How to Temporarily Prevent Your Mac from Sleeping

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Let’s say you start a big download, then go to bed. When you wake up, you realize your Mac went to sleep before finishing its job. Isn’t there some way to stop this?

You probably know you can go into your Mac’s System Preferences > Energy Saver and change how often it goes to sleep.

But occasionally, you want to keep it awake indefinitely, or for a different amount of time than what you have set in System Preferences. Instead of changing your permanent settings, you can apply some temporary settings with a free Mac app called Amphetamine. It also lets you program your Mac to stay awake under particular conditions, such as when a particular Wi-Fi network is nearby, a certain app is open, or during set hours of the day.

You can also do some of this with a simple Terminal command, Amphetamine is much more powerful, if you’re willing to install an extra app.

How to Use Amphetamine

Download, install, and launch Ampetamine like you would any other Mac app. When you do, and you’ll see a new icon in the menu bar that looks like a pill. (You can customize this icon, but we’ll get to that in a bit.)

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Click this icon and you can quickly toggle your Mac to stay awake “Indefinitely.” Alternatively, you can keep your Mac awake for a set number of minutes…

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…or a particular number of hours.

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If this isn’t enough for you, you could also keep your Mac awake while a certain program is running. Why would you want this? Perhaps you’ve set up your download manager to close once a download is completed, and you want to ensure your Mac keeps running until that is done. If you can’t imagine yourself using that feature, just stick to the timed options.

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A Powerful Set of Configuration Options

If you’re the sort of user who likes to configure everything so it’s just right, you’re going to love the settings panel offered by Amphetamine. Click the menu bar icon and head to “Preferences” to tweak to your heart’s content.

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For example, if you just want your Mac to stay awake when you click the icon, you can set that up by toggling the “Status Bar Icon Click Actions” dropdown. You can also decide whether your screen stays awake, or whether it goes to sleep, while your Mac is kept awake.

In the Battery panel, you can tell Amphetamine to stop keeping your Mac awake once your battery sinks to a set level.

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Unless you want your Mac to stay awake until the battery dies, this is a good idea.

There are a few more interesting panels here, which give you even more power:

  • The Drive Alive panel allows you to force particular hard drives to stay awake, instead of powering down, while your computer is kept awake.
  • The Hotkeys panel lets you set up universal keyboard shortcuts for starting and ending sessions.
  • The Notifications panel lets you decide whether Amphetamine will notify you of sessions beginning and ending, and what sounds the program makes.
  • The Appearance panel lets you change the icon from a pill to a coffee carafe (my preferred icon), a teapot, or even an owl.

There’s really no part of Amphetamine that the user can’t control, which makes it a power user’s dream. But users who’d prefer to ignore these settings never need to look at them: the menu bar icon is enough for the vast majority of users.

Set Up Advanced Triggers for Automatic Caffeination

There’s one panel I’ve yet to mention: Triggers. This lets you set up rules about when your Mac should stay awake.

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To get started, head to the Triggers section, then click the “+” button to create a new trigger.

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Now you can set up a series of conditions that will automatically keep your Mac awake. For example, if you don’t want your Mac to go to sleep on weekdays when you’re at home, you could set your Wi-Fi network and a particular time range. Alternatively, you could set up Amphetamine to keep your Mac awake anytime your download manager is open. You’ve got a lot of power here, so dig in. Just note that Amphetamine must be running for the triggers to activate.

Justin Pot is a staff writer for How-To Geek, and a technology enthusiast who lives in Hillsboro, Oregon. Follow him on Twitter and Facebook, if you want. You don't have to.