Why my iPhone vibrates for several seconds everyday at 12 O'Clock? I am not sure if I am the only one who is facing this problem, but interesting thing is that my Iphone 5S(IOS 10.x.x) vibrates everyday 12 O'clock for several seconds and there is no way I can stop it. It is really annoying at work place. I checked if I have any alarm for 12 O'Clock, but I did not find one.

Any clue does it happen and how to stop it? Thank you in advance!
It could be anything from an alarm, to push notification from an app you have installed.  The best way to find out what it is, is check your Notification Center.  Pull the bar at the top down to see all your recent notifications. You should be able to see which one happened at 12 noon and take it from there.