If your Redmi Watch 5 Active is not receiving message notifications at night, it is due to the DND function or Sleep mode being activated. Check the Mi Fitness APP to see if you've enabled these settings and set specific work and rest periods. During these periods, your watch will enter DND mode, and you will not receive notifications for incoming calls or APPs. However, system alerts, such as alarms, will still function and provide reminders. Adjusting or disabling these settings can restore full notifications during nighttime.