iPod Touch Battery Draining.

So I got an iPod Touch in March I believe and I loved it.
Recently however I have started having a problem. It seems that the battery is draining at an accelerated rate even when it is in sleep mode. For example when I go to bed at night the battery will be completely full and charged and when I wake up in the morning it will be completely drained. I don't leave it plugged in at night or on or anything.

I was wondering what the cause for this might be and how I could fix it.

Thank you.