Q: iMac won't wake up from sleep using keyboard or mouse

I think I can help put this to rest...

Click the Bluetooth icon in the upper right.

Click "Open Bluetooth Preferences"

Click "Advanced" settings button in lower right of window.

Check box "Allow Bluetooth Devices to wake this computer"

I think for some reason, one of the OS updates un-checks this box. Simply re-enable it and you're set. This worked for me after having this issue for a few weeks.

I'm sorry I'm so dense but where is this 'Bluetooth icon in the upper right?' Thanks.

Randall De Trinis1 wrote:
I'm sorry I'm so dense but where is this 'Bluetooth icon in the upper right?' Thanks.

System Preferences>Bluetooth and put a tick bottom left 'Show Bluetooth status in the menu bar'

Click "System Preferences" then click "Bluetooth". Same result as the Bluetooth icon on the menu bar.

Proceed with clicking "Advanced..." and checking the indicated box in my previous post. Hope this helps.

I have the same problem and your solution is irrelevant as the "allow bluetooth devices to wake this computer" was already checked.

The apple store had my computer for two weeks, ran all sorts of hardware checks --nothing wrong. They told me to just shut the computer off each night. But I should not have to do that.
This morning it again would not wake up without a hard shut down and power on. I think it is a firmware problem that Apple just has not found a solution for yet. I have all latest updates and Imac is brand new.

same here. my iMac would not wake up without a hard shut down and power on. hope there will be a solution soon.

My new Mac Mini 2010 worked fine when it arrived a couple weeks ago. After migrating my 10.5-based apps and data, I got the not-awaking-from-sleep problem. In my case, it's almost like it shuts down automatically, since tapping the power button immediately causes a system start. I reinstalled the original 10.6.4(?) system, it worked fine. This time, I decided to migrate software incrementally. Started with my Mail folder. On opening Mail.app, it insisted on IMAP access to my gmail account. I canceled this, restored the system, and copied my older keychain.login (after validating or checking or whatever from within the Keychain app), with the POP gmail access. Mail worked fine. However, the sleep problem returned. I repeated the process (restored system, worked OK; updated keychain, this time without even launching Mail. Sleep problem was back. Restored original system again, worked fine. Copied the Mail folder and just the 2 older keychain items needed for my Pop and SMTP mail login; again, I didn't even run the Mail app. The sleep problem returned.

And that's what I plan to do with the Mac--return it! I've been a Mac user, nay, enthusiast, since the SE, and have NEVER had these kinds of issues. I'll get an older system that'll work fine with 10.5, and am actually looking into Windows 7, which works (and looks) pretty nice on my computer at work.

Sorted my issue by exchanging my Mac - genius report found an issue with the EFI if that helps anyone

Want to add myself to the 21.5" new iMac won't wake list.
I spent yesterday reinstalling the OS from the install disks that came with the machine (4 weeks ago!)
then updated with the most recent iMac 10.6.4 update.
uninstalled every non-Apple kernel extension I can find except for a Microsoft keyboard (newest driver installed; same keyboard in use on a MacPro without problem).
Reset SMC, PRAM; checked Bluetooth "allow to wake" setting... already set.
have tried the "allow power button to put machine to sleep" both yes and no --- no difference!

I know it's a new machine... but come on! How about some attention to detail to Mac OS --- not just iPhone!

Now in addition to the not waking up from sleep problem, my 1 year old 2.4 Ghz Intel Core 2 duo imac is often freezing on startup.
It happens almost every other time I start it up. It freezes anywhere along the way between turning the computer on and when the main screen appears.There will be no response to keyboard or mouse, and the computer clock stays frozen at the time that it comes up.
Anyone else experiencing this as well as the not waking up from sleep issue?

I've tried everything suggested on here as well and nothing has helped. I don't have time to take the computer in and hope that Apple can fix something, and so I'm living with the problem of having a great piece of hardware that doesn't work all the time. I've had apple computers ever since owning an Apple II and never had a problem like this until now. Grrrrrrrr.....

I am now on my third 27" iMac which will not wake up when it puts itself asleep. I have to unplug it, hold the power button for 10 seconds and plug it in to get it to start up again. Apple has replaced them every time. Nobody at the Genius Bar or Apple Care can help me by diagnosing this problem. This has happened twice to brand new machines; one would not wake up no matter what we tried. I used my current machine for a few weeks before it started to do it too. Apple Care assures me that it is not me. At their suggestion I have replaced my APC surge protector with a new one. They tell me it is not a software issue because when it was suggested that I partition the HD and reinstall OS 10.6.5 it still does it (as it did with 10.6.4). I have to say that Apple has been willing to replace the machines but I am now getting frustrated due to lost productivity and hours of lost time bringing it back to the Apple store.

There seem to be a number of different problems (and suspected causes) being discussed on this thread. But at least for me, the update to OS 10.6.5 solved my problem, at least for the past few days. So in my case it was "just" a software problem?

It's apparent from this thread and many others that this is an issue that is endemic with iMacs and ATI graphics cards. I personally do not think this is a manufacturing defect. The key sequence ctrl-shift-eject is the hotkey shortcut for toggling sleep mode. It seems that the graphics card does not wake from sleep consistently and toggling sleep mode when the display is off works. Since this issue does not appear in Windows running under bootcamp one must assume that it is driver software related and not a defective mac. My experience with ATI drivers has never been pleasant.

When the display does not wake from sleep:

1. press "ctrl-shift-eject" (wake from sleep)
2. press "return"

Furthermore, to my previous post... It's possible to cure this (in some situations) by resetting both the PMU (Power Management Unit) and the PRAM.

1. To reset the PMU:
a. shutdown the mac
b. remove the power cable
c. wait 15 seconds
d. hold the power button down for 5 sec then release
e. plug in power cable
f. Turn on

If the fan is running at high speed continuously on boot up then the PMU has been erased instead of reset (which is not good). This can be remedied by repeating the above steps which will restore the PMU firmware. Usually this happens when the above procedure was done out of order

2. Reset PRAM (NVRAM)
a. shutdown (i.e. turn off power)
b. turn on mac then
c. immediately press option-command-P-R keys simultaneously
d. continue to press until the screen recycles for the second time and you hear to boot-up tone
e. release the keys to continue the bootup

Have same problem here with an iMac (summer 2010) that gives me the spinning wheel for hours, if I do not not re-start it with the power button or pull the plug.

I have tried your advice several times, but it has not helped lately.

Will a fresh install of the OS help? - Or will a erase and install from scratch be better (using the combo updates)? (Until Apple comes up with a kind of update for this).

Message was edited by: John Christiansen