Help! My Mac Keeps Waking Up!

August 18, 2011, By Christian Cawley

When you switch off your computer, you want it to stay off, but this isn’t always the case. For some people, Mac computers can switch back on, whether they have been put into sleep mode or shut down entirely!

There are different fixes that can be used to resolve this problem, from fixing your energy preferences to clearing them out entirely. Meanwhile, USB devices could be to blame for waking you Mac.

Fortunately these fixes are simple to implement, and by following them you should soon find that your Mac forgets to wake up at the wrong time and finally gives you a good night’s sleep!

Help! My Mac Keeps Waking Up!

Energy Saving Options

The first place you should be checking to get to the bottom of why Mac OS X is waking up is the Energy Saver preferences, available in Settings. Here you will find different settings for the computer and the display, with sliders determining when they should go into sleep mode when not being used and check boxes for putting the hard disk drive to sleep or reducing brightness on the display before it goes to sleep.

You may need to click the lock in the bottom left corner and enter your password to make any changes, but once you have done so you should find that any changes you make here are now saved and you can finally get a good night’s sleep.

Clearing the Schedule

If the basic check on waking and energy settings doesn’t work, you will need to take a slightly different approach. One way is to delete a couple of PLIST files, but this method is far tidier and much more effective.

Return to the Energy Saver screen and click the Schedule… button. If the Start up or wake checkbox isn’t clear, then you have found your problem already. However, if this is all empty we can make a few changes to force home the fact that you would like your Mac to allow you to have a good night’s sleep without worrying about whether it is going to switch itself on.

Put a check in the Start up or wake box, and then alter the time to read 00:00. Click OK to save the change and then reopen the Energy Saver preferences, return to Schedule and remove the check from the Start up or wake box, forcing the setting to clear.

USB Waking Up Your Mac?

Any number of USB devices can cause a computer to wake up when they find themselves losing power. While a mains electric-powered device such as a printer is unlikely to do this, anything without its own power supply (or with a low battery) will cause this to happen. As such you should make sure you have unplugged all of your USB devices before shutting down the computer if the fixes above don’t work.

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