Why am I using data in the middle of the night when I'm sleeping and have wi-fi anyway

[DasB00t]

My date usage shows activity when I'm not using my phone, very small usage but usage never the less. unacceptable when you are charged for overages

[Loquat · Accepted solution]

I have the iP6+ and I'm connected to WiFi when I'm actively using my device.  I do notice once I put my phone to sleep that my WiFi signal will disconnect as indicated by the status light on my modem.  During the time my phone is sleep/screen off, I still get notifications of incoming emails, facebook, etc.  My WiFi signal doesn't connect again until I manually wake my device by touching the home button.  So, any of the emails or app notifications that come through while my phone is sleep still uses cellular data...not very much...but data usage nonetheless.  I'm not sure this is what's happening in your situation...just trying to shed some light...

[DasB00t]

That's probably it / Thanks