Hi cheecy,
Thank you for participating in the Apple Support Communities.
If your iPhone is restarting unexpectedly, first make sure that iOS, your iPhone apps, and iTunes are updated to the latest version:
If your iOS device restarts, displays the Apple logo, or powers off while you're using it - Apple Support
Make sure that your device is up to date and your apps are up to date.
Update to the latest version of iTunes - Apple Support
If your iPhone still restarts when you try to sync it, the article above suggests contacting Apple Support for more help:
If you still see this issue after updating, contact Apple Support.
All the best,
Jeremy