a slow strain rate. The present investigation also proves that the Patel and Cohens classical theory can be utilized to predict the crystallographic variant selection, if it is correctly used along with the phenomenological theory of martensite crystallography. © 2015 The Author(s).
Murata Manufacturing Co. and Fatigue Science | Date: 2015-12-22
A biological state estimating apparatus includes a pair of electrocardiographic electrodes, a photoplethysmographic sensor, and a controller that includes a peak detecting section, a pulse transmission time measuring section, a correlation information storing section, and a biological state estimating section. The electrocardiographic electrodes detect an electrocardiogram signal and the photoplethysmographic sensor, which has light-emitting and light-receiving elements, detects a photoplethysmogram signal. The controller detects peaks of the electrocardiogram and photoplethysmogram signals and determines a pulse transmission time from the time difference between the respective peaks of the photoplethysmogram and the electrocardiogram signal. Memory stores information determined in advance based on the relationship between pulse transmission time and biological state. The controller further estimates the biological state of the user on the basis of the pulse transmission time, and the correlation information stored in the correlation information storing section.
Murata Manufacturing Co. and Fatigue Science | Date: 2016-05-04
A biological state estimating apparatus (1) includes a pair of electrocardiographic electrodes (11 and 12), a photoplethysmographic sensor (20), a peak detecting section (316 or 326), a pulse transmission time measuring section (330), a correlation information storing section (341), and a biological state estimating section (360). The electrocardiographic electrodes (11 and 12) detect an electrocardiogram signal. The photoplethysmographic sensor (20), which has a light-emitting element (21) and a light-receiving element (22), detects a photoplethysmogram signal. The peak detecting section (316 or 326) detects a peak of the electrocardiogram signal and a peak of the photoplethysmogram signal. The pulse transmission time measuring section (330) determines a pulse transmission time from the time difference between the peak of the photoplethysmogram signal and the peak of the electrocardiogram signal. The correlation information storing section (341) stores correlation information that is determined in advance on the basis of the relationship between pulse transmission time and biological state. The biological state estimating section (360) estimates the biological state of the user on the basis of the pulse transmission time, and the correlation information stored in the correlation information storing section (341).
Hitachi Ltd. and Fatigue Science | Date: 2014-05-28
The system enables a subject himself to decide on a proper remedial measure, without obtaining particular instruction directly from a medical professional, by providing an advice corresponding to a decision criteria of a plurality of classifications (3x4=12) stored in the storage unit, based on a plurality of autonomic nerve function age ranks and a plurality of autonomic nerve function age ranks A screening system for fatigue and stress has a storage unit which, during screening for fatigue and stress, stores master data composed of reference values for each age, a decision unit which decides by comparing a measurement data obtained by electrocardiogram and pulse wave measurement of the subject with the reference value, and outputs a result of decision classified into the plurality of classifications, and a computing unit which receives the decision results, and calculates autonomic nerve function age ranks, wherein the decision means has an autonomic nerve decision unit which decides autonomic nerve strength, and an autonomic nerve balance decision means which decides the autonomic nerve balance.
