Amphetamine not working on Mac: what to check

When Amphetamine is not working on a Mac, the problem is almost always one of four things: the session is running but macOS is not honoring it, the icon is hidden so it only looks like the app quit, closed-display mode broke after the power cable was plugged in or pulled, or a Trigger cannot see the app or device it is waiting for. Each one has a different fix, and each one can be confirmed in under a minute before anything gets reinstalled.

This guide is about Amphetamine, the free keep-awake utility for macOS by William Gustafson, not the medication. Everything below was checked on October 18, 2026 against the Amphetamine listing on the Mac App Store, the developer's own support pages on GitHub, and the Apple Mac User Guide. Version numbers and setting names are quoted as they appear there.

Start by asking macOS what is holding the Mac awake

Amphetamine does not keep a Mac awake by magic. It asks macOS for a "power assertion", the same mechanism any app uses when it needs the system to stay up. macOS will tell you exactly which assertions are active and which process owns each one. Open Terminal and run:

pmset -g assertions

The output has two parts. The top lists assertion types with a 1 or a 0, such as PreventUserIdleSystemSleep and PreventUserIdleDisplaySleep. The bottom, under "Listed by owning process", names each process and how long it has held its assertion.

Read it this way:

• Amphetamine is listed with PreventUserIdleSystemSleep. The session is working. If the Mac still sleeps, something outside the app is forcing it, such as a closed lid without the conditions closed-display mode needs, or a low battery that ended the session.
• Amphetamine is not listed at all. The session is not running, whatever the menu says. Move on to the Trigger and login sections below.
• Only the display assertion is missing. The Mac stays awake but the screen goes dark. This is a session option, not a fault. Amphetamine lets each session allow or prevent display sleep separately.

As a control test, run the built-in tool for five minutes:

caffeinate -i -t 300

The caffeinate manual page on the Mac says -i prevents idle system sleep and -t sets a timeout in seconds. If the Mac stays awake with caffeinate but not with Amphetamine, the problem is in Amphetamine's session or Triggers. If it sleeps even with caffeinate, the cause is at the system level and reinstalling Amphetamine will not change anything. One detail from the same manual page matters for laptops: the -s option, which prevents system sleep entirely, "is valid only when system is running on AC power".

The icon disappeared from the menu bar

A common report is "Amphetamine stopped working" when the app is in fact running fine but its icon is no longer visible. There are three places to check, in this order.

The notch. On MacBook models with a camera housing at the top of the screen, there is less room for menu bar icons. Bjango, the developer of iStat Menus, explains the behavior in its help page on menu bar items not showing: any items that cannot fit on the right side of the notch are hidden by macOS, and status items never appear on the left side of the notch. Amphetamine keeps running, but its pill icon is pushed out of view. Quit two or three other menu bar apps temporarily. If the Amphetamine icon reappears, the app was never broken.

System Settings on macOS Tahoe 26 and later. Apple added a list of third-party menu bar items to System Settings. According to Apple's guide to changing Menu Bar settings, open the Apple menu, choose System Settings, then click Menu Bar in the sidebar. The section titled "Allow in the Menu Bar" lists apps that "provide menu bar items for extra functionality". If Amphetamine is switched off there, its icon will not appear, even though sessions and Triggers still run.

Amphetamine's own icon setting. Amphetamine lets users replace its menu bar icon with their own image. A custom icon that is blank, very small, or the same color as the menu bar can look like no icon at all. Check the appearance options in Amphetamine's settings and switch back to a default icon to rule this out.

Closed-display mode stops working on Apple silicon

The most specific and most frequently reported failure is with closed-display mode: the MacBook lid is shut, an external display is connected, and the Mac sleeps anyway, or behaves strangely after the power adapter is connected or disconnected.

The developer documents this directly. The release notes for Amphetamine 5.3 on the App Store explain that a Closed-Display Mode script was introduced "to address an issue on Apple Silicon Macs where connecting or disconnecting your Mac laptop from an external power source could cause unexpected session behavior." Running that script first required Touch ID or an administrator password. In 5.3.1, a way to run it without authentication was added under the name Power Protect.

Three facts about Power Protect explain most of the confusion around it:

• It is not included in Amphetamine. It is a separate download from the Power Protect page.
• It is only needed, and only available, on Apple silicon Mac laptops.
• The installer asks for Touch ID or an administrator password once. After that, closed-display sessions no longer ask.

