My iPhone restarts automatically when it's idle.

Hi Xiang He,

That's a new one on me; I don't recall seeing this particular problem before. Can you elaborate on what you mean by "gadgets"? Do you mean you've deleted and reloaded all of the apps you've added to the phone?

First thing, let's see if the phone logged any information when it rebooted. Read Alisha's (@flannelist) wiki page on Kernel Panics to locate any panic logs that might be on your phone.

iPhone Kernel Panics - iFixit

If you find any, pull up the most recent one and add a screenshot or a copy/paste of the first page or so to your question and we'll see if we can figure out what's causing it.

Otherwise the best way to eliminate software problems is to restore the phone back to factory settings. Do a full backup then I'd suggest a DFU mode restore; that's the most complete one possible. Try the phone out and see if it's still rebooting after that.

If so, we'll have to try and figure out if it's a hardware issue. Otherwise restore your backup and double check to make sure it doesn't start rebooting again. If it does, there's something that's been loaded on your phone that's causing the problem. You may need to start deleting apps until you find the source of the issue.

Give these suggestions a try and let us know what you find.