In the context of sleep studies, what does "EMG" stand for?

In the context of sleep studies, "EMG" stands for Electromyography. This technique measures the electrical activity of muscles, which is crucial during polysomnography to assess muscle tone, particularly in the chin and legs, during different sleep stages. Monitoring EMG helps identify various sleep disorders, such as periodic limb movement disorder or REM sleep behavior disorder, by detecting muscle activity associated with these conditions.

Electroencephalography (EEG) focuses on brain wave activity, and while it's essential for understanding sleep stages, it does not assess muscle activity. Electrocardiography (ECG) measures the electrical activity of the heart and is not relevant to muscle activity monitoring in sleep studies. Electrosomnography is not a standard term used in these contexts. Thus, understanding EMG's role in measuring muscle activity provides critical insights into the assessment of sleep disorders, making it the correct answer.