What is indicated by a downward deflection on an EOG reading?

A downward deflection on an electrooculogram (EOG) reading typically indicates that the patient is looking away from the electrode. The EOG measures the potential differences caused by the movement of the eyes, and when the eyes rotate, the potential changes accordingly. If the patient looks in the direction that causes the electric dipole formed by the cornea and retina to point away from the electrode, this results in a downward deflection on the EOG tracing.

This means that significant eye movement is taking place, which is essential for interpreting sleep stages and identifying periods of rapid eye movement (REM). In REM sleep, for instance, one expects to see more fluctuating EOG signals due to the characteristic eye movements associated with this sleep phase. Therefore, understanding these cues allows polysomnographic technologists to assess the patient's sleep architecture more accurately.

Examining the other options, a positive charge being detected would not specifically relate to a downward movement, and stating no eye movement is occurring contradicts the nature of the downward deflection indicating a specific eye movement direction. Lastly, while REM sleep is associated with significant eye movements, the question specifically focuses on the meaning of the downward deflection rather than confirming the sleep stage. Thus, the information about