Default Bluetooth keeps turning off

I've just started having issues with my Bluetooth turning off. Not sure if some app has caused it or.something else. Any ideas? Its annoying as I have to keep turning it back on.

--==SONY XPERIA Z ULTRA FAN SITE==--
Current devices: Sony Xperia Z Ultra, Sony SmartWatch 2, HTC Sensation
Most recent past devices: HTC One X, Samsung Nexus S, HTC Magic