DIAGNOSIS You have a schedule or 'Auto' mode enabled in the veSync app. The most common culprit is an unintended schedule set for overnight hours, or the unit switching to Auto mode based on its sensor reading.
FIX Open the veSync app, select your Vital 100S, and go to the Schedule tab. Delete any scheduled on/off times you don't want. Then, on the main device screen, tap the mode icon and switch it from 'Auto' to a manual speed (like Sleep or Low). The display lights will turn off in Sleep mode.
IF THAT DIDN'T WORK Check for a 'Child Lock' setting in the app or on the physical buttons. If Child Lock is on, the physical buttons are disabled, but the app and schedules still work—someone might be accidentally tapping the app icon.
HEADS UP In 'Auto' mode, a sudden spike in particles (like fluffing a blanket) can cause it to ramp up. For uninterrupted sleep, use 'Sleep' mode which locks the speed to the quietest setting and turns off all lights.