News Article | July 2, 2015
As wearable activity trackers get increasingly smart and complex, Fatigue Science is measuring one thing and one thing only — how we sleep. Fatigue Science’s Readiband looks very similar to a Fitbit or Nike Fuelband. It has a 3D accelerometer that tracks movement, impact, velocity, speed and frequency, a battery that lasts 60 days between charges, and it’s both water and pressure resistant. The band alone is not a revolutionary development, considering that even the most basic wearable fitness trackers can monitor when you’re asleep. Fatigue Science has the ability to detect sleep quality at 93 percent of the accuracy of a hospital sleep lab, but the real feat is their ability to predict human effectiveness and reaction time. The startup takes the sleep data captured by the band and runs it through a biomathematical model developed by the U.S. Military. This level of accuracy may not be essential for most of us, but for elite athletes who are required to be in top physical condition, understanding quality of sleep and how it affects performance can be a game changer (literally). The Seattle Seahawks, the Seattle Mariners, the New York Giants and the Dallas Mavericks are among a growing group of pro sports teams that have their players wearing the Readiband at night. With Fatigue Science’s Team Platform, a dashboard that aggregates data collected from all players wearing the band, coaches can make informed decisions about training and scheduling to make sure athletes are fully rested at game time. “If the Seahawks, for example, have to cross multiple time zones to go play in New York on Sunday night, they need to be able to plan in advance the right amount of sleep for their players so at game time they’re playing their best,” says Fatigue Science CEO Sean Kerklaan. “If management can determine that the travel schedule affects their players’ ability to be ready for practice the next morning, maybe they should cancel that practice,” he says. By aggregating individual sleep data across an entire sports team, doctors and coaches can analyze how long it takes for players, on average, to fall asleep after a game, how much the team is sleeping when they have days off compared to when they’re playing and traveling, and how all of this effects game-time performance. Kerklaan tells me that the U.S. Men’s National Soccer team used the band to measure which players were mature about their sleeping habits before going to the World Cup in Brazil this year. And professional sports is only one application of this technology. Fatigue Science has partnered with construction equipment manufacturer Caterpillar to prevent employees from operating heavy machinery when they’re sleep deprived. For the time being, the company is solely focused on tracking sleep and fatigue, but it plans to open its API in the near future so that users can plug in data from other sensors. “We get a lot of questions about pulse, heart rate, sweat and other sensors,” says Kerklaan. “Our position is that none of that is scientifically valid for helping you understand how fatigued you are, but our API will enhance that research and correlation.” Fatigue Science closed $3 million in seed funding last Fall from a handful of strategic angels, and Kerklaan says they’re taking their time raising a Series A because the business is cash-flow positive.
News Article | May 27, 2013
Sleep: we spend a third of our lives doing it—or at least we should. In our stressful 24/7 world with deadlines and overtime, sleep deprivation is a common problem for many people. Whether you are a student or a professional athlete, society demands us to function at our best and Fatigue Science knows that in order to give our top performance we must be well rested and fully charged. In 2007, Vancouver-based Fatigue Science was founded with the goal of creating a more effective world by applying science and technology to assist sleep, optimize performance, reduce risk and improve lives. Fatigue Science understands that scheduling for sleep is not always as simple as closing your eyes. “Studies show that in the United States, 30% of adults sleep less than 6 hours per night,” FatigueScience.com states, “and 65% of adults have sleep problems at least a few nights a week.” The new ReadiBand technology is hoping that informative personal data will reduce the risk and improve the quality of sleep. The wrist worn device was first developed in part by the US Military, where functioning through fatigue is a fact of life. Now government professionals use ReadiBand, as well as corporations around the world and even professional sports teams such as the Vancouver Canucks. The ReadiBand measures day-to-day sleep quality, quantity and timing. The sleek black wristwatch measures and analyzes the wrist movements to distinguish sleep/wake patterns. Data shows that this virtual sleep assessment has 93% accuracy, the same as a sleep lab polysomnography. Statistics gathered from the ReadiBand can then be processed through a patented and validated computer model to evaluate fatigue risk levels. Busy work schedules are important, but the body clock is not something we can ignore. Fatigue does not only affect workplace performance. Lack of sleep is dangerous in all areas of life. In the last five years, according to the Canadian Council of Motor Transport Administrators, 21 per cent of motor vehicle collisions have been the cause of fatigue. The result is about 400 deaths and 2,100 serious injuries every year. To avoid these critical accidents, Fatigue Science also developed a tool to help employers and employees chart their schedules. FAST, or the Fatigue Avoidance Scheduling Tool, is a software application which calculates fatigue risk, reaction time and other variables to help people properly schedule their work and sleep during a course of a week. Most adults require seven to nine hours of sleep to have a fully effective day. To most of us that sounds like a luxury, but sleep should be a requirement—a responsibility. Too often, we sacrifice rest to fit more activities into our day and adjust our sleep pattern on the fly. Fatigue Science shows that many people are poor at judging and managing their alertness level. Too little or too much sleep can attribute to a less than healthy lifestyle. With the help of Dr. Steve Hursh, who has 23 years of experience at the Pentagon, Fatigue Science created a model by comparing fatigue to blood alcohol content. Gym memberships, organic diets and now Fatigue Science; there will always be new advancement to healthy living. But as long as we find the balance between work and rest, we can mitigate weariness and continue fulfilling our responsibilities and doing the activities we love to our full capacity.
