What is the name and frequency of the majority of the electromagnetic waves produced during non–rapid eye movement (NREM) sleep stage 4 (name, frequency, respectively)?
A. Delta, <4 Hz
B. Theta, 4–7 Hz
C. Alpha, 8–12 Hz
D. Beta, 13–24 Hz
Correct Answer: A
Foundational Concept: 6 Biological, psychological, and sociocultural factors influence the ways that individuals perceive, think about, and react to the world
Content Category: 6B Making sense of the environment
Scientific Reasoning and Inquiry Skill: 1 Knowledge of Scientific Concepts and Principles
A is correct. During stage 4, 50% or more of the waves are delta waves, which have a frequency of 4 Hz or less. During this stage, sleep is deepest and the waves are slowest and largest in amplitude. Human growth hormone is released, boosting restorative biological processes; metabolic functions slow down; breathing becomes slow and regular; muscular activity is limited; and no dreams are thought to occur. It is very difficult to wake a person up during this stage, and the sleeper will wake up confused. Somnambulism and sleep terrors can occur.
B. This is incorrect. Theta waves are produced during sleep stages 1, 2, and 3; very deep relaxation; and meditative states. During stage 3, there are 50% or more theta waves, which have a frequency between 4 and 8 Hz. In stage 2, the electromagnetic phenomena of spindles and K-complexes occur.
C. This is incorrect. Alpha waves are emitted during awake states of overall deep relaxation, such as during meditation, hypnosis, and listening to music, and during REM and non-REM sleep stage 1. The person is conscious, feels drowsy, or experiences light sleep.
D. This is incorrect. Beta waves characterize the normal waking, conscious, thinking, focused, and alert psychophysiological state of consciousness. They are also produced under stressful situations and during REM.
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