Tech Tip: Should You Shut Down Your Mac or Let It Sleep?

One question that new Mac users often ask is whether they should shut down their Macs at the end of the day or just let them sleep. The quick answer is that sleep is better for your Mac, and in today’s Tech Tip we’ll show you why it’s better to just let your Mac go to sleep than shut it down each day.

Shutting Down Your Mac Keeps It From Running Maintenance Tasks
The main reason for letting your Mac sleep instead of shutting it down is that your Mac can’t perform maintenance tasks during the night if you shut it down. macOS does a lot every night while your Mac isn’t being used and it is “sleeping”. Apple actually has a term for this sleep mode — “Power Nap”. 

So what does it do during a Power Nap? A lot:

  • Mail receives new messages.
  • Contacts keep up to date with changes made on other devices.
  • Calendar receives new invitations and calendar updates.
  • Reminders keep up to date with changes made on other devices.
  • Notes keep up to date with changes made on other devices.
  • Documents stored in iCloud keep up to date with changes made on other devices.
  • Photo Stream keeps up to date with changes made on other devices.
  • Find My Mac updates the location of the Mac, so you can find it while it’s asleep.
  • VPN on demand continues working so that your corporate email updates securely. (Power Nap supports VPN connections that use a certificate to authenticate, not VPN connections that require entering a password.)
  • Mobile Device Management can remotely lock and wipe your Mac.

If your Mac is plugged into AC and taking a Power Nap, it will also do the following:

  • Software updates download.
  • Mac App Store items (including software updates), download in the background.
  • Time Machine performs backups.
  • Spotlight performs indexing.
  • Help Center content updates.
  • Wireless base stations can wake your Mac using Wake on Wireless.

While your Mac appears to be sleeping, it’s actually doing a lot! The good part of all of this is that when you get back behind the keyboard and you’re ready to start working, your Mac wakes up quickly from sleep and is ready to get to work. There’s no need for it to go through the startup procedure, and it has already done all of the maintenance jobs it needs to do, so it’s ready to roll. 

Mac users new and old often say that their Macs are running slowly, and when asked they usually say that they’re shutting down the Mac every night. It’s not surprising that the machines seem slow, as the Mac needs to run through all of the maintenance tasks it should have been doing while sleeping.

What Macs Support Power Nap?
Most Macs built since the early 2010s support Power Nap:

  • MacBook (Early 2015 and later)
  • MacBook Air (Late 2010 and later – requires OS X Mountain Lion v10.8.2 and later)
  • MacBook Pro (all models with Retina display)
  • Mac mini (Late 2012 and later)
  • iMac (Late 2012 and later)
  • Mac Pro (Late 2013)

How Do I Enable Power Nap?
Owners of any of the Macs listed above should have Power Nap enabled by default. To make the Mac “go to sleep”, one can select Apple menu – Sleep from the menu bar, close the screen on a Mac laptop or move the cursor into what’s called a Hot Corner. 

Hot Corners are defined in the Desktop & Screen Saver system preference. In the lower right corner of the preference pane is a button for Hot Corners. Click it and a diagram showing the four corners of the primary display appears. Each corner can have something assigned to it — in the screenshot below, Put Display to Sleep has been selected for the lower right corner of the screen. Using the mouse or trackpad to place the cursor in the Hot Corner puts the device to sleep.

(Selecting a Hot Corner for putting a Mac to sleep)

(Selecting a Hot Corner for putting a Mac to sleep)

To make sure that your Mac has Power Nap enabled, go to System Preferences > Energy Saver. You’ll see the following preference pane, and just need to ensure that Enable Power Nap is checked. 

(Power Nap is enabled on the Energy Saver System Preference pane)

(Power Nap is enabled on the Energy Saver System Preference pane)

Am I Wasting Energy or Contributing to Climate Change By Not Shutting Down My Mac?
If you’re energy-conscious, you might be wondering if you’re wasting power by putting your Mac in Power Nap mode instead of turning it off. Well, it turns out that your Mac uses energy even when it is plugged in and turned off!

You can find out exactly how much power your Mac uses by visiting the Apple Product Environmental Report page. Near the bottom of this page, you can find environmental reports for every product Apple has made since 2009, and that information includes just how much power your device consumes.

For example, I use a 27-inch iMac with a Retina 5K Display as my primary computer. When it is idle (that is, not actively performing any tasks) and the display is turned on, it uses 69.1W of power. Put that iMac to sleep, and it uses only 1.22 W of power. Turning the Mac all the way off, but keeping it plugged in, power use goes down to 0.24W. 

The difference in power consumption between sleeping the Mac and turning it off is only .98 W, meaning that over a year, I’m using an additional 5.7 kWh (kilowatt hours) of power (assuming I actively use the Mac eight hours per day). At the current average residential electricity rate in my part of the country (12.04 cents per kWh), turning off that Mac each night would only save me about $0.69 per year. 

