MacBook Pro will not go to sleep.

No. This is always due to a process keeping the system awake, but determining which is the challenge.

• A first simple step is to create a new, temporary user account. Log out of yours and log into the temporary one. Determine if it sleeps then. If it does then you have a login item that is preventing sleep. System Preferences > Users & Groups > Login Items.
• Whenever you suspect a problem related to power, including sleep, an SMC reset is also recommended.
• Active Spotlight indexing will prevent sleep. Wait for it to complete. That may take several hours following an OS X upgrade.
• Check your Sharing preferences for anything that could permit an active network connection.
• Energy Saver "Wake for network access" can prevent sleep, but unchecking it will prevent the ability to remotely access a sleeping Mac over a network.
• A normally functioning Mac will sleep according to Energy Saver, but will wake periodically for network access, after which it will return to sleep according to the settings in Energy Saver.
• Check Energy Saver > Power Nap. Whatever its setting happens to be, change it. Power Nap itself does not prevent sleep, but a corrupted Power Nap setting might. Changing its setting might correct it.
• Unfinished print jobs will prevent sleep. If a print job is queued, but if the printer is off or the connection to it is lost, the Mac will stay awake forever waiting for the printer to return.
• Safari pages that periodically refresh themselves are very common. This will prevent sleep.
• Frequently checking for new mail may prevent sleep. Change Mail's preferences to check for new mail less frequently.
• iTunes and iPhoto sharing will prevent sleep.
• Active Bluetooth devices will prevent sleep.
• Active USB or Thunderbolt devices will prevent sleep. Disconnect them to help isolate the cause.
• Using Time Machine over a network may prevent sleep. Time Machine using a Time Capsule will not.
• There are plenty of third party utilities designed to prevent sleep. One may not have been completely uninstalled.
• Quit the process with the name powerd in Activity Monitor. It will re-launch on its own.
• Any number of "anti-virus" utilities can prevent sleep, along with other miseries. Get rid of them.

Read Mac OS X: Why your Mac might not sleep or stay in sleep mode

It may be instructive to identify the actual process that is preventing sleep. The following instructions can be used with any OS X version.

• Open Terminal and Activity Monitor. Both are in your Utilities folder. Leave them open.
• Open System Preferences > Energy Saver, and set the Mac to sleep after the shortest possible idle time (one minute)
• Wait a minute, during which you touch nothing
• When it becomes obvious the Mac will not sleep, type the following in the Terminal window, followed by the Return key:

pmset -g

Look for the line resembling the following:

sleep 1 (sleep prevented by 360)

• Note the process ID (360 in the above example). Mavericks will indicate the process name directly.
• In Activity Monitor, select Window > Activity Monitor, and select the CPU tab. Click on the column with the heading "PID" to sort processes by their process ID. Find the Process Name corresponding to the PID above.

That will be the process that prevented sleep.

There are probably some setting that you have to change in the system preferences. Nothing major.

To help determine the possible causes of this behaviour read the following. None of what follows is intended to fix anything, but it will provide the additional information required to advance troubleshooting:

Boot OS X Recovery by holding ⌘ and r (two fingers) while you start your Mac. At the Mac OS X Utilities screen, select Disk Utility. Select your startup volume (usually named "Macintosh HD") and click the Repair Disk button. Describe any errors it reports in red.

When it finishes restart your Mac and test again for operation. If it's still not behaving as you expect it should, please post the results of EtreCheck in accordance with the following instructions:

Apple Support Communities contributor etresoft wrote a very useful app to quickly gather certain system information that may help point to a cause of this problem. Go to his website, download and run EtreCheck:

http://www.etresoft.com/etrecheck

Etrecheck will be in your Downloads folder. Open it from there. You may see the following dialog box:

Click Open - etresoft contributes to this forum frequently and can be considered a trustworthy developer.

It will take a moment to run as it collects its data.

Copy and paste its output in a reply.

Do not be concerned about anything that says "Problem" or “failed” or anything else that may appear in red.

EtreCheck was designed to remove any personal information (such as your computer's name and serial numbers) but if you see anything that looks like an email address or any other personal information that should not be divulged to others, please delete or obscure that information when you post the reply.

