In a medical or biological context stress is a physical, mental, or emotional factor that causes bodily or mental tension. In general, stress is related to both external and internal factors. External factors include the physical environment, including your job, your relationships with others, your home, and all the situations, challenges, difficulties, and expectations you're confronted with on a daily basis. Internal factors determine your body's ability to respond to, and deal with, the external stress-inducing factors including your nutritional status, overall health and levels, emotional well-being, and the amount of sleep and rest you get.
Stress is a normal part of life that can either help us learn and grow or can cause us significant problems. Stress releases powerful neurochemicals and hormones that prepare us for action (to fight or flee). If we don't take action, the stress response can create or worsen health problems (www.medicinenet.com).
Excess stress can manifest itself in a variety of emotional, behavioral, and even physical symptoms:
- Changes in sleeping habits.
- Muscle tension.
- Gastrointestinal problems.
- Changes in eating habits.
- Loss of enthusiasm or energy.
- Mood changes, like irritability and depression.
In Biosignals, Stress can be studied through physiological signals like blood volume pressure, galvanic skin response, pupil dilation, skin temperature, electrocardiogram, breath, electromyogram, electroencephalogram.
Most common approaches in stress detection are Galvanic Skin Response (GSR) and Heart Rate (HR).
A stress-detection system inherits several characteristics from biometric systems. First of all, a template extraction is required so that the system could create a profile in order to contrast, in future accesses, whether a user is actually under stress. This template is based on specific characteristics extracted from individual concerning parameters from the physiological signals HR and GSR.
On the other hand, once the user is associated to a template, the individual is able to access the system, and therefore, a template comparison is required.
The main characteristics of this system is its noninvasiveness, fast-oriented implementation, and outstanding accuracy in detecting stress when compared with other approaches. In other words, the system can detect stress almost instantly, allowing possible integration in real-time systems.
- Aliveness detection (e.g., detecting if an individual is accessing a biometric system with an amputated finger).
- Civil applications (e.g., driver control).
- Withdrawing money from a cash dispenser.
- Electronic voting (e.g., someone is forced to emit a certain vote).
In other words, a wide variety of scenarios can benefit from this approach due to its noninvasiveness, the likelihood to be embedded on current security systems, and its possibility in detecting stress in real time.