What is the expected movement of the E1 and E2 channels on polysomnography when the patient looks up?

When a patient looks up, the expected movement of the E1 and E2 channels on polysomnography shows that they will move toward each other. This is due to the physiological response of the eye muscles. When a person gazes upwards, the electrical activity of the muscles that control eye movement changes, typically resulting in a more positive deflection in both E1 and E2 electrodes, which are positioned on either side of the eyes. Because of this upward gaze, the electrical potentials of these electrodes begin to converge, leading to their signals appearing closer to one another on the polysomnography readout.

This behavior is significant because it helps in identifying eye movements and contributes to understanding the sleep stages and wakefulness of the patient, making it crucial for accurate interpretation during a sleep study.