A few Mac users have recently been complaining that their MacBooks/Pros/Airs keep waking from sleep. The end result is that when they do want to use them again, perhaps the following morning, their batteries are partially discharged – more than they should had they remained asleep.
Sleep itself can be prevented by the following:
- Network activities which wake the Mac (see below).
- Processes which prevent sleep. You can discover those by opening Activity Monitor, switching to its Energy tab, and clicking once on the head of the list Preventing Sleep. Processes listed as Yes at the top will prevent your Mac from sleeping, and need to be quit for that to occur.
The following events and activities can wake a Mac which is already asleep:
- Network activities which wake the Mac, including various types of sharing. Check the Sharing pane doesn’t make that Mac a ‘server’ for any of these, and disable Wake on Demand (see below).
- Notifications (see below).
- Bluetooth activity, typically other Bluetooth devices trying to connect. To fix this, open the Bluetooth pane, click on the Advanced… button, and uncheck the last item, to Allow Bluetooth devices to wake this computer.
- Opening the lid of a recent laptop model or connecting it to mains power, which automatically wake it.
Apple explains in detail the Wake on Demand system which allows connecting clients to wake a sleeping Mac which is sharing to them, in this article, now sadly archived. In addition to ensuring that your Mac isn’t offering a sharing service which could wake it up, open the Energy Saver pane and uncheck the item Wake for network access.
The most common problems now are notifications, which seem to come from every man and his dog, many of which don’t appear entirely under your control. The better apps are listed in the Notifications pane, but when you view their settings, there’s no control to suppress or mute them during sleep.
The best way to ensure that your Mac doesn’t get woken up by notifications is using the Do Not Disturb (DND) settings at the top of the list at the left. Tick (enable) DND to be turned on:
- When the display is sleeping,
- When the screen is locked (10.15 only),
- When mirroring to TVs and projectors.
Ensure that the bottom two boxes are unchecked, or they will allow your Mac to wake for:
- calls from anyone,
- repeated calls.
Then all notifications should be suppressed when your Mac is asleep, except for those of Find My Mac, which you do still want to work.
If your Mac continues to wake when it should be asleep, then the only reliable way to establish what is happening is to browse your log, using Consolation 3 to identify the event which caused it to wake. If you don’t know exactly when that happened, that can get tedious.