Putting your iMac to sleep mode at night is vital to ensure it performs background tasks such as basic clean-up. Sleep mode also conserves battery power. However, you can wake up to the surprise of a whooshing sound from your device waking itself.
So, why does my iMac turn on and wake by itself? An iMac can turn on and wake up by itself without any of interaction due to a problem with its settings. Where the network, Bluetooth, USB or operating system settings, can send incorrect signals to the iMac and wake it up from sleep mode.
Sleep mode serves you when you want to conserve your battery without shutting down your device completely. When you put your device on sleep mode, it will be on standby with components like storage drives, processor, and memory. Hence, waking up from this mode will interfere with or interrupt some of these processes.
Your iMac will go into automatic sleep mode as long as you are not using it. Usually, this will occur after two minutes of inactivity, and when this happens, it will conserve your battery power. You do not want to wake to a low battery message as this can be inconvenient if you plan to be out of your home for a better part of your day.
Putting your iMac in sleep mode is convenient to save power and preserve your workflow. You can set this up in the Energy Saver system. The system should remain in sleep mode unless you command it to wake.
However, your system can randomly wake from sleep, which can irritate you from the whooshing noise, not to mention its effect on the battery power. It may even be more concerning as you wonder whether someone is accessing your system unauthorized. Read on to understand why your iMac turns on and wakes by itself.
Your iMac will turn on and wake up by itself due to a problem with the settings. These include network settings, USB, and Bluetooth. Hence, by adjusting some of these settings, you will fix most of the settings. Still, if this does not work, it could be because of another problem requiring further interventions.
If your iMac turns on and wakes up by itself, start checking the sleep settings. To do this, navigate to the Apple Menu, then select System Preferences. If this does not fix the problem, it is time to investigate other potential causes.
An iMac can also wake up due to some network activities. Examples of network activities that can turn on the wake-up feature include a photo, printer, iTunes, and file sharing. Using the Back to My Mac feature will also turn on the wake-up feature.
Finally, your iMac will wake up in the middle of the night due to an active Bluetooth activity. You can stop Bluetooth from waking your device by navigating to the Apple menu:
- Select System Preferences
- Click Bluetooth
- Advanced
- Deselect the “Allow Bluetooth devices to wake this computer”.
If you suspect your USB devices are causing your iMac to wake up, unplug them one by one, plug them back, and check for any effects to rule the device as the reason behind the waking.
Why Does My Mac Wake Itself Up?
Users online complain that their Mac wakes itself from sleep, and the result is a partially discharged device, which would not have been the case if these devices remained asleep. Read to understand what could cause your Mac to wake up from sleep mode.
Your Mac PC will wake up randomly due to network activities that turn on the Wake on Demand feature. These activities include file, printer, photo, and iTunes sharing, not to mention using the Back to My Mac feature. Notifications from Messages, FaceTime, and other apps and services may also cause your device to wake up by itself. Activities from Bluetooth devices like your wireless mouse will also prevent sleep.
As stated earlier, several processes can prevent your Mac from entering sleep mode, and discovering these processes is not straightforward. To discover the processes causing your Mac to wake up, navigate to the Activity Monitor, switch to the Energy tab, and click the head of the list Preventing sleep. The processes that prevent your Mac will appear as Yes, and you will need to quit them to stop them from waking your Mac.
If you connect your Mac to the internet, it can wake up randomly due to internet activities, especially if you connect your Mac to a network drive or server in your home. An active network drive will send a command to your Mac and wake it up.
If you share your Mac resources such as music, printers, iTunes, or other files, it will wake itself from sleep as other users try to access them. Your Mac waking up from sleep is a way of communicating to other users that these resources are available.
The notifications that can wake your Mac include iMessage, Game Center, FaceTime, Find My Mac, and social media notifications from LinkedIn, Twitter, and Facebook. While you may need to know when someone calls or messages you, these notifications could be a nuisance, especially if they wake your Mac in the middle of the night.
Applications such as amphetamine will prevent your Mac from sleeping even when you close it. This is even though using your Mac while closed is ideal if you are using it with an external display. If your Mac is waking up at night against your wish, check the external display for Apps that could be causing this. You will see the apps at the top right of your screen.
For a while, Apple included infra-red sensors in its Mac for controlling the Front row and some applications. However, this feature is no longer present in modern Mac systems. Thus, if you are still using an old system, it may wake from sleep due to infra-red activity, in which case disabling the infra-red sensor should resolve the issue if you do not use the remote control.
If you use the remote, ensure you pair it with the system. Generally, your Mac does not feature a remote controller, and you can use any remote device. Pairing your Mac with a remote allows it to respond to the specific remote and ignore infrared activities that can wake it up from sleep mode. To pair your remote, navigate to Security and Privacy System Preferences, click the Pair button and follow the onscreen instructions.
