In a method and apparatus for monitoring a parameter, such as a concentration level, of an easily ignited gas, such as hydrogen, includes a wake-up device that is connected to a current/voltage supply, and can switch the monitoring unit from a state of rest into an active state after an adjustable time interval. The device according to the invention can be used in a fuel cell system or in a vehicle. Furthermore, the invention relates to a method for monitoring the concentration of an easily ignited gas.