Final answer:
Brain oxygen consumption is increased during REM sleep due to high brain activity similar to that of an awake state, which is reflected in the brain's metabolic activity.
Step-by-step explanation:
In REM (Rapid Eye Movement) sleep, brain oxygen consumption is generally increased. This is due to the fact that brain activity during REM sleep is quite similar to that during wakefulness, featuring active dreaming and high brain activity. REM sleep is associated with significant brain activity because of its involvement in processes such as dreaming, learning, and memory consolidation. As a result, during REM sleep, there is an increased energy consumption in brain regions, much like when a person is awake. Moreover, sleep studies using EEG (Electroencephalography) show that the brain waves in REM sleep are similar to those during an awake state, further indicating higher metabolic activity and thus, increased oxygen consumption.