How Do I Stop My Mac from Automatically Turning On?
Now that you understand why your Mac is turning on unexpectedly, it is vital to know how to prevent this activity. Read on for all you need to know to stop your Mac from turning on automatically.
The first step to fixing the Mac turning on automatically from sleep is to check the sleep settings and ensure they are the way you want. Other things you should check include the system’s network access setting, sharing preferences, system activities, software or SMC, and other unexpected functions that may trigger your device to wake up.
Navigate to the Apple menu to view and adjust your sleep settings, then select System Preferences. If you are using a Mac Notebook computer, click the Battery icon then Power Adapter. To set the time that should pass before your PC goes into sleep mode, drag the Turn display off after.
Alternatively, deselect the Prevent computer from sleeping automatically when the display is off. On the other hand, if you are using a Mac desktop PC, click the Energy Saver and drag the Turn display off after to set the amount of time that should pass before your device goes into sleep mode.
According to Apple, sharing resources such as iTunes, photos, and Music playlists will cause your device to wake up from sleep as other users access these resources. Hence, by Stopping all file-sharing activities, you will also stop your Mac from waking up in the middle of the night. Therefore, navigate to the Apple Menu, System Preferences, and then Sharing to turn off file sharing. In the Sharing window, uncheck the options under the Services tab to prevent your Mac from sharing files.
If notifications wake up your Mac, you can control them by navigating to your Apple Menu, System Preferences, and Notifications. From here, select the notifications you want to wake your Mac and disable the rest.
Alternatively, you can use the Do Not Disturb feature, which turns on automatically as long as you connect your Mac to an external display. This feature silences incoming notifications and calls.
You can choose when the Do Not Disturb function turns on and off by navigating to the Apple menu, System Preferences, and Notifications. While on the Notifications window, the Do Not disturb settings will be at the top of the sidebar.
While in the Do Not Disturb mode, you should note that you will not receive any notifications on your Mac. Hence, if you want alerts for work, turn this feature on when you are awake and do not mind the disturbance from frequent notifications.
Bluetooth devices like your mouse or printer can also wake your Mac, and you can stop them by navigating to the Apple Menu,
- System Preferences
- Select Bluetooth
- Select the Advanced option
- Uncheck the Allow Bluetooth devices to wake this computer option.
- Tap on the Ok tab
- Close out of this window.
While a Bluetooth device can turn on your Mac, it should go off two minutes later if there is no activity ongoing, but the best way to prevent the frequent wake-up is by turning off the above setting. Pets can also trigger your device to wake up if they press your keyboard or mouse.
To find out if your USB or Bluetooth devices are waking your Mac from sleep, you should disconnect or unplug all of them from your Mac and wait for your Mac to go into automatic sleep mode. If it does not wake up from sleep mode this time, it is safe to rule out that the USB devices are the culprit.
If you have more than one device connected, the best way to establish which among them is causing this waking is by plugging one USB device at a time. Malfunctioning keyboards that keep sending information to your device will prevent it from entering sleep mode, not to mention a pressed-down mouse key.
If you try all the above ideas, but your Mac still wakes up, you have no option but to reset the SMC. The Mac power manager controls the sleep mode. This power manager, also called the System Management Controller, SMC, stores options when your device is in sleep mode, among other Mac features.
This information can get corrupted, causing random wake-ups. Hence, you can reset your SMC, update your MacOS, or use safe mode to fix this problem. Resetting your SMC will solve most of the power-related issues.
If you are using Mac with Apple silicon, restart your PC but if using other Mac PCs, put your Mac to sleep, wake it afterward and restart. You can then wait for it to boot up and shut down completely.
After that, plug in the charger and press the Shift, Control, and Power button at once, hold for a few seconds, release them simultaneously, and turn on your Mac. If you power your Mac via a power cord, you will shut it down, unplug the power cord, wait for a few seconds, plug the cable back, and wait and turn on your Mac. Updating your macOS will resolve specific issues, while the safe mode will help you determine if the wake-up results from a software loading when you start up your Mac.
Finally
Your iMac or Mac will enter sleep mode with a certain length of inactivity. When this happens, only minimum activities will occur, consuming your battery. As such, you will wake up with your battery a little drained, which can be inconvenient.
Among the reasons your iMac or Mac will wake up from sleep mode include network settings, system activities, Software or SMC issues, sharing preference, Bluetooth connections, and USB triggers.
The first step to fixing the Mac turning on automatically from sleep is to check which of the above settings is causing your device to wake up and address the issue independently. This way, you will be in more control of the cycle your device wakes up from sleep mode.
