Why Won't My Mac Go to Sleep?

When a Mac refuses to sleep, something is holding a power assertion: a request to stay awake. You can see who is asking.

See what is blocking sleep

pmset -g assertions

Look at the assertions with a non-zero count, such as PreventUserIdleSystemSleep or PreventUserIdleDisplaySleep. Below the summary, macOS lists the owner, for example pid 123(caffeinate), and often the reason it gave.

To watch assertions being taken and released over time (this keeps running; press Control-C to stop it):

pmset -g assertionslog

Check why it woke up

pmset -g log | grep -E "Wake|Sleep"

Wake entries usually include a reason, such as lid open, a power-button press or network activity.

The usual causes

• caffeinate running in a Terminal tab. Stop it with Control-C in that tab.
• Video, calls or screen sharing, which keep the display and system awake on purpose.
• Downloads, backups or syncing in the background.
• A browser tab or app playing audio or holding a wake request.
• Settings that allow wake-ups, such as waking for network access. Look under System Settings → Battery (or Energy on a desktop Mac). The name and location vary by macOS version.
• Connected devices that send wake signals, such as some USB or Bluetooth accessories.

Fixing it

1. Find the process in the assertions list.
2. Quit that app, or end whatever started it.
3. Run pmset -g assertions again to confirm the count has dropped.

What this tells you, and what it does not

pmset reports what macOS recorded. A wake reason is a fact from the log; any explanation of why a device sent the signal is an inference.