# Why won’t my Mac sleep? How to find what is keeping it awake

Canonical page: https://vitalsmac.com/mac-wont-sleep

By Atta Ur Rehman Shah, maker of Vitals. Published September 29, 2026.

**Short answer:** Open Terminal and run `pmset -g assertions`. Under “Listed by owning process”, each line names an app that is holding sleep off, for how long, and the reason it gave. Activity Monitor marks the same apps Yes in the Energy tab’s Preventing Sleep column. The usual causes are a video or call left open in a browser tab, a download or backup, a `caffeinate` command still running, and settings that keep the Mac awake on power. On a MacBook, the Vitals system monitor lists these apps without Terminal, on its Battery tab and in the menu bar, with the reason and how long.

## How to find what is keeping your Mac awake

1. Open Terminal and run `pmset -g | grep sleep`. If something is holding sleep off, the sleep line ends with a note such as (sleep prevented by Google Chrome, powerd).
2. Run `pmset -g assertions` for the detail. Under “Listed by owning process”, each line gives the app and its PID, how long it has held sleep off, the type of hold, and after the word named, the reason it gave, such as "Video Wake Lock".
3. Ignore powerd’s "Prevent sleep while display is on" and the UserIsActive lines. They only mean you are using the Mac, and go away when you stop.
4. Open Activity Monitor, click Energy, and look at the Preventing Sleep column. Yes marks the same apps, and you can quit one from there.
5. Quit the app, or close what it is doing: the tab playing video, the call, the download. Run `pmset -g assertions` again to check the line has gone.

A Mac that sleeps but keeps waking up is a different problem, with its own log. See "When the Mac wakes up by itself" below.

A Mac sleeps when nothing asks it not to. Apps ask by creating a power assertion: a request macOS records with the app’s name and its reason. A video player, a call, a download or a backup asks for good reason. The trouble starts when the request outlives the reason: a tab playing a muted video, a call that ended in another tab, a `caffeinate` in a terminal window you forgot. The table below matches what you see to the likely cause and where to look.

## Why a Mac stays awake

| What you notice | Likely cause | Where to check |
|---|---|---|
| The screen never turns off | An app holding the display on: a video, a call, a presentation | `pmset -g assertions`: PreventUserIdleDisplaySleep |
| The screen turns off but the Mac never sleeps | A download, a backup, a sync or a build holding the system awake | `pmset -g assertions`: PreventUserIdleSystemSleep |
| It never sleeps while plugged in | A setting that keeps it awake on power | System Settings → Battery → Options, or Energy on a desktop |
| It sleeps, then wakes on its own at night | Scheduled maintenance, the network, or a connected device | `pmset -g log`, and `pmset -g sched` |
| It stays awake after you ran a Terminal command | `caffeinate` still running | Activity Monitor: search for caffeinate |
| It stays awake while other devices use its connection | Internet Sharing | System Settings → General → Sharing |

## What the assertion types mean

Each line in `pmset -g assertions` names a type. Three of them keep the Mac awake. The rest are bookkeeping, and seeing them is normal.

- PreventUserIdleDisplaySleep, or NoDisplaySleepAssertion: keeps the screen on, and the Mac with it. Video players, video calls and presentations use it.
- PreventUserIdleSystemSleep, or NoIdleSleepAssertion: keeps the Mac awake while the screen is free to turn off. Downloads, backups, music playing and builds use it.
- PreventSystemSleep: keeps the Mac awake even with the lid closed on power. Rare; usually a system service.
- UserIsActive, BackgroundTask and ApplePushServiceTask: bookkeeping that does not hold sleep off by itself.

## When the Mac wakes up by itself

A Mac that went to sleep can still wake briefly on its own, with the screen off, to check mail, sync, back up or run maintenance. macOS calls this a dark wake. A few a night are normal. Dozens, or full wakes with the screen on, point at a device or a setting.

1. Run `pmset -g log | grep -E "Wake from|DarkWake from" | tail -20` to see the last 20 wakes. The text after “due to” names the cause: lid means you opened it, rtc/Maintenance is a scheduled maintenance wake, and names of USB, Bluetooth or network devices point at that device.
2. Run `pmset -g sched` to see wakes macOS has scheduled for later, and which part of the system asked for each.
3. If a device is waking the Mac, unplug it overnight and see whether the wakes stop.
4. If network wakes are the cause, set Wake for network access to Only on Power Adapter or Never, in System Settings → Battery → Options on a MacBook or System Settings → Energy on a desktop Mac.

## Settings that keep a Mac awake on purpose

Some settings keep a Mac awake by design. Check them before you look for a misbehaving app.

- On a MacBook, Prevent automatic sleeping on power adapter when the display is off, in System Settings → Battery → Options.
- On a desktop Mac, Prevent automatic sleeping when the display is off, in System Settings → Energy.
- Internet Sharing, in System Settings → General → Sharing, which keeps the Mac awake while other devices use its connection.
- Display sleep set to Never in System Settings → Lock Screen, which keeps the screen on and the Mac awake with it.

