IPhone keeps restarting over and over by itself?

About the phone:
- iPhone 5S
- 5 months old
- iOS 8.3
- EE network

So basically, my phone keeps restarting constantly by itself, I don't know if it's that trick thats been going around where if you send some text to an iPhone user, it'll restart, my brother whose got an Android tried doing it but it didn't work and it's only now worked but other than that, it just won't stop restarting, I picked it up, it restarted, after waiting so long for it to turn on properly, 5 seconds later, it restarted, AGAIN! It's only started yesterday, help please?

That message bug only happens if you have banner notifications on, turn that off until they release a patch.

  • My iphone keeps restarting itself alone has full battery? My i phone (i think 3 generation has camera in front) keeps on turning white and restarts itself has battery i'm not doing anything.plus when it restarts it just show my slide bar but the screen of my iphone turns dark then bright then dark then normal as i had set it. I did not jail break it.
  • My iPhone 4S keeps turning off over and over and over again? I was on my phone just listening to OM&M on pandora and going on twitter when all of a sudden it shut off and now it's stuck on the turning off screen for like an hour or two. What do i do I'm FREAKING OUT.
  • My iPhone 4S keeps restarting itself? Earlier on today, my phone died at 40%, when I switched it back on whilst charging it (took around 20 minutes) it was on 6% and then died, I charge it again and it was really low. I left it for a while and it went to 60% and mysteriously to 53%. Now it keeps restarting, I've tried doing the hard reset (holding the power and home button) but I've had no luck. Why is my phone doing this and how can I solve the problem?
  • My iPhone 3GS has been randomly restarting itself The screen goes blank then the Apple logo appears, after a few seconds it returns to the home screen and whatever I'm doing is lost. It has been doing this every couple of minutes all day yesterday, then this morning it suddenly returned to normal. What caused this and how can I diagnose/repair future issues? The phone is switched off all night and it started when I switched it on yesterday morning.