What is the distance from Fpz to F8?

The correct distance from Fpz to F8 is considered to be approximately 7 cm. In the context of electroencephalography (EEG) and polysomnography (PSG), the 10-20 system of electrode placement provides a standardized method for placing electrodes on the scalp. According to this system, the distances between the electrode sites are specifically defined for consistency in measurements and comparisons across studies.

The distance of 7 cm between Fpz and F8 reflects the ability to maintain a proportional spread of electrodes across the head, which is crucial for capturing brain activity effectively during sleep studies. Accurate placement according to these specified distances ensures that recorded data are reliable and can be interpreted correctly by clinicians.