## caffeinate, and apps that keep a Mac awake on request

`caffeinate` is the macOS command that keeps a Mac awake for as long as it runs. Scripts and developer tools use it, and so do keep-awake menu bar apps. It shows in `pmset -g assertions` under its own name, and in Activity Monitor as caffeinate.

If you started it, press Control-C in its Terminal window. If you did not, find which app started it: in Activity Monitor, choose View → All Processes, Hierarchically and look for caffeinate under its parent. Quitting the parent stops it.

## What Vitals adds

On a MacBook, Vitals names the apps keeping it awake, in plain words, without Terminal.

- Keeping This Mac Awake, on the Battery tab: each app with the reason it gave, such as Playing video or Downloading, how long it has held sleep off, and whether it keeps the screen on
- The same list in the Battery section of the menu bar dropdown while an app is holding sleep off, so you can check before you close the lid
- A browser is one line however many tabs are playing, and a `caffeinate` left in a terminal shows as Asked to stay awake
- Free to Sleep when nothing is holding it

Good to know:

- The list is on MacBooks only. On a Mac mini, iMac, Mac Studio or Mac Pro, use `pmset -g assertions`.
- It leaves out macOS’s own processes, such as powerd, WindowServer and sharingd during Handoff, which hold sleep off for moments at a time. `pmset -g assertions` shows everything.
- Vitals does not show wake history. `pmset -g log` does.

Vitals is $9 during the launch, $29 after it, once: [vitalsmac.com](https://vitalsmac.com/).

## Questions people ask

### What is keeping my Mac awake?

Run `pmset -g assertions` in Terminal. Each line under “Listed by owning process” names an app, how long it has held sleep off and why. In Activity Monitor, the Energy tab’s Preventing Sleep column shows Yes for the same apps.

### Why won’t my Mac go to sleep when I close the lid?

On battery, a closed lid puts a MacBook to sleep whatever apps ask. With the lid closed on power and an external display connected, the Mac keeps running by design; Apple calls this closed-display mode. If it stays awake without those, check `pmset -g assertions` for PreventSystemSleep.

### Why does my Mac wake up by itself at night?

Usually for maintenance, network activity or a connected device. Run `pmset -g log | grep -E "Wake from|DarkWake from" | tail -20` and read the text after “due to”. Set Wake for network access to Only on Power Adapter if the network is the cause.

### How do I stop an app from keeping my Mac awake?

Close what it is doing, such as the video, the call or the download, or quit the app. For `caffeinate`, press Control-C in its Terminal window or quit the app that started it.

### Is it bad if my Mac never sleeps?

It costs power, and on a MacBook in a bag it builds heat and empties the battery. It does no harm on a desktop Mac you use as a server, as long as that is what you want.

### Is there an app that shows what is keeping my Mac awake?

On a MacBook, Vitals lists the apps keeping it awake on its Battery tab and in the menu bar dropdown, with the reason each gives, how long it has held sleep off, and whether it keeps the screen on.

In the glossary: [Preventing Sleep](https://vitalsmac.com/glossary/preventing-sleep), [Energy Impact](https://vitalsmac.com/glossary/energy-impact), [App Nap](https://vitalsmac.com/glossary/app-nap), [sharingd](https://vitalsmac.com/glossary/sharingd), [launchd](https://vitalsmac.com/glossary/launchd).

More guides: [Why is my Mac so slow](https://vitalsmac.com/why-is-my-mac-so-slow), [What’s draining my Mac’s battery](https://vitalsmac.com/mac-battery-draining-fast), [Which app is using my CPU or memory](https://vitalsmac.com/check-cpu-memory-usage-mac), [Chrome using too much memory](https://vitalsmac.com/chrome-using-too-much-memory-mac), [Why are my Mac’s fans so loud](https://vitalsmac.com/mac-fan-loud), [How to control fan speed on a Mac](https://vitalsmac.com/mac-fan-control), [How to free up RAM on a Mac](https://vitalsmac.com/free-up-ram-mac), [Docker using too much memory](https://vitalsmac.com/docker-using-too-much-memory-mac), [How to stop Docker containers](https://vitalsmac.com/stop-docker-containers-mac), [Volume mixer for Mac](https://vitalsmac.com/mac-volume-mixer), [Activity Monitor alternatives](https://vitalsmac.com/best-activity-monitor-alternatives), [iStat Menus alternatives](https://vitalsmac.com/best-istat-menus-alternatives), [Stats alternatives](https://vitalsmac.com/best-stats-alternatives), [Task Manager for Mac](https://vitalsmac.com/task-manager-for-mac), [Best system monitors for Mac](https://vitalsmac.com/best-system-monitor-for-mac), [Best menu bar monitors for Mac](https://vitalsmac.com/best-menu-bar-system-monitor-for-mac), [Best volume mixers for Mac](https://vitalsmac.com/best-volume-mixer-for-mac).