Mac will not stay in sleep mode

One other thing to check are external drives. I have noticed that some external hard-drives, notably USB ones, which are in standby will come out of standby as soon as the Mac tries sleeping, waking up the Mac again. In this scenario you need to tell the Mac to go to sleep a second time. If that doesn't work, try unplugging the drive.

My computer would not stay in sleep mode either since update Mac OS 10.8.4 and I tried resetting the SMC.

Resetting SMC:

Shut down the computer

Unplug the power cord and ALL peripherals (mouse, keyboard + ethernet cable also)

Wait 20 seconds

Attach power cable and wait another 10 seconds

Press power button

Attach all other cables after desktop appears.

Try it if you haven't already. It cured the sleep issue on my iMac.

uncheck the wake for network option or restore your setting on defaults by clicking on "restore defaults"

then see

if this work for u or not......

thnxxx 🙂

Marks33 suggestion fixed the problem for me. Thank you.

I think you should use PleaseSleep. I've got the same problem. I don't know why my Mac mini (running Lion) can't auto-sleep after downloading and installing some updates like Java, iPhoto, iTunes...So I chose PleaseSleep.

Looking at system.log 10.8.5 I see that Time Machine and itunes seem to run (among others). Do I have to turn Time Machine off for the night if I want my mac to sleep?

I found that I had bluetooth sharing enabled. I disabled it, don't need it, and my problem seems to have gone away.