Yosemite install caused sleep disturbances.....
Installation of El Capitan hasn't resolved the "issue", best described here: http://tinyurl.com/MBPWakeupnoise
Prior to installing Yosemite, back in May '15, my mac didn't do this. The noise doesn't concern me, it's just the prolonged "back and forth", having to continually prod the touch pad and push the power button, all things I didn't need to endure previuosly, create unnecessary delay before I can get back to work