In reply to cmr132:
I use an iPhone in similar situation.
Emails are set not to alert (just badge the icon on the home screen) - although if you need specific emails to be more obvious, google the VIP function - it's a bit obscure but you can sort it.
Most texts are set to a fairly low key beep.
SARCALL texts have been set (though contacts, from what I remember) to the loudest siren you can imagine! This overrides the default, so I think the suggestion above of changing the default text alert to "none" overnight would do the trick.
Not sure if you can get anything to override the "do not disturb" function, haven't tried through that.