I usually don't post this sort of stuff until I have my facts right and I believe that I'm doing everything right to prevent the drainage.
So, let me explain.
I'm currently running the stock ICS 4.0.1. and considering moving to the MoDaCo custom ROM that Paul kindly made.
But I've noticed that from a full charge, and i go to sleep overnight that my battery drains to about 79% when I wake up 6 hours later, all I'm doing is setting an alarm for the following morning.
Here's the weird thing, I looked in the battery graph that shows the behaviour of the battery, and it seems my phone is ALWAYS awake, and my screen on time its just a little spec on this graph whereas the awake time is taking up 3 quarters. I had no apps running when I went to sleep, my screen is on full brightness using Paul's auto-brightness fix.
This has happened 2 days in a row, I'm wondering, is it just me or are the other people using the Nexus having this problem?
Let me know.