Do you get the feeling that your Mac is really slow to wake up from sleep mode? Do you see a black screen for a few seconds instead of the login screen after opening your MacBook’s lid and you don’t know why? Well, you’ve come to the right place, since we’ll explain why your Mac is slow to wake up and how this relates to Apple’s energy saving features built into macOS.
What Happens When You Leave Macs Idle for a Longer Period of Time?
You may already be familiar with the ‘short term’ energy-saver settings in macOS: which switches off the display and puts the hard disk(s) to sleep after a short period of inactivity. Things change when you leave a Mac idle for a long time. Some computers enter special sleep modes called standby and safe sleep, helping them conserve even more energy.
Standby saves the user’s current session – open applications, files and windows – on their hard drive. macOS will also turn off some of its hardware systems to save power.
Standby mode is limited to Macs that start up from an internal flash drive. These Macs enter standby after being in sleep mode for three hours, while earlier models enter standby after just an hour of sleep. During this deep sleep mode, the state of the user’s session is copied to the SSD and macOS turns off some hardware systems, such as RAM and USB buses. Standby mode extends how long a laptop can stay in deep sleep on battery power, which could be as long as 30 days.
Safe sleep ensures that data stored in the main memory of your Mac isn't lost when the computer shuts down due to its battery being completely drained.
Dumping Data From RAM to Disk
Mac standby and sleep work by dumping everything in active RAM into a file called ‘sleepimage’. This file is generally the same size as the amount of physical RAM your machine has under the hood.
This file is located on the hard drive. When your Mac exits standby, the system is restored to its pre-standby state when that sleepimage file is copied back from the hard drive to RAM.
Check This First If Wake Time Is Too Slow
If your computer doesn’t return to full operation within a few seconds, you should check the following: first (and obviously) make sure your Mac is actually powered on, as the battery could have been drained; have a look at screen brightness and adjust it; check that the external display (if applicable) is turned on. And finally, make sure the computer is plugged into a power outlet.
Another option to consider is that it might be in safe sleep, in which case you’ll need to press the power button to wake it up.
How To Speed Up Wake Time
If you have a Mac with a HDD, the hard disk and CD-ROM drive may sleep if the Mac has been idle for quite some time. As a result, it might take a bit longer for them to wake when accessed by the system.
There are workarounds, however, such as setting the hard disk sleep to “Never” under Energy Saver in System Preferences, or removing a disk you don’t use from the CD-ROM.
You can also change the standby mode settings using Terminal commands. But first, you’ll need to check the default delay for standby mode by pasting the following command into the Terminal window:
pmset -g |grep standbydelay
The result should look something like this, but the number might be different:
That’s the time in seconds. When divided by 60, you get 180 minutes, which means it will be three hours before this Mac goes into standby mode.
That can be changed to a time that better suits your needs. You can, for example, set this time to two hours (7200 seconds) or 12 hours (43200 seconds); enter the power management setting command to change this setting, which will look like this (the number changing to your preference):
sudo pmset -a standbydelay 7200
It's important to test this setting and how it affects your Mac's battery life (if applicable). You can always revert to the original setting using the above command, just change the number back to 10800 (or the original number you had).