Answer to: Why does my phone keep vibrating for no reasonA vibration is oftentimes used to notify you of an event, usually an alert. In my case, when this happened frequently on my wife's phone, I did some snooping and realized that she kept getting a notification of available Samsung Software Updates. At times, the notification would pop up on the notification bar, at times, it would not. I did the updates as per the notification and have not had the phone vibrate ever since. So snoop around and see whether any of the default apps, or the installed apps need updating and this may just be the thing causing you sleepless nights. Regards, Kevin.