What happens when a patient looks toward an EOG electrode during a sleep study?

When a patient looks toward an Electrooculogram (EOG) electrode during a sleep study, it causes a positive charge or downward deflection in the EOG tracing. This occurs because the EOG measures the electrical potential difference between the eyes, which is influenced by eye movement.

When the eyes move, especially in the horizontal direction, the electrical potential shifts due to the orientation of the retina and the associated dipole. Looking toward the electrode increases the positive charge at that electrode relative to the distance electrode, resulting in a downward deflection on the monitoring system. This characteristic response allows technologists to evaluate eye movements effectively, which can be important in the analysis of sleep stages and sleep disorders.

While other options may describe different scenarios, they do not accurately reflect the physiological changes that occur in the EOG signal when a patient looks toward an electrode.