Question about Beurer Wl 75

It is possible to use only the light wake-up function without any sounds.
The USB port is only for charging. It should work via Bluetooth, but I've never tried it. The quality of the built-in speaker isn't great either. But I don't think that's a bad thing, it's fine for the alarm tones.
I have the phone in flight mode, with a sleep phase alarm clock (Sleep as a Droid), the programmed alarm time as with the Beurer, with both 20 minutes "lead time". This usually works perfectly, as the alarm clock is very bright I usually wake up before the smartphone alarm.
Really recommendable!