Question

In which sleep stage are 20%-50% Delta waves observed?

a) REM stage
b) NREM stage 1
c) NREM stage 3
d) NREM stage 4

Answer 1

Delta waves characterize NREM stage 3 sleep, which is identified as deep sleep or slow-wave sleep, marked by a significant physiological slowdown and high amplitude waves.

Step-by-step explanation:

In which sleep stage are 20%-50% Delta waves observed? The correct answer is c) NREM stage 3. Delta waves, which are low frequency (1-3 Hz) and high amplitude, characterize slow-wave NREM stage 3 sleep. This stage of sleep is also known as deep sleep or slow-wave sleep and is marked by significant physiological changes such as a decrease in heart rate and respiration, making it more difficult to awaken an individual from this stage.

Sleep spindles and K-complexes are most often associated with NREM stage 2 sleep, not stage 3. Furthermore, it is important to note that REM sleep, despite being associated with high brain activity similar to wakefulness, does not present with a high proportion of delta waves, hence ruling out REM sleep.