What electrical changes are observed in the brain during REM sleep?

During REM (Rapid Eye Movement) sleep, the brain demonstrates increased activity, which can be observed through an EEG. This phase of sleep is characterized by brain wave patterns that resemble those seen during wakefulness—marked by a mix of theta and beta waves. The heightened brain activity during REM sleep supports vivid dreaming and various cognitive processes that occur during this stage.

In addition to increased brain activity, there is typically low muscle tone during REM sleep, a phenomenon known as REM atonia. This is crucial as it prevents individuals from physically acting out their dreams, thus protecting them from potential injuries. This combination of heightened brain activity and decreased muscle activity is unique to REM sleep and distinguishes it from other sleep stages, such as NREM sleep, where brain activity is generally lower, and different wave patterns are observed.

In contrast, the other options do not accurately describe the brain activity during REM sleep, as the hallmark of this stage is indeed the surge in brain activity paired with the relaxation of muscle tone.