Final answer:
To determine if someone is dreaming while asleep, researchers can use an EEG to monitor the brainwave activity during REM sleep, which is the stage where dreaming occurs.
Step-by-step explanation:
To determine if someone is dreaming while asleep, researchers can use an EEG to monitor the brainwave activity. During REM (rapid eye movement) sleep, the brainwave patterns on the EEG resemble those observed when a person is awake. This is the stage of sleep where dreaming occurs. The brainwaves during REM sleep are characterized by a combination of high brain activity and the absence of muscle tone. This information helps researchers study sleep patterns and understand the different stages of sleep.