News Article | January 16, 2015
If you're a diehard Vancouver Canucks fan, you've already heard of Fatigue Science. Years ago it was discussed whether Fatigue Science's sleep bracelet was one of the Canucks' secret weapons. Well, it was—and it turns out the Canucks aren't the only professional sports team to be quietly utilizing the Canadian startup's potent technology. Fatigue Science claims to have the only technology in the world that can calculate how "hours of sleep" equate to "performance, reaction times and effectiveness," which is why their growing client includes the US Olympic Committee, Canadian Olympic Program, and the Australian National and Olympic Teams. RELATED: How One Startup is Making Sleep the Next Big Thing in Pro Sports This season the Super Bowl Champion Seattle Seahawks are among the top teams of the National Football League with an impressive 12-4 record, or a win rate of 75%. They're currently on the league's longest win streak of the season, having won six games in a row. While Fatigue Science obviously isn't solely responsible for their success, we know the team has been actively using Fatigue Science's technology since 2013 to rest better, and, as a result, perform better on the field. SEE ALSO: Fatigue Science Develops New Technology to Help Sleep Studies are mounting that show sleep is perhaps more important than anybody once believed, pointing to signficiant variances in performance—not just at sports, but at work and in general life—based on the quality and consistency of one's sleeping habits. "We have few teams in the NFL using the Readiband system now, and we're careful not to take credit for their wins. Those that are using our technology generally recognize that there is value in managing sleep with objective data, among other key pieces related to performance like training, heart rate, nutrition," Fatigue Science CEO Sean Kerklaan recently told Techvibes. "These teams, including the Seattle Seahawks, are learning how to apply technology and analytics in building complete athlete management programs to ensure players are healthy and consistently ready to perform at a high level. We're excited to be a part of this movement in professional sports and looking forward to watching another great Super Bowl."
News Article | September 17, 2013
If you're a Vancouver Canucks fan you've likely heard of Fatigue Science. Five years ago Vancouver Sun writer Iain MacIntyre wondered if Fatigue Science's sleep bracelet was the Canucks "secret weapon". Hockey Night in Canada's Elliotte Friedman followed up with a feature which included interviews on the technology with enforcer Darcy Hordichuk and GM Mike Gillis. With Fatigue Science's help, the Canucks were able to improve their road record dramatically and Gillis was able to convince the NHL to ease up on the Canucks historically unfair road schedule and travel requirements. But more important, the Canucks were able to secure exclusive rights to the sleep tracking technology for four years and have kept it off of other NHL teams' wrists. In the past five years wearable technology and the concept of "quantified self" has taken off. It's clear that consumers want wearable devices to track activities and gather their own data. And Silicon Valley is hot on this trend. Jawbone just raised $100 million but is still struggling to meet their client demands and Fitbit has raised over $43 million from hungry investors. But is simply tracking your number of daily steps or hours of sleep enough to make any sort of significant change to you lifestyle and well-being? Apps and smart watches that simply report ''hours of sleep'' are not enough to help consumers achieve their best, whether if be maximizing performance or cutting down reaction times. Fatigue Science has the only technology in the world that can calculate how "hours of sleep" equate to "performance, reaction times and effectiveness." And it looks like they are on two something with a growing client list that includes the Canadian Soccer Association, US Olympic Committee, Canadian Olympic Program, and the Australian National and Olympic Teams. According to Fatigue Science CEO Sean Kerklaan, professional teams in the MLS and Premier League as well as the NBA and NFL are also testing the technology with announcements pending. Considering the game-changing affects that the Vancouver Canucks were able to experience in the first year of use, first-mover advantage in other leagues could be worth millions. Kerklaan shared with Techvibes that Fatigue Science is "actively raising capital to scale their business to meet the demand for our technology and pursuing licensing partnerships to broaden the consumer reach of our algorithm so millions of people can benefit."