That 5.7 kWh also adds only about 5.68 lbs of CO2 to the atmosphere per year. Considering that burning a gallon of gasoline creates 19.6 pounds of CO2 and the average car currently gets about 22 miles per gallon, just driving .26 miles would create an equal amount of CO2 as is generated to power a sleeping iMac instead of turning it off.


LEAVE A COMMENT


  • Does this advice apply to Macs without Power Nap in System Prefs?




  • With my 2008 Mac Pro and OS 10.11.6, I was finding that my available space was decreasing 5GB to 10GB if I didn’t restart periodically. Some operations were slowed. With the 2018 Mac mini, I have found that after a week or more, the loss of storage space was down maybe 3GB to 5GB. An improvement with Mojave over El Capitan.




  • I’ve found it more beneficial, both for me and my iMac 27″ 5K to simply shut down for the night. Why? Because about 30% of the time in plain Sleep mode, it crashes and restarts during the night. The rest of the night, it usually wakes up about every 70 minutes or so for about 45 seconds, then goes back to sleep, which activates all my external drives and makes too much noise, interrupting my own Sleep. I have NO need for the “Power Nap” and would say that most people really don’t need that feature. Just chill and power off. Ah, quiet and calm.




  • I Never heard of Power Nap before. I was happy to find out that both my computers are using Power Nap. Your article is clear and thorough. Thank You very much .




  • thank you for all of your info.




  • There’s another good reason to put your Mac to sleep instead of switching it off. The physical stress on various components due to thermal cycling between active and off states is reduced if the computer never really gets as cold as it does when it’s switched off. So, sleep adds life to the computer.




  • I cannot understand how anybody can possibly leave their (modern) Mac running for months… Unless you are either not using it or you are running an older OS. Ever since I switched to 10.13 (when it was released) the kernel crashes hard at least twice a month… Sometimes within just a few days of the last crash.




  • And a million sleeping macs use 5,700,000 kWh per year




  • i always shut mine down at days end, i don’t mind waiting 2 extra seconds for email to load, or for the
    small amount of time needed for updates.




  • Great Article. I am “upgrading” from a 2009.5 MBP laptop to a 2019 21.5 iMac.

    Glad to get all of these tips.
    Have a great day from Sun City West, AZ
    73
    DavidCee




  • Great article! It answers a lot of important questions. Mac should include a manual that answers questions like these with every computer they sell.




  • Thanks for posting this. Nevertheless I will continue to power my various portables and iMacs down rather than let them sleep, for the following reasons:
    (1) at this point in time, any reduction in energy use should be encouraged and applauded. As an example, think about the additional CO2 if a million users follow your advice, that’s at least another 5,000,000 pounds of CO2 for literally no good reason. I urge to to avoid the idea that energy use is “trivial”. Nothing is trivial with 7.5+ billion humans on the planet.
    (2) It’s been my experience that many macs have problems waking from sleep. It’s far safer to shut it down than to have it freeze and refuse to wake.
    (3) There’s no reason users can’t get in the habit of doing their own maintenance, as programs like Onyx are quite easy to use.




  • I purchased my 27″iMac in 2011. I checked, I do not have the Power Nap. I have always let my Mac sleep. I only shut down a couple times a week for a re-start. What suggestions do you have for me?




  • This is true and has been my practice for years. However, it is a good idea to shut down and then restart your Mac about every 3 weeks to clean out memory cache(s) and reset other little things.




    • In my case, I’m using enough concurrent memory-intensive apps at times that a utility like Clean My Mac comes in handy for freeing up RAM during the day and on demand. I always leave mine in sleep mode at night so a backup can run without impacting daytime usage.




  • What about attached drives during sleep. What happens when a firewire dirive is “unplugged” while MacBook Pro asleep. Is it at risk of corrupted data?
    Put computer to sleep 9PM. at 6AM unplug attached drives and external monitor to take computer to work.
    Advice please




  • My history suggests that “Sleep Mode” ejects external drives (improperly). Does the Power Nap take this into consideration?




    • What Mac are you using?
      With my Mac Pro and with the external drives connected through the eSata, I was having that problem – it just could not maintain the connection.

      With my Mac mini (2018), I had the same problem when the external drives were plugged into a USB 3.0 hub. I would wake the Mac mini to find multiple notifications that my disks had been improperly ejected. Evidently, the 10-port hub does not maintain a connection 100% of the time. The hub also kept dropping the Logitech mouse when the receiver was plugged in there. Now it is in the USB port of my wired keyboard. No more mouse problems.
      The external drives are now connected through the USB hub (Anker) plugged into one of the Thunderbolt ports of the Mac mini.




  • If the Mac is sleeping at night, it’s not likely producing any extra CO2 usage. Power plants are running all night, whether you use that minuscule amount or not.




  • Thanks for this post, Steve.

