Did DST kill my battery?

[GoodGets]

I get in bed around 1:45 am and right before I fall asleep I hear a notification on my phone. I roll over and it says that due to daylight savings time, my clock has been changed. I checked the clock, it changed from 2:00 to 1:00. So I set my alarm back an hour as well. (I use alarmclock.WM2003, just a basic alarm clock program I found on the net a few years back. Never once caused a problem on this phone in the past.)

I did not charge my phone overnight. I checked it right before I went to bed, it had 85%. However, when I got up this morning, an hour late because my alarm didn't go off, the phone is completely dead. I put it on the charger. The LED flashes red a couple times then turns to orange. I turned on the phone and it said the battery now had 1%. WTF? What happened overnight? I did the same thing I did every other night, except for DST. Any ideas as to what could have caused this massive battery drain?