On setting up the alarm, make sure you select the time interval for the alarm to go off. If there is no REM phase during the set up of the time interval, the alarm will go off at the end of the selected interval.
For the correct functioning of the alarm feature it is important to set up the time interval of at least 30 minutes, preferably more.
You can read more on sleep monitoring and the smart alarm feature at https://healbe.com/info_sleep/
If these recommendations don't help, please email us at gobe@healbe.com with a screenshot of your alarm settings in your HEALBE app and let us know the exact date and time when you experienced the problem.