Fatigue describes a state of tiredness or exhaustion. In general usage, fatigue often follows prolonged physical or mental activity. When fatigue occurs independently of physical or mental exertion, or does not resolve after rest or sleep, it may have other causes, such as a medical condition.
Sleep debt or sleep deficit is the cumulative effect of not getting enough sleep. A large sleep debt may lead to mental or physical fatigue, and can adversely affect one's mood, energy, and ability to think clearly.
Sleep inertia is a physiological state of impaired cognitive and sensory-motor performance that is present immediately after awakening. It persists during the transition of sleep to wakefulness, where an individual will experience feelings of drowsiness, disorientation and a decline in motor dexterity. Impairment from sleep inertia may take several hours to dissipate. In the majority of cases, morning sleep inertia is experienced for 15 to 30 minutes after waking.
Neuroergonomics is the application of neuroscience to ergonomics. Traditional ergonomic studies rely predominantly on psychological explanations to address human factors issues such as: work performance, operational safety, and workplace-related risks. Neuroergonomics, in contrast, addresses the biological substrates of ergonomic concerns, with an emphasis on the role of the human nervous system.
Mental chronometry is the scientific study of processing speed or reaction time on cognitive tasks to infer the content, duration, and temporal sequencing of mental operations. Reaction time is measured by the elapsed time between stimulus onset and an individual's response on elementary cognitive tasks (ECTs), which are relatively simple perceptual-motor tasks typically administered in a laboratory setting. Mental chronometry is one of the core methodological paradigms of human experimental, cognitive, and differential psychology, but is also commonly analyzed in psychophysiology, cognitive neuroscience, and behavioral neuroscience to help elucidate the biological mechanisms underlying perception, attention, and decision-making in humans and other species.
Space medicine is an area in aerospace medicine that focuses on the medical care of astronauts and spaceflight participants. The spaceflight environment poses many unique stressors to the human body, including G forces, microgravity, unusual atmospheres such as low pressure or high carbon dioxide, and space radiation. Space medicine applies space physiology, preventive medicine, primary care, emergency medicine, acute care medicine, austere medicine, public health, and toxicology to prevent and treat medical problems in space. This expertise is additionally used to inform vehicle systems design to minimize the risk to human health and performance while meeting mission objectives.
A continuous performance task, continuous performance test, or CPT, is any of several kinds of neuropsychological test that measures a person's sustained and selective attention. Sustained attention is the ability to maintain a consistent focus on some continuous activity or stimuli, and is associated with impulsivity. Selective attention is the ability to focus on relevant stimuli and ignore competing stimuli. This skill is associated with distractibility.
The psychological and physiological effects of meditation have been studied. In recent years, studies of meditation have increasingly involved the use of modern instruments, such as fMRI and EEG, which are able to observe brain physiology and neural activity in living subjects, either during the act of meditation itself or before and after meditation. Correlations can thus be established between meditative practices and brain structure or function.
David F. Dinges is an American sleep researcher and teacher.
Sleep deprivation, also known as sleep insufficiency or sleeplessness, is the condition of not having adequate duration and/or quality of sleep to support decent alertness, performance, and health. It can be either chronic or acute and may vary widely in severity. All known animals sleep or exhibit some form of sleep behavior, and the importance of sleep is self-evident for humans, as nearly a third of a person's life is spent sleeping.
The CDR system is a computerized battery of cognitive tests designed in the late 1970s by Professor Keith Wesnes at the University of Reading in Berkshire, England, for repeated testing in clinical trials. Task stimuli are presented in a laptop computer and participants respond via 'YES' and 'NO' buttons on a two-button response box, which records both the accuracy and reaction time.
It has been estimated that over 20% of adults suffer from some form of sleep deprivation. Insomnia and sleep deprivation are common symptoms of depression, and can be an indication of other mental disorders. The consequences of not getting enough sleep could have dire results, not only to the health, cognition, energy level and the mood of the person, but also to those around them. Sleep deprivation increases the risk of human-error related accidents, especially with vigilance-based tasks involving technology.
The relationship between sleep and memory has been studied since at least the early 19th century. Memory, the cognitive process of storing and retrieving past experiences, learning and recognition, is a product of brain plasticity, the structural changes within synapses that create associations between stimuli. Stimuli are encoded within milliseconds; however, the long-term maintenance of memories can take additional minutes, days, or even years to fully consolidate and become a stable memory that is accessible. Therefore, the formation of a specific memory occurs rapidly, but the evolution of a memory is often an ongoing process.
In modern psychology, vigilance, also termed sustained concentration, is defined as the ability to maintain concentrated attention over prolonged periods of time. During this time, the person attempts to detect the appearance of a particular target stimulus. The individual watches for a signal stimulus that may occur at an unknown time.
Second wind, a colloquial name for the scientific term wake maintenance zone, is a sleep phenomenon in which a person, after a prolonged period of staying awake, temporarily ceases to feel drowsy, often making it difficult to fall asleep when exhausted. They are the result of circadian rhythms cycling into a phase of wakefulness. For example, many people experience the effects of a second wind in the early morning even after an entire night without sleep because it is the time when they would normally wake up.
The Cognitive Research Corporation Driving Simulator (CRCDS) is a PC-based driving simulator used to test the effects of various factors on driving performance. The CRCDS software is ported from the National Advanced Driving Simulator (NADS).
Studies, which include laboratory investigations and field evaluations of population groups that are analogous to astronauts, provide compelling evidence that working long shifts for extended periods of time contributes to sleep deprivation and can cause performance decrements, health problems, and other detrimental consequences, including accidents, that can affect both the worker and others.
Sleeping in space is part of space medicine and mission planning, with impacts on the health, capabilities and morale of astronauts.
The International Civil Aviation Organization (ICAO) defines fatigue as "A physiological state of reduced mental or physical performance capability resulting from sleep loss or extended wakefulness, circadian phase, or workload." The phenomenon places great risk on the crew and passengers of an airplane because it significantly increases the chance of pilot error. Fatigue is particularly prevalent among pilots because of "unpredictable work hours, long duty periods, circadian disruption, and insufficient sleep". These factors can occur together to produce a combination of sleep deprivation, circadian rhythm effects, and 'time-on task' fatigue. Regulators attempt to mitigate fatigue by limiting the number of hours pilots are allowed to fly over varying periods of time.