When you are finished with EtreCheck, quit the program. It occupies very little space, and you can keep it or drag it to the Trash as you wish.

After completing the above please determine if the problems also occur in "Safe Mode":

• Safe Mode or "Safe Boot" is a troubleshooting mode that bypasses all third party system extensions and loads only required system components. Read about it: Starting up in Safe Mode
• You must disable FileVault before you can start your Mac in Safe Mode.
• Starting your Mac in Safe Mode will take longer than usual, graphics will not render smoothly, audio is disabled on some Macs, and some programs (iTunes for example) may not work at all.
• Merely starting your Mac in Safe Mode is not intended to resolve the problem, it's to observe its performance without certain additional components.
• To end Safe Mode restart your Mac normally. Shutdown will take longer as well.

Uninstall all Trend Micro "security" software according to its instructions. Ensure all its components are completely eradicated from your Mac, and evaluate its performance.

If you performed theSMC reset that's all you can do. It won't harm anything to do it again.

Before Resetting the SMC

Try each of the following steps in this order before you reset the SMC. Test the issue after completing each troubleshooting step to determine if the issue still occurs.

1. Press Command + Option + Escape to force quit any application that is not responding.
2. Put your Mac to sleep by choosing the Apple () menu from the upper-left menu bar and then choosing Sleep. Wake the computer after it has gone to sleep.
3. Restart your Mac by choosing the Apple () menu from the upper-left menu bar and then choosing Restart.
4. Shut down your Mac by choosing the Apple () menu from the upper-left menu bar and then choosing Shut Down.

Resetting the SMC on Mac portables with a battery you can remove

1. Shut down the computer.
2. Disconnect the MagSafe power adapter from the computer, if it's connected.
3. Remove the battery (to remove the battery - click here: MacBook or MacBook Pro).
4. Press and hold the power button for 5 seconds.
5. Release the power button.
6. Reconnect the battery and MagSafe power adapter.
7. Press the power button to turn on the computer.

Still having problems? Replace steps 6 and 7 with the following:

1. Reconnect just the MagSafe power adapter.
2. Press the power button to turn on the computer,
3. Then reconnect the battery.

Resetting the SMC on portables with a battery you should not remove on your own

1. Shut down the computer.
2. Plug in the MagSafe power adapter to a power source, connecting it to the Mac if it's not already connected.
3. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time. The power adapter indicator light should cycle off / on once.
4. Release all the keys and the power button at the same time.
5. Press the power button to turn on the computer.

If you don't mind, please post the Terminal results of pmset - g as I wrote earlier. Copy and paste them in a reply. There are only a few lines of output. Thanks.

Same here. The Mackbook only sleeps when I quit Microsoft Word. If I leave it running, Macbook never sleeps, including the display.

There's any way to avoid Microsoft Word to do this?

Hello.

Having exactly the same problem as Pelem originally described. My Macbook Pro will go to sleep and then not wake back up, the white stand by light on the front doesn't flash intermittently and it's like it's been shut down- the only way to wake it up is to do a hard boot.
I did the Etre Check described, and it came back saying everything was fine.

Any suggestions?

Thank you.

I did the Etre Check described, and it came back saying everything was fine.

EtreCheck does not say everything is fine. You are misusing it.

Return to his website, learn what it does, and then start your own Discussion. Pelem has not replied to requests for more information, and after four months it is not reasonable to expect any further reponses.

Of course it didn't actually say 'everything is fine', I can't remember exactly what the words were. I did actually start my own discussion as I was aware that Pelem had not replied for a while. Pelem's original post was the reason why I found this particular thread discussion and forum as it's exactly the issue as I was having and thought it would possibly be helpful if anyone new came on board to help and saw what the previous discussion was saying.

Frankly, you reply has come off a bit rude, so... cheers.

I was having the same problem with my MBP not going to sleep no matter what I did. The fix for me was turning off internet sharing after diagnosing that this prevented the machine from going to sleep using John Galt's suggestion below. Thanks John! I am not sure why this was even on and maybe by default judging by the number of people with this problem. Good luck all!