The Energy Saver preferences pane controls how your Mac responds to inactivity. You can use the Energy Saver preferences pane to put your Mac to sleep, turn off your display, and spin down your hard drives, all to save energy. You can also use the Energy Saver preferences pane to manage your UPS (Uninterruptible Power Supply).

Understanding What “Sleep” Means in Macs

Before making any adjustments to the Energy Saver preferences pane, it’s a good idea to understand just what putting your Mac to sleep means.

Sleep: All Macs

• Your Mac’s processor goes into low-power mode, significantly reducing energy consumption.
• The Mac’s video output is turned off. Any connected display should either enter its own idle state (manufacturer dependent) or at the very least, blank the screen.
• Internal hard drives will spin down. Note: Not all third-party drives support a spin down or sleep state.

Sleep: Mac Portables

• The expansion card slot powers off. Any device that is plugged into the expansion card slot will be disabled.
• If Energy Saver optional settings allow for it, the built-in modem will turn off.
• If Energy Saver optional settings allow for it, the built-in Ethernet port is turned off.
• If Energy Saver optional settings allow for it, built-in AirPort cards are turned off.
• Optical media drive is turned off.
• Audio in and out is disabled.
• Keyboard illumination, if present, is disabled.
• USB ports are powered down, although they will respond to specific keystrokes on an external keyboard.
• The process of configuring the Energy Saver preferences pane is the same on all Macs.

Launch the Energy Saver Preferences Pane

• Click the ‘System Preferences’ icon in the Dock or select ‘System Preferences’ from the Apple menu.
• Click the ‘Energy Saver’ icon in the Hardware section of the System Preferences window.

Setting Computer Sleep Time

The Energy Saver preferences pane contains settings that can be applied to the AC power adapter, battery, and UPS, if present. Each item can have its own unique settings, which lets you tailor your Mac’s energy use and performance based on how your Mac is being powered.

Setting Computer Sleep Time

• Use the ‘Settings for’ dropdown menu to select the power source (Power Adapter, Battery, UPS) to use with the Energy Saver settings. (If you only have one power source, you won’t have a dropdown menu.) This example is for the Power Adapter settings.
• Depending on the version of OS X you are using, you may have an Optimization dropdown menu that contains four options: Better Energy Savings, Normal, Better Performance, and Custom. The first three options are preconfigured settings; the Custom option allows you to manually make changes. If the dropdown menu is present, select ‘Custom.’
• Select the ‘Sleep’ Tab.
• Adjust the ‘Put the computer to sleep when it is inactive for’ slider to the desired time. You can choose from one minute to three hours, as well as ‘Never.’ The proper setting is really up to you, and is highly influenced by the type of routine work you do at your computer. Setting it to ‘Low’ will cause your Mac to enter sleep often, which can mean you’ll have to wait until your Mac wakes up before you can continue working. Setting it to ‘High’ negates the energy savings possible when sleeping. You should only use the ‘Never’ option if you dedicate your Mac to a specific function that requires it to always be active, such as use as a server or a shared resource in a distributed computing environment. I have my Mac set to go to sleep after 20 minutes of inactivity.

Setting Display Sleep Time

Your computer’s display can be a significant source of energy use, as well as a battery drain for portable Macs. You can use the Energy Saver preferences pane to control when your display is put into sleep mode.

Setting Display Sleep Time

• Adjust the ‘Put the display(s) to sleep when the computer is inactive for’ slider to the desired time. This slider has some interaction with two other energy-saving functions. First, the slider cannot be set for a time longer than the ‘Put the computer to sleep’ slider because when the computer goes to sleep, it will also put the display to sleep. The second interaction is with your screen saver if activated. If the screen saver start time is longer than the display sleep time, the screensaver will never start. You can still set the display to go to sleep before the screen saver kicks in; you will just see a little warning about the issue in the Energy Saver preferences panel. I set mine to 10 minutes.
• If you are using a screen saver, you may wish to adjust or even turn off the screen saver function. The Energy Saver preferences pane will display a ‘Screen Saver’ button whenever your display is set to go to sleep before your screen saver can be activated.
• To make changes to your Screen Saver settings, click the ‘Screen Saver’ button, then take a look at “Screen Saver: Using the Desktop & Screen Saver Preference Pane” for instructions on how to configure your screen saver.

Putting Your Hard Drives to Sleep

The Energy Saver preferences pane allows you to sleep or spin down your hard drives whenever possible. Hard drive sleep does not affect display sleep. That is, your drive spinning down or waking from hard drive sleep will not affect display sleep, either in waking or in registering as an activity to keep the display awake.

Putting your hard drive to sleep can save considerable energy, especially if you have a Mac with lots of hard drives installed. The downside is that the hard drives can be spun down by the Energy Saver settings long before your Mac goes to sleep. This can cause an annoying wait while the hard drives spin back up. A good example is writing a long document in a word processor. While you’re writing the document there is no hard drive activity, so your Mac will spin all hard drives down. When you go to save your document, your Mac will seem to freeze, because the hard drives must spin back up before the Save dialog box can open. It’s annoying, but on the other hand, you saved yourself some energy use. It’s up to you to decide what the tradeoff should be. I set my hard drives to go to sleep, even though I am sometimes annoyed by the wait.

