Haswell 10.11.4 won't fully sleep and won't wake

When I sleep my machine or it goes to sleep by itself, the display sleeps, but the machine does not sleep; the fans continue spinning. When I try and wake the machine from this sort-of-sleep with either my USB mouse or keyboard, the mouse and keyboard both respond by illuminating, but the machine does not wake. Pressing the power button on the tower also does nothing.

I have to hold down the power button on the tower to hard shutdown and then boot back up, but I get no crash reports after...

Haswell 10.11.4 won't fully sleep and won't wake