It is there already. This is implented in the 'MONyog API'. Please refer documentation, and scroll down to 'The MONyog API'.
You will need a scripting/programming environment that can send (simple) HTTP requests (what I cannot think of any that cannot) and schedule two script/apps – one stopping and another restarting alerts.
Code:
Enables alerts for
http://:/?_object=ConnectionMgr&_action=ConnectionAPI&_actionvalue=EnableAlerts&password=&server_name=
Disables alerts for
http://:/?_object=ConnectionMgr&_action=ConnectionAPI&_actionvalue=DisableAlerts&password=&server_name=