My sound keeps shutting off overnight

[Debbie Hanna]

I am trying to listen to music over night from my phone on headphones. But every 15 minutes or so it is shutting off. I turn it back up and it is ok, and then it goes down again.

 

[B. Diddy]

Which music app are you using? Do you have any power saving modes turned on, or 3rd party battery-saver apps installed?