I've been running my iMac from an external SSD drive connected via USB 3.0 for the past 6 months. A few times, most recently on Thursday this week, I've put the mac to sleep instead of shutting it down entirely. Moving the mouse this morning woke it up with all my applications from Thursday still open. I wouldn't usually worry if it was running from the internal HDD but given that the Mac is running from the external SSD, is there a risk with putting it to sleep over shutdown?? (excessive weardown etc...) Also, how exactly is it managing to sleep if sleep mode is supposed to cut all power to the USB ports?