What is the best immediate action when intermittent 60 Hz activity occurs in the F4-M1 electrodes during REM sleep?

During REM sleep, the presence of intermittent 60 Hz activity in the F4-M1 electrodes suggests possible electrical interference, commonly from alternating current (AC) sources. Relying on F3-M2 provides an alternative reference point since it captures data from a different electrode location that may be less affected by this interference. This can help ensure that the ongoing recording reflects the patient's true brain activity without the contamination from the 60 Hz interference.

Exploring the other options, increasing the gain on the EEG amplifier would amplify all signals, including the unwanted 60 Hz artifacts, which could lead to misinterpretation of the patient's neurological status. Checking the electrode impedance is certainly a good practice, but it might not resolve the immediate issue of interference affecting the F4-M1 electrodes. Switching to a different montage could potentially overlook pertinent information or signal integrity from the current setup without addressing the specific environmental noise affecting the F4 electrode. Thus, relying on F3-M2 can serve as the most effective immediate response to mitigate the impact of the interference while continuing to monitor the patient.