Trends

Do any of you notice trends in your PPC/CPA programs? Yesterday, I had a $30 eCPM. A 5% CTR, today...$11 eCPM and 3% CTR. WTF? This is all adsense stuff of course...but I was wondering...have any of you noticed what factors only the universe controls? Do you get more clicks on Sunday vs Friday or Mondays? How about full moons? What I'm getting at here ... is it just fate or are we being manipulated? I know it must be both...so, if you have noticed trends in your earnings or patterns in your users? If so, what?