The Power Protect page lists the two files the installer creates: a script at ~/Library/Application Scripts/com.if.Amphetamine/powerProtect.scpt and a configuration file at /private/etc/sudoers.d/amphetamine_powerProtect. If closed-display mode is misbehaving, check whether both files exist. If they do, the page gives one more instruction that is easy to miss: if a Closed-Display Mode session is already running when Power Protect is installed, end it and start a new session. The fix does not apply to a session that started before installation.

The current App Store version at the time of checking is 5.3.2, released November 10, 2023. If the installed version is older than 5.3.1, update from the App Store before trying anything else in this section.

Triggers and app-based sessions do not fire

Triggers start a session automatically when a condition is met. The App Store listing names the available conditions, including while an external display is connected, while a USB or Bluetooth device is connected, while a specific app is running, while the battery is charging or above a threshold, while the Mac is on a specific Wi-Fi network, and when the Mac has been idle for a set time.

When a Trigger never fires, the cause is often a limit of the Mac App Store sandbox rather than a bug. The developer explains this on the Amphetamine Enhancer page. Amphetamine is a sandboxed app, as every Mac App Store app must be, and "getting a list of every app and process running on your Mac is something a sandboxed app can't do." A Trigger set to watch a background process, a command line tool, or a helper app may therefore never see it.

Amphetamine Enhancer is the developer's separate helper for this. According to its page, it requires Amphetamine 5.0 or later and adds two abilities: a fail-safe for closed-display mode, and the ability for Triggers and app-based sessions to use all running processes. It is open source under the MIT license, distributed outside the App Store, and notarized by Apple.

Before installing anything, though, simplify the Trigger:

• Remove every condition except one, then test that single condition.
• If the condition names an app, make sure it is the app itself and not a helper process with a similar name.
• If the condition is a Wi-Fi network or IP address, confirm the Mac is actually using that network at the moment of the test.

If a single, simple condition fires and the combined Trigger does not, the problem is the combination, not the app.

The session ends early or never starts at login

Two settings outside Amphetamine can end sessions or stop the app from starting at all.

Battery. Amphetamine can end a session automatically when the battery is low. This is listed as a feature on the App Store page, and it is easy to forget it was turned on. If sessions end at a consistent battery level, check that option in Amphetamine's settings first. Separately, on a Mac laptop, Apple's Battery settings include Low Power Mode and an Options section with "Prevent automatic sleeping on power adapter when the display is off". These system options control what the Mac does when no keep-awake session is active, so a Mac that sleeps right after a session ends can look like a failed session when it is simply following these settings.

Login. If Amphetamine is expected to start with the Mac and does not, open System Settings, click General, then Login Items & Extensions. Apple's guide to opening items automatically when you log in describes this list and the option to allow apps to run in the background. If Amphetamine was removed from the list, or background running was turned off for it, it will not start on its own after a restart. After a macOS update, switching the entry off and back on is a reasonable first step.

Rosetta. The 5.3 release notes also added a warning when Amphetamine is running using Rosetta. On an Apple silicon Mac, Amphetamine should run natively. If the warning appears, select Amphetamine in the Applications folder, choose Get Info, and turn off "Open using Rosetta" if it is checked.

When to reinstall, and when to use something else

Reinstalling is the last step, not the first. It makes sense only if pmset -g assertions never lists Amphetamine during a manual session, the icon is confirmed to be allowed and visible, and the app is on the current version. In that case, quit Amphetamine, delete it from the Applications folder, restart the Mac, and install it again from the App Store.

If the goal is a short, one-off keep-awake period, the built-in caffeinate command does the job without any app. caffeinate -d keeps the display awake as well, and caffeinate -i -t 3600 keeps the system awake for one hour. Amphetamine is the better fit when sessions need Triggers, schedules, or closed-display mode, all of which the command line tool does not provide.

Need	Amphetamine	caffeinate (built in)
Price	Free, no in-app purchases (per App Store listing)	Included with macOS
Timed session	Yes	Yes, with -t
Keep display awake	Optional per session	Yes, with -d
Automatic Triggers	Yes	No
Closed-display mode helper	Yes, with Power Protect on Apple silicon laptops	No
Menu bar control	Yes	No

What to change first

Run pmset -g assertions during a session and look for Amphetamine in the list. If it is there, the app works and the cause is the lid, the battery, or Power Protect. If it is missing, check Login Items and the Trigger conditions. If the problem is only that the icon keeps vanishing behind the notch, a menu bar manager such as Koffret keeps keep-awake controls reachable without crowding the bar, and its FAQ covers the permissions it needs.