Your Mac Sleeps and the AI Agent Drops? Use caffeinate to Keep OpenClaw and Hermes Running All Night

This one comes from a very real pain: you give an Agent a job that takes a few hours, step away for a coffee, and come back to find your Mac asleep, the task stopped halfway, and Telegram unable to wake it. Today I’ll show you a built-in macOS fix that takes a single line—caffeinate.

The symptom: it runs halfway, the Mac sleeps, and the Agent “blacks out”

You’ve probably seen one of these:

• You leave the OpenClaw Gateway running to receive Telegram/Discord messages. You step away, come back, and the messages never arrived.
• You hand Hermes a big task—organizing a batch of files, running a long analysis, maybe an hour or two. You come back and it’s stopped partway.
• You queue an automation overnight to run quietly, and in the morning nothing happened.

These all share one thing: the moment your Mac goes to sleep, the network connection drops, background programs are suspended, and the Agent effectively blacks out.

Why it happens: your computer defaults to “idle means sleep”

To save power, laptops ship with a default of “sleep automatically after a while with no activity.” That’s good for everyday use, but for an AI Agent that needs to stay on standby or run for a long time, it’s exactly the enemy.

Duck Editor’s take: Agents keep getting stronger, and we keep handing them jobs that take a long time. But your laptop defaults to “idle means sleep”—those two things are naturally at odds. The command below is what resolves that conflict.

First, get one thing straight: caffeinate keeps it awake, it doesn’t put it to sleep

Let me nail down the point most people get backwards:

caffeinate’s job is to prevent your Mac from sleeping—to keep it awake. Just like a person who’s had caffeine can’t sleep—which is exactly where the name comes from.

Get the direction wrong and the whole thing stops making sense. What we want is this chain: computer stays awake → connection doesn’t drop → the Agent’s service doesn’t get interrupted.

The fix: one line to keep your Mac awake

Open Terminal and type:

caffeinate

That’s it. As long as this command is running (the window is open and you haven’t pressed Ctrl + C), your Mac won’t sleep from being idle. To stop it, press Ctrl + C or close that terminal tab.

But that’s a bit clumsy—you have to babysit a window. Here are the more practical versions.

Breaking down the five -dimsu flags

You may have seen caffeinate -dimsu. That turns on all five switches. One by one:

Flag	What it does	In plain words
-d	Prevent the display from sleeping	Screen stays on
-i	Prevent system idle sleep	Won’t sleep even with no activity (the most used one)
-m	Prevent the disk from idle sleep	Disk won’t spin down
-s	Prevent system sleep	Only works on AC power
-u	Declare the user is active	Pretends you’re using the computer

A few details you must know:

• -s only works on AC power. On battery it won’t block sleep—that’s Apple’s design.
• -u on its own defaults to just 5 seconds (unless paired with -t), so it’s more of a “nudge the screen on” than a lasting effect.
• Most people don’t need all five. For running an Agent in the background, the key one is -i (block idle sleep); add -d if you also want the screen on to watch progress.

Three genuinely useful patterns

Pattern one: run a command to completion, then release (recommended). caffeinate can take a command right after it, and it ends the instant that command finishes—cleaning up for you:

caffeinate -dimsu your-startup-command

The computer stays awake exactly as long as the task runs; when the task ends, caffeinate exits too and your Mac can sleep normally again. No need to remember to turn it off.

Pattern two: hold out for a fixed time. Use -t to specify seconds—for example, 2 hours (7200 seconds):

caffeinate -i -t 7200

Pattern three: watch a process that’s already running. If the Agent is already running in the background, use -w to “wait” on its process ID (PID); it releases the moment that process ends:

caffeinate -i -w $(pgrep -f openclaw)

pgrep -f openclaw finds OpenClaw’s PID for you, and -w keeps an eye on it.

🚨 Common mistakes

Closing the terminal window = stopping the caffeine. caffeinate lives with that terminal window; close the window or restart the computer and it’s gone. To hold out in the background long-term, append & to push it to the background, or use nohup or tmux so it doesn’t die with the window.

Close the laptop lid and it’ll usually still sleep. This is the most common misunderstanding. caffeinate blocks idle sleep, but sleep triggered by closing the lid is a separate thing—under normal conditions the computer still sleeps when you close the lid even with caffeinate running (unless you meet specific conditions like AC power plus an external display). To run it for a long time, keep the screen on and don’t close the lid.

-s does nothing on battery. Mentioned above, worth repeating: to rely on -s to keep the whole system awake, stay plugged in.

It can’t fix the network itself dropping. caffeinate only keeps the computer awake. Flaky Wi-Fi, a router reboot, or your ISP hiccupping are separate problems—don’t blame those on it.

Prevention: first decide whether you truly need 24/7 awake

This trick is handy, but don’t blindly max it out. Keeping a Mac awake day and night has real costs: power draw, heat, battery wear, and a machine that’s always spinning. Here’s a checklist:

1. Occasional long tasks—use pattern one so it releases automatically when done; don’t leave it running forever.
2. Every day, staying on to receive messages / run schedules—this is the moment to think one level ahead: shouldn’t the Agent live on a machine that’s already on 24/7? A cheap VPS, an old computer, even a Raspberry Pi beats forcing your main laptop to tough it out.
3. Remember what caffeinate is for—it’s a “keep it awake temporarily” tool, not the right answer for “stand up a stable always-on service.” For genuinely long-running services, pmset, launchd, or just running on a server will be steadier than a single line of caffeinate.

Duck Editor’s take: matching the tool to the situation matters most. caffeinate is the fastest fix you can use tonight for “don’t let this long task get cut off”—and it does that beautifully. But if your need slowly becomes “I want an Agent that’s always online,” that’s no longer a stay-up-with-coffee problem—it’s time to find it a real bed (a machine that’s always on). Next time you hand a long task to OpenClaw or Hermes, wrap it with caffeinate -dimsu your-startup-command and go get your coffee in peace.