How do withdrawn courses in my transcripts affect my PhD admissions application? I'm currently finishing up my masters degree and hoping to apply to quite a few good PhD programs. I've gotten perfect scores in all my classes thus far as a graduate student and as an undergraduate, I got perfect scores in my major classes.

I'm currently taking only one class because I'm working full time (and I've taken all the graduate courses in my field already (at my current university), so there isn't really much left for me to take), and it's taking it's toll on me quite a bit (I'm barely sleeping, constantly stressed, anxious, etc.). 

I'm considering dropping the one course I'm taking, but it's halfway through the semester and I would end up receiving a W (withdrawal) on my transcripts. I plan to leave my job at the end of the semester, so this shouldn't be a problem in the upcoming semesters.


How does having a W on ones transcripts affect PhD applications? 
How do admissions committees look at it? 
Any advice to students in a similar position as my own?


Note: I've read this post with a similar title, but it doesn't directly address my concerns; it's primarily asking about the proper protocol to follow when sending transcripts; in this case, the transcripts will be sent regardless.
I've been heavily involved in graduate admissions at a top-20 program for many years. A single withdrawal never bothers me; I realize that life happens. It's when they start to become common across a transcript that I start to worry.