# Why Won't My Mac Go to Sleep and How to Find the Cause

> pmset -g assertions names the process keeping your Mac awake. How to read it, the usual causes, and what to do when sleep is switched off.

Published: 2026-11-09

If your Mac will not go to sleep, one command usually names the cause. Run `pmset -g assertions` in Terminal, and look for lines with `PreventUserIdleSystemSleep` or `PreventSystemSleep`: each one names a process that is holding the Mac awake. Most of the time it is an app playing media, a remote access tool, a keep-awake utility or a download. Quit that one thing and the Mac sleeps again on its own.

## Find what is keeping it awake

The quick answer first. This line says which processes are preventing sleep:

```bash
pmset -g | grep -E '^ *sleep'
```

For example, this Mac printed `sleep 1 (sleep prevented by caffeinate, powerd, Amphetamine, ...)`. For the detail, including how long each has been holding on:

```bash
pmset -g assertions
```

A real line from the same Mac:

```text
pid 1321(UURemote): 36:07:42 PreventUserIdleSystemSleep named: "UURemote Disable Idle System Sleep"
```

The manual page (`man pmset`) says assertions "may prevent system sleep or display sleep". These are the ones to read:

| Assertion | What it blocks | What usually holds it |
| --- | --- | --- |
| `PreventUserIdleSystemSleep` | The Mac sleeping when idle | Media playback, downloads, remote access, keep-awake tools |
| `PreventUserIdleDisplaySleep` | The display turning off when idle | Video, presentations, keep-awake tools |
| `PreventSystemSleep` | Sleep more broadly | A system task or a tool asking for it |
| `UserIsActive` | Idle timers, for a short while | You just touched the keyboard or trackpad |

Most of these are idle blocks, so choosing **Sleep** from the Apple menu generally still works. If it does not, read on.

## Go through the usual causes

| Process or sign | Why | What to do |
| --- | --- | --- |
| `coreaudiod` | Audio is open, sometimes a paused tab | Close the tab or the player |
| A browser or video app | Video is playing | Stop it or close the page |
| `caffeinate`, Amphetamine and similar | They exist to keep the Mac awake | Quit them, or end that session |
| UU Remote, screen sharing or other remote tools | They keep the Mac reachable | Disconnect or quit them |
| Backup and sync apps, `bird` | A job is running | Let it finish, or pause it |
| `powerd` | Its own record, often while the display is on | Check the other lines first |
| `SleepDisabled 1` in `pmset -g` | Sleep is switched off for the whole Mac | See below |

Settings also matter. Open **System Settings › Battery › Options** and check **Prevent automatic sleeping on power adapter when the display is off**. **Wake for network access** on the same page decides whether the Mac wakes to serve shared resources. If the Mac wakes soon after you put it to sleep, an accessory is a common suspect, so unplug USB devices and hubs and test again.

## When sleep is switched off completely

`pmset -g` lists a `SleepDisabled` line. When it reads `1`, the Mac will not sleep, even from the menu or with the lid closed. Keep-awake tools set it to stay on with the lid shut, and it should go back when they stop. Quit those tools first. If it still reads `1` and nothing needs it:

```bash
sudo pmset -a disablesleep 0
```

Restart if you are unsure which tool set it.

## Lid closed and still running

A laptop with an external display, power and a keyboard or mouse can run with its lid closed. That is clamshell mode and it is deliberate, so unplug the display to test. If a MacBook stays warm in a bag, do not leave it there. Open it, run the commands above and find the process, since some tools keep the Mac awake through a closed lid on purpose.

## What not to do

- Do not reset the SMC or NVRAM first. Nearly all cases are one running process, and the command above takes seconds.
- Do not use random `pmset` changes from forums. They persist across restarts and are easy to forget. `pmset -g custom` shows what is set, and `sudo pmset restoredefaults` puts them back.
- Do not delete `sleepimage` to fix this. That file [is not what keeps a Mac awake](https://mole.fit/blog/what-is-sleepimage-mac).
- Do not ignore a hot MacBook in a bag. Take it out and let it cool first.

## Where Mole fits

In [Mole](https://mole.fit/)'s **Status**, **Why is this running?** in a process's menu reads the same assertions, and when that process holds the Mac awake it says "Process is currently preventing sleep." That helps once you suspect one app. For the full list at once, `pmset -g assertions` is still quicker. Mole's own **Keep Screen On** is one of the tools that holds an assertion, on purpose, and in its default mode, which also covers a closed lid, it uses `disablesleep`, which it undoes when the session ends. If you want the opposite of this page, see [keeping a Mac awake without draining the battery](https://mole.fit/blog/keep-mac-screen-on-without-draining-battery). If the battery falls overnight, see [why a MacBook battery drains fast](https://mole.fit/blog/macbook-battery-draining-fast).

## FAQ

### Why won't my Mac go to sleep?

Usually a process is holding a power assertion, such as media, a remote access tool or a keep-awake app. `pmset -g assertions` names it.

### How do I see what is preventing sleep on my Mac?

Run `pmset -g assertions` in Terminal and read the `PreventUserIdleSystemSleep` and `PreventSystemSleep` lines, which name each process.

### Why does my Mac wake up right after sleeping?

Accessories and network wake are the common suspects. Unplug USB devices and check **Wake for network access** in **System Settings › Battery › Options**.

### What is coreaudiod preventing sleep?

Something has audio open, often a browser tab or a music app, even when paused. Close it and the assertion should go away.

### What does SleepDisabled mean?

Sleep is switched off for the whole Mac, usually by a keep-awake tool. Quit that tool. If it stays at `1`, run `sudo pmset -a disablesleep 0`.

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