What is preventing your Mac from sleeping?

Check sleep and sharing settings first

Review Lock Screen and Battery or Energy settings in System Settings. Options that prevent automatic sleep while the display is off, allow wake for network access, or keep services available may fully explain the behavior.

Also check General → Sharing. File sharing, media sharing, and printer access can legitimately keep the Mac available.

Rule out normal activity and devices

Media playback, a call, backup, transfer, export, or Spotlight indexing may keep a Mac awake for a valid reason. If the problem began after connecting USB or Thunderbolt hardware, disconnect nonessential devices one at a time and test again.

Check the current app-level blocker

A Yes value does not prove the app is defective. Force quit is a last resort because it can lose unsaved work or affect related processes.

1. Open Activity Monitor and select Energy.
2. Inspect the Preventing Sleep column while the problem is happening.
3. Confirm whether the named app is doing work you expect.
4. Save open work, quit the app normally, and test sleep again.

Find active blockers with KernPulse

KernPulse checks recognized, currently active macOS sleep-prevention requests. When it finds a user-visible process holding one, a diagnostic card names the process. This helps with intermittent problems that disappear before you open Activity Monitor.

The card is evidence of an active request, not proof of a bug. KernPulse does not end or pause an app without confirmation or a revocable rule you explicitly created.

Know what this check cannot explain

An active blocker scan does not reconstruct historical wake events. It may not explain a Mac that sleeps correctly and later wakes because of network access, input hardware, a connected device, or a scheduled task. If no blocker appears, return to Apple’s setting, sharing, device, and software checks.