Final answer:
The level of consciousness is regulated by the Reticular Activating System (RAS), a network of neurons located in the brainstem.
Step-by-step explanation:
The level of consciousness is regulated by the Reticular Activating System (RAS).
The RAS is a network of neurons located in the brainstem, specifically the midbrain and upper part of the pons. It plays a crucial role in maintaining wakefulness, alertness, and arousal by filtering sensory information and sending it to the cerebral cortex.
For example, if you see a flashing light while you're sleeping, the RAS will filter out that irrelevant information to keep you asleep. However, if someone calls your name, the RAS will wake you up because it recognizes the significance of that stimulus.