A wristband intended for alarming a user wearing the wristband of an irregular heart rhythm of the user is provided. The wristband comprises a sensor unit arranged to measure a signal pertaining to the heart rhythm of the user and a clock unit arranged to provide a time frame, a signal unit arranged to derive a time-resolved signal and a data storage unit arranged to store data. The wristband further comprises a power unit and an alarm unit. The wristband further comprises a frequency for calculating the frequency of the time-resolved signal, an amplitude unit for calculating the amplitude of said time-resolved signal and an analyzing unit arranged to perform a frequency analysis and an amplitude analysis and to perform the frequency analysis and the amplitude analysis simultaneously or in parallel and to send an alarm command to the alarm unit for alarming the user of an irregular heart rhythm.
