Keep your Mac awake for Claude Code, Codex and Cursor

Updated 11 August 2026 · 6 min read

Why this happens at all

It feels like a bug, but it's working as designed. macOS sleep timers are driven by human activity — keystrokes, trackpad movement, an app explicitly asking to stay awake. A terminal quietly burning CPU while an agent thinks does not count as activity.

So after your idle timer expires, the display sleeps. On Apple Silicon laptops the machine then slides toward standby, and that's where real damage happens: your process is suspended, open network connections drop, and the API stream the agent depends on dies. You come back to a half-finished run and a confused terminal.

This bites hardest on exactly the workloads people now run all day: long Claude Code sessions, Codex tasks, Cursor agents, big builds, model downloads, and test suites.

Option 1: the built-in caffeinate command

macOS ships with a tool for this and most people never hear about it. The cleanest form wraps the whole session:

caffeinate -dimsu claude

The Mac stays awake for exactly as long as that process lives, then sleep behaviour returns to normal on its own. No settings to undo. Here's what each flag actually does:

Other useful shapes — hold for two hours regardless of what you're running, or keep an already-running process alive by its PID:

caffeinate -dimsu -t 7200
caffeinate -dimsu -w 12345

The catch: you have to remember to do it, every time, before the run starts. Start the agent first and you're unprotected. Close the terminal tab and the assertion dies with it. And it does nothing for a closed lid.

Option 2: wire it into Claude Code hooks

If you want the Mac awake only while a turn is actually in flight, Claude Code's hooks can start and stop caffeinate around each turn — UserPromptSubmit to begin, Stop to release.

It's elegant, and it's the most power-efficient option. But be aware of the trade-off for unattended work: an agent loop has idle gaps between phases, and a per-turn hold lets the Mac sleep in exactly those gaps. For an overnight run you usually want the whole session held, not each turn.

Option 3: a menu-bar switch

The reason we built Awake: one click before you start, and everything in that window is covered — the agent, the build it kicks off, the download it triggers, the test run afterwards. Nothing to remember, nothing to type, no flags to look up.

It also handles the two things caffeinate genuinely can't:

• Lid closed. On power, keep the job running with the laptop shut — no external monitor needed.
• Knowing when to stop. It steps aside automatically at 20% battery, after a time limit, and if your Mac starts running hot.

Being straight with you: if you're happy typing caffeinate -dimsu claude every time, it genuinely solves the core problem for free, and you should just use it. Awake is worth paying for when you want it to be automatic, and when you want the lid-closed and safety-cutoff behaviour that the command line can't give you.

What about the lid?

This is where people get burned, so here's the honest physics. A closed laptop traps heat against its own body — that's precisely why macOS sleeps on lid-close when you're unplugged. It's a safety decision, not an arbitrary limit.

• Lid open, any power source — completely safe, vents normally. This is the default answer.
• Lid closed, plugged in — safe. It can vent and charge. Ideal for overnight runs.
• Lid closed, on battery — the risky one. Macs with fans cope; a fanless MacBook Air sealed in a bag can get warm. Only do this with a tool that watches the temperature and stops on its own.

Check that it's actually working

Don't trust it blindly — verify. This lists every active power assertion, so you can see exactly what's holding your Mac awake and which process owns it:

pmset -g assertions

Related: the complete caffeinate guide · keeping your Mac running with the lid closed · Awake vs Amphetamine · all comparisons