Set Your Hard Drives to Sleep

If you want to set your hard drives to sleep, place a check mark next to ‘Put the hard disk(s) to sleep when possible’ option.

Energy Saver Options

The Energy Saver preferences pane offers additional options for energy management on your Mac.

Energy Saver Options

• Select the ‘Options’ tab.
• There are two ‘wake from sleep’ options, depending on the model of your Mac and how it is configured. The first, ‘Wake for Ethernet network administrator access,’ is present on most late-model Macs. The second, ‘Wake when the modem detects a ring,’ is present only on Macs configured with a modem. These two options allow your Mac to wake up for specific activity on each port.
• Make your selections by placing or removing the check marks from these items.
• Desktop Macs have the option to ‘Allow power button to sleep the computer.’ If this option is selected, a single push of the power button will put your Mac to sleep, while an extended hold of the power button will turn off your Mac.
  Make your selections by placing or removing the check marks from these items.
• Portable Macs have the option to ‘Automatically reduce the brightness of the display before display sleep.’ This can save energy as well as give you a visual indication that sleep is about to occur.

Make your selections by placing or removing the check marks from these items.

• The ‘Restart automatically after a power failure’ option is present on all Macs. This option is handy for those who use their Mac as a server. For general use, I don’t recommend enabling this setting because power failures usually come in groups. A power outage may be followed by a power restore, followed by another power outage. I prefer to wait until the power seems to be steady before turning our desktop Macs back on.

Make your selections by placing or removing the check marks from these items.

There are other options that may be present, depending on Mac model or peripherals attached. Additional options are usually pretty self-explanatory.

Energy Saver: Energy Saver Settings for UPS

If you have a UPS (Uninterruptible Power Supply) connected to your Mac, you may have additional settings that control how the UPS will manage power during an outage. In order for the UPS options to be present, your Mac must be plugged directly into a UPS, and the UPS must be connected to your Mac via a USB port.

Settings for UPS

1. From the ‘Settings for’ dropdown menu, select ‘UPS.’
2. Click the ‘UPS’ tab.
3. There are three options for controlling when your Mac will shut down when on UPS power. In all cases, this is a controlled shutdown, similar to selecting ‘Shut Down’ from the Apple menu.

Shutdown Options

• The ‘Shut down the computer when it has been on UPS power for’ option lets you specify a time frame from one minute to the maximum expected run time of your UPS when on battery power before your Mac will automatically shut down.
• The ‘Shut down the computer when time left on the UPS power is’ option lets you select a time frame from one minute to the maximum expected run time of your UPS when on battery power before your Mac will automatically shut down.
• The ‘Shut down the computer when the UPS power level drops to’ option is based on a percentage of remaining power. You can select from one to 100 percent. When the UPS reaches that percentage of remaining power, your Mac will shut down.

You can select more than one option from the list. Your Mac will shut down whenever any of the selected option’s conditions are met.

1. Place a checkmark next to the UPS option(s) you wish to use.
2. Adjust the slider for each item you checked to specify the time frame or percentage values.

Energy Saver: Scheduling Startup and Sleep Times

You can use the Energy Saver preferences pane to schedule times for your Mac to start up or wake from sleep, as well as a time for your Mac to go to sleep.

Setting a startup time can be useful when you have a routine schedule you keep, such as starting to work with your Mac every weekday morning at 8 am. By setting a schedule, your Mac will be awake and ready to go when you are.

Setting a startup schedule is also a good idea if you have a group of automated tasks that run every time you start up. For instance, you may back up your Mac each time you turn your Mac on. Since these types of tasks take a little while to complete, having your Mac start up automatically before you get to work on your Mac ensures these routine tasks are finished and your Mac is ready to work.

Scheduling Startup and Sleep Times

• In the Energy Saver preferences pane window, click the ‘Schedule’ button.
• The sheet that drops down will contain two options: ‘Setting a Startup or Wake Time’ and ‘Setting a Sleep, Restart, or Shutdown time.’

Set a Startup or Wake Time

• Place a checkmark in the ‘Startup or Wake’ box.
• Use the dropdown menu to select a specific day, weekdays, weekends, or every day.
• Enter the time of day to wake or startup.
• Click ‘OK’ when you’re done.

Set a Sleep, Restart, or Shutdown Time

• Place a checkmark in the box next to the ‘Sleep, Restart, or Shutdown’ menu.
• Use the dropdown menu to select whether you wish to sleep, restart, or shut down your Mac.
• Use the dropdown menu to select a specific day, weekdays, weekends, or every day.
• Enter the time of day for the event to occur.
• Click ‘OK’ when you’re done.