英语翻译W:You've been sitting at the computer for hours. Let's t

英语翻译
W:You've been sitting at the computer for hours. Let's take a coffee break, shall we?
M: I wish I could. You know, I'm up to my neck in work. I've got to finish this report. I don't want to miss the deadline.
I'm up to my neck in work是什么意思？