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

I haven't read through all posts, but it's nice to know I'm not alone... I used to have this problem regularly, but now far less so since following the following procedure to put my iMac to sleep...

I have a 2006 vintage iMac running Tiger (must upgrade soon, but its still a great work-horse) with the new style wireless keyboard (so nice, I almost wanted to buy a new iMac that has it as standard!) and the older style (1st generation?) wireless mouse.

I use the setting to allow the power button to put my iMac to sleep and I consistently use this rather than choosing "Sleep" from the Apple menu. Procedure I follow is:

- Logout
- When I arrive at the Login screen, press Power button to send iMac to sleep
- Switch off mouse

For a very long time, following this procedure has allowed me to restart by pressing a key on the wireless keyboard. Before, when I selected "Sleep" from the Apple menu, it required the "hold down the power button to switch-off and restart" workaround.

Has anyone actually has any iMac quod core sent back to Apple and actually has it returned with this sleeping problem fixed? My own solution is shutting down mine every time I am off my iMac! Very troublesome.

Since I wrote in about this problem, I've not had this problem. Don't ask me why, since I do no know but I do hope this continues. I just don't get it.

Hi guys,

I'm having the exact same problem. At least I know I'm not alone. I have a 21.5" imac, 3 months old. It's even going to sleep when I'm in the middle of browsing the web.

So frustrating.

Any new news on this issue?
My 1 year old imac just started having these issues as well:
-won't wake from sleep sometimes, just low-level fan noise
-bluetooth keyboard is often "lost"
-computers starts up but stays at the spinning mac screen or the blue screen
-starts up fine but won't register bluetooth keyboard or bluetooth mouse

Not exactly happy about any of it; at least it will work again once powered off and then started up again, but it makes for an unhappy and frustrating time.

Hello, Same problem with me... My Imac don't wake up from sleep and I have to shut it down and of course loose my work ;-(
VERY frustrating...
Might be time to test working with PC again.

Apparently, even the new july 27th 2010 models do not solve this problem. We just got in a 27" / 2.8GHz Quad-Core Core i5 / 4GB / 1TB / ATI Radeon HD 5750 inch model in yesterday afternoon for the lab and it started "now wake after sleep" on day 1 just after transfering info from our previous G5 powermac. This model was loaded with 10.6.3 I believe.
Called Apple, they are sending out a replacement.
Not very comforting though! Suggests they really do not know what the problem is
(or that its rare enough that they have decided not to deal with it)

Imac 27, same issue. Usually Apple is good about fixing the issues but this seems to be dragging. At times, I think changing the batteries in the mouse helps. But my prob is so sporatic, I cannot rely on that.

Everyone, if your batteries are below 70%, change them and see if that helps!

Well, for what it's worth:

I also partially subscribe to the heat theory, I've had this problem on and off for the last couple of years - but usually only in the Summer months.

I've got a 2006 20" iMac, currently running Tiger. I recently replaced the original hard disk with a new Samsung Spinfire F3 1TB disk, as someone had suggested it may be the hard disk failing, but alas this has made no difference. I've also purchased the upgrade to Snow Leopard hoping this might solve the problem, but have not yet installed it and from the sound of the posts here, it just as prevalent in 10.6, so may as well not bother.

I used to always hold the power key until it shut down, but I've found as with others, that if it doesn't wake on keyboard or mouse, if i briefly push the power button, it sends it back to sleep, after which it will wake up using keyboard or mouse. A pain, but not as bad as shutting down and starting up again.

It is a strange one, and certainly rare that no one has found a true across the board cause/solution. As we all do, I also hope Apple are following this thread and pull their finger out to solve this problem. I was thinking about upgrading to the new i7 2.93 Ghz imac this year - because of the age of the machine and the wake from sleep issues, but I don't see any point, if the latest machines are also suffering.

Come On Apple!!

May as well add my name to this list, 3 months of use and problem started.

I had the same problem with a refurbished 27" iMac I purchased recently. I tried all the solutions listed here in this thread including removing usb stuff, the pram reset thing, erase install, nothing worked. Now I have a new computer and it seems to be acting properly.

Is this still not fixed yet?! I just got a new 21" iMac with a bluetooth keyboard and a Magic Trackpad and I have this same problem: When the computer goes to sleep, I cannot wake it with the keyboard or trackpad. I have to tap the power button, wait a few sec, then tap the power button again, then it will wake up.

This is interesting: Apple has reportedly seeded a new software update called "Snow Leopard Graphics Update" to developers. While the exact focus of the update in testing is unclear, it appears from the areas in which developers are being asked to focus their testing that it addresses several aspects of graphics performance including VRAM utilization and hot-plugging and *+wake-from-sleep issues+*. The general release notes claim only that the update addresses reliability of "graphics applications and games". macrumors.com

Sounds like it might be software-based.
Since I do not see the checkbox "Allow wake-up via bluetooth" grayed, I would assume that my Bluetooth is working just fine.
When I send my mac to sleep manually, waking it up via mouse or keyboard is usually possible without any probs.
The described issue only occurs when it was sent to sleep automatically. In these cases, I apply the "hold Powerbutton for a few secs (maybe 4-5)" trick and then press it again a few seconds afterwards.
I will now hope for a graphics driver update that hopefully fixes that problem.

Try this, it worked for me:

To solve this problem, follow these steps:

1. Go to system preferences and select 'Desktop & Screen Saver'.

2. Set the start time for your screen saver to a desired amount.

3. Go back to system preferences and select the 'Energy Saver' preference pane.

4. Set both the 'Computer sleep' & 'Display sleep' times to less than the 'Start screen saver' time amount. This will ensure that your screen saver always starts before the iMac goes to sleep.

By following the above steps you will then be able to wake your iMac from sleep by using your keyboard or mouse/trackpad.