Review of electroencephalography signals approaches for mental stress assessment

Eyad T. Attar

doi:10.17712/nsj.2022.4.20220025

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- Mental stress and EEG band power relationship.

EEG Waveforms	Relation to mental stress	EEG waveforms behavior
Delta (0.5 to 4 Hz)	Delta waves are associated with healing and regeneration during our deep sleep cycles. A few minutes of allowing our brains to tune into delta waves can decrease overactivity and stress of anxious thinking^30,31	Excessive: Brain injuries, learning problems, inability to think, severe ADHD Inadequate: Inability to rejuvenate the body, inability to revitalize the brain, poor sleep Optimum: Immune system, physical treatment, restorative / intense sleep³⁴
Theta (4 to 7 Hz)	Theta is detected in anxiety and behavioral with activation and inhibition. When the theta wave occurs, it mediates and promotes interesting behaviors, for example, learning and memory. Under uncommon emotional situations, for instance, stress, there may be an imbalance of three key transmitter systems, which results in aberrant behavior^35-37	Excessive: ADHD, unhappiness, hyperactivity, impulsivity, daydreaming Inadequate: Nervousness, low emotional perception, stress Optimum: Imagination, emotional relationship, intuition, rest³⁸
Alpha (8 to 12 Hz)	Regular meditation and relaxation have been shown to enhance alpha waves and lower beta waves in the brain waves of effective thought and learning. This is the reason why it is the most recommended for lowering stress. When alpha’s reaction is non-existent or negative, the possibility of traumatic stress is suspected. In most harshly emotionally distressed fibromyalgia patients, the QEEG showed relatively minimal alpha activity and the most considerable alpha power in the group with the least emotional distress^39-41	Excessive: Dreaming, inability to concentrate, too calm Inadequate: Nervousness, high stress, insomnia, OCD Optimum: Rest⁴²
Beta (13 to 30 Hz)	Stress, “traffic jam,” overwhelmed, cannot process activated networks. Beta wave is increased during stress^44,45	Excessive: Adrenaline, high arousal, failure to relax, stress Inadequate: ADHD, daydreaming, depression, poor cognition Optimum: Conscious focus, memory, problem-solving⁴⁸
Gamma (30 to 80 Hz)	A fully standardized task with high ecological validity⁴⁹	Excessive: Nervousness, high-level arousal, stress Inadequate: ADHD, depression, knowledge disabilities Optimum: Binding senses, cognition, knowledge handling, learning, awareness, REM sleep⁵⁰