Changes you made in the notification center, in my opinion, would not have that kind of drastic effect on your battery life. So I think we can rule that portion out.
Email is a tough one...the problem is that even email fetch and push settings should not effect battery life like that, but an email fetch that gets stuck (perhaps due to a bad network connection) could put a big drain on the battery as it will sit in a loop trying to complete the task of fetching emails. This SHOULDN'T be happening, but it's possible (and would be more in line with checking connection to the cellular/WiFi network than it would adjusting anything the iPhone is doing itself).
...if you want a fool proof way of getting back to square one, do a restore. Connect your device to iTunes and make sure you have a recent backup. Again, I don't see either of those adjustments you claimed to have made being the issue here, but anything is possible. A restore would also (theoretically) fix any weird performance issue you may be having with an app draining battery life as well.