FHM has developed an application system, named “Flicker health management system” (FHMS), with which everybody can measure his mental fatigue in an objective way whoever, whenever and wherever he is. It is well known the flicker fusion threshold (FFT) can be used as an objective method to measure mental fatigue, since it decreases its value as he get tired mentally. It requires, however, a big, dedicated and expensive measurement device to measure FFT. The technology of FHM enables to measure FFT using general-purpose equipments such as cellular phone, smart phone, tablets, PC and car-navigation system. FHM also provides “Flicker Health Management System Lite” as a subset of FHMS for monitoring his history of measured mental fatigue very easily.