Many iMac users have to put up with constant reboots from their machines, and you will find them complaining in tech forums that “iMac always reboots on wake-up”. This is not only annoying but also an unnecessary problem that, for them, shouldn’t exist in the first place. The Mac sleep mode problem, as it is often called, means that leaving your computer running while you attend to something else risks losing unsaved data and interrupting running programs and can be a real drag on anyone’s productivity. What’s more concerning, however, is that pressing the spacebar to reactivate the display is what often triggers the restart mode, which makes users feel that they have little or no control over what happens with their computers.
Why does IMac reboot on wake-up?
Apple notes that the sleep and wake behavior of the Mac is affected by many things such as systems settings, activity from apps, the network it is part of, and the connected devices. To therefore solve the problem and to prevent your Mac from restarting after waking, one needs to look at all of these things and more, and for that reason, a number of solutions have been recommended.
Solving Mac restarts after sleep problem
If your Mac restarts after sleep instead of waking, you should first make sure that the Energy Saver is set to the right preferences. To locate the Energy Saver on your Mac, go to Apple > Menu > Systems Preferences and then click Energy Saver.
Some of the controls that may be affecting your Mac’s sleep and wakefulness states include:
- “Turn display off after” slider
- “Display Sleep” slider
- “Computer sleep” slider
Any of these sliders could be the culprit behind the unexpected behavior from your Mac. For example, if the slider is set to “Never”, sleep is disabled for that feature. This means that you can easily solve the Mac restarts after waking problem by setting the display sleep slider to “Never” for instance, although this will come at a cost to your battery. Alternatively, you could use the “Turn display off after” slider to increase the time it normally takes for your display to turn off after the computer is left unattended to for long periods; doing this will also affect how long your battery is able to last.
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Reset SMC
If the Mac sleep mode problem persists even after these tweaks, Apple recommends that you reset your computer’s SMC. SMC stands for System Management Controller and is responsible for most of the low- level functions of Intel-based Mac computers. Some of these functions that directly affect the sleep and wakefulness states of the Mc include:
- Responding to presses of the power button
- Battery management
- Responding to the closing and opening of the display lid in Mac notebooks
Whenever a problem of the likes of Mac restarts after waking is experienced, it is more likely the case that the SMC has lost a handle on some of its functions and needs to be reset.
How to Reset the SMC
Procedures on how to reset the SMC depend on whether the battery is removable or not and the type of Mac that needs to be reset. If the battery is non-removable, take the following steps:
- Choose Apple Menu > Shutdown.
- After the Mac shuts down successfully, press the Shift control option (left side of the keyboard) and the power button all at the same time for about 10 seconds.
- Release all the keys.
- Turn on your Mac again by pressing the power button.
If the battery is removable, the following are the steps to take:
- Shut down your Mac.
- Remove the battery.
- Press and hold the power button for about 5 seconds.
- Reinstall the battery.
- Restart the computer again by pressing the power button.
If you are using a Mac desktop (iMac, Mac mini, Mac Pro, and Xserve) that restarts after sleep, take the following steps:
- Shut down your computer from the menu option.
- Unplug the power cord and wait for 15 seconds before doing anything else.
- Plug the power cord back in.
- Wait for 5 seconds before pressing the power button to turn your Mac on again
For Mac desktop and notebook computers that run on the Apple T2 security chip, the following procedures are recommended:
- Shut down the computer using the menu option.
- Press and hold the power button for 10 seconds after the shutdown.
- Release the power button and wait for a few seconds.
- Turn on your mac by pressing the power button
If the above steps fail, start the following alternative procedures for both desktops and notebooks:
- Turn off your computer via Apple menu > shutdown.
- After the shutdown press and hold the power button for 10 seconds.
- Wait a few seconds after releasing the power button.
- Power your computer back again.
If the above procedure fails to restart your desktop repeat it in the following manner
- Shutdown your computer via Apple Menu > shutdown.
- Unplug the cord after the shutdown.
- Plug the cord back in.
- Wait at least 5 seconds before powering the computer again using the power button.
For notebooks, use the following alternative steps:
- Turn off your computer Apple Menu > shutdown
- After the shutdown, press and hold the right shift key, the left Option key and the left Control Key for about 7 seconds. Press the power button while holding on to these keys.
- Release all keys including the power button, and wait for few seconds before powering your Mac again.
If none of these solutions work, you can try a deep clean of caches using a cache cleaner, which also offers relief from the problem.