    I’m interested in how you think connected hard drives affect this strategy.

    What’s always kept me from using sleep (vs shutting down) are my connected drives, which keep running even if my iMac is power napping. So while my CPU is only using a sliver more energy than vs shut down, my drives are still using power, tilting the balance well in favor of shutting down. Plus, since drives only have so many hours of use, logging 8 or more additional hours overnight.

    Still, would you still Power Nap vs shut down in my case?




  • My 2018 27″ Retina iMac frequently shuts itself down with a kernel panic (overnight) when I stay logged in but sleeping. I did not have “Power Nap” enabled, so I will try that.




  • The only problem I’m seeing now is with recent updates, my iMac is very slow to wake from sleep.




  • There’s an error in your last calculation.

    Assuming your estimate of 5.68 lbs of CO2/5.7 kWh of electricity is correct, then 5.7 kWh is the equivalent of driving about 6.4 miles in a car getting 22 mpg.




  • My problem is that sometimes, when I put my MAC to sleep, it doesn’t wake up. The screen is blank when I open up the MAC. It is not due to a lack of battery power either. Otherwise, the keys may light up, or the screen should show up, but even after at least 5 minutes, I can’t get the keyboard to respond.




    • “My problem is that sometimes, when I put my MAC to sleep, it doesn’t wake up”.

      What Mac model and macOS version? It could be a defective GPU.




      • I’ve got a similar problem with my late 2015 iMac running 10.14.3. If I manually put it to sleep it sometimes fails to wake up in the morning via BT keyboard or trackpad.

        After reading this I did turn on Power Nap. We shall see if that helps or not.




        • Pavel, Jazz1 – I had the same issue (screen not waking up) with my last iMac. After a while with Apple support a reset of SMC and PRAM (or NVRAM… can’t remember) fixed this.




        • My Mac mini (2018) has OS 10.14.3. It replaced a 2008 Mac Pro because Apple didn’t produce the new Mac Pro and I didn’t want to buy a ‘new’ one with 5-year-old electronics.
          I thought it was not waking from sleep. I usually tap the mouse button to wake it. If that does not wake it in 5-7 seconds, I tap the return key (wired keyboard). If that does not work, I tap the key I have programmed to take a screen shot. Then I hear the chime that tells me it took a screen shot, so I know it is the display not waking. I unplug the USB-C plug behind the Mac mini and re-insert it. The display is ON.
          Something is preventing the Mac mini Thunderbolt port from sending the signal to the display (23″ Apple Cinema Display). It has occurred 4 times in the 3 months I have had this Mac mini.

          If you have an iMac, then you probably don’t have a connection problem, but you never know.




        • I have the same problem. I had ask it to never sleep. Says it shortens life of monitor ? My Mac mini shuts down when I let it go to sleep. Need to turn it on with the power switch ?




    • There’s been a long-standing “complaint” out there about the screen saver locking up. I’ve got one of the early Mac Pro and suffered from this – sometimes the screen saver would lock after a couple of hours, necessitating a reboot – very irritating. I’ve taken to logging out, leaving myself at the login screen but with box still running.




  • Sure; Recently read article sayings OWC had a turnkey program to upgrade “vintage” iMac to “better than new…”. Can my late 2009 (10.1) 3.06, 21.5in w/8gb ram, 500,gb SSD be any further upgraded? If sox cost?
    Appreciate any info.
    Lloyd Stevenson




  • Thank you for the facts on this issue. Of course the other question is how much, if any, wear and tear shutting down and starting up a Mac every day causes compared to sleeping it every night.




  • I don’t find Power Nap option using Apple Menu, system preferences, Energy Saver and using Mojave 10.14.3 . Where did it go?




    • Do you see all the other options?
      •_Prevent computer from sleeping automatically …
      •_Put hard disks to sleep when possible
      •_Wake for network access
      •_Start up automatically after power failure

      And does it have the statement “While sleeping, your Mac can back up using Time Machine and …”?

      If the Enable Power Nap is the only item missing, maybe you can try the Restore Defaults.




  • Or leave it up and running all the time so you can contribute to World Community Grid and help solve some of the world’s problems.
    https://www.worldcommunitygrid.org/




    • My desktop Mac has racked up 1,550,000 BOINC credits helping out a variety of compute-intensive projects over the years — while I’m asleep or away from my desktop. Does this create more wear and tear on my desktop than simple being asleep?




      • I configure my mac to let the display sleep but never the processor. Drives will usually spin down on their own due to lack of activity.

        I’ve been running WCG since 2004, before it moved to BOINC. I’ve used Win pcs and now Mac Minis. Almost always running 24×7. In all that time I haven’t had any hardware problems caused by such work (that I know of). I am concerned about running a continuous heavy resource load on macs so I usually limit the cpu load to +/- 20% to prevent over heating.

        If anyone really wants to stress test a computer try running GIMPS aka PRIME95. :-)