Mac Battery Draining While Asleep on macOS 27: Fixes

Updated 2 November 2026. Checked against Apple's battery settings help for macOS and current reports from MacBook owners after the macOS 27 update. The same steps work on macOS Tahoe (macOS 26).

Short answer: a MacBook should lose only a few percent overnight with the lid closed. If yours is losing 20% or more, something is waking it up. Open Terminal, run pmset -g log to find out what, then turn off Wake for network access and Power Nap on battery. That fixes most cases.

Since macOS 27 "Golden Gate" arrived on 14 September, there have been plenty of complaints about this. An Apple Support Communities thread about severe drain on M5 MacBook Pros after the update had more than 70 "me too" votes by mid-October. One Reddit user said their M5 Pro went from 80% to 8% in a bag, with thousands of wake events logged. Not every Mac is affected, but if yours is, here's how I'd track it down.

Jump to:

• How much drain is normal
• Step 1: Find out what is waking your Mac
• Step 2: Turn off Wake for network access
• Step 3: Turn off Power Nap on battery
• Step 4: Check what is keeping it awake
• Step 5: Unplug accessories and Bluetooth devices
• Step 6: Turn off TCP keepalive (last resort)
• Step 7: Update macOS and reset the basics
• Common causes table
• FAQ

How much drain is normal

Apple silicon Macs are very efficient asleep. In my experience a closed MacBook Air or Pro loses roughly 1% to 5% over a night. It isn't completely off: it still checks for mail, iCloud changes and Find My now and then. Anything over about 10% overnight is worth looking into, and 30% or more means something is clearly wrong.

It's also worth knowing what changes when you plug in. Many of the settings below only apply on battery, because a Mac on power is allowed to wake more often.

Step 1: Find out what is waking your Mac

Before changing anything, find the culprit. macOS logs every wake. Open Terminal (in Applications > Utilities) and paste this:

pmset -g log | grep -e "Wake from" -e "DarkWake" -e "due to"

You'll get a long list. Look at the entries from last night. Each line says what triggered the wake, for example:

• DarkWake means the Mac woke briefly in the background without turning on the screen. A handful a night is normal. Hundreds is not.
• due to ... RTC/Maintenance is a scheduled check, usually Power Nap or a background task.
• wifibt, Wi-Fi or network points at Wi-Fi or Bluetooth waking the Mac.
• EC.LidOpen or UserActivity is you, so ignore those.

Since macOS 27, a common pattern in reports is a DarkWake every 15 minutes or so tagged wifibt or SMC.OutboxNotEmpty. If that's what you see, Steps 2, 3 and 5 are the ones to focus on.

To see how many wakes there were in total, run:

pmset -g log | grep -c "DarkWake"

Step 2: Turn off Wake for network access

This setting lets other devices on your network, like a phone streaming to a shared drive, wake the Mac. It's useful on a desktop and rarely needed on a laptop.

1. Open System Settings > Battery.
2. Click Options at the bottom.
3. Set Wake for network access to Never or Only on Power Adapter.
4. Click Done.

Step 3: Turn off Power Nap on battery

Power Nap lets a sleeping Mac check mail, update iCloud and make Time Machine backups. On some Macs it's on by default even on battery. In the same Battery > Options panel, turn off Power Nap if you see it, or set it to power adapter only.

If the option isn't shown on your model, you can switch it off for battery from Terminal:

sudo pmset -b powernap 0

The -b means battery only, so it still works when you're plugged in. Type your Mac password when asked (nothing appears as you type).

Step 4: Check what is keeping it awake

Sometimes the problem isn't waking up but never fully sleeping. An app can hold an "assertion" that stops sleep. Run this while the Mac is awake:

pmset -g assertions

Look under Listed by owning process. Things like a video app, a backup tool, a sync client or a stuck print job can show up with PreventUserIdleSystemSleep or PreventSystemSleep. Quit that app before closing the lid, or check its settings for a "prevent sleep" option.

Some macOS 27 users have also pointed at background processes such as replicatord and agentstored using CPU around sleep. You can check for them in Activity Monitor on the Energy tab. There isn't an official fix for those yet, so don't try to delete system files. Just note it if you report the issue to Apple.

Step 5: Unplug accessories and Bluetooth devices

USB hubs, external drives, docks and Bluetooth devices can all wake a Mac or stop it sleeping deeply. As a test, unplug everything and turn off Bluetooth before closing the lid for one night. If the drain stops, add things back one at a time to find the one causing it.

A paired Bluetooth keyboard or mouse that's left on in your bag is a classic one. Turn it off when you pack up.

Step 6: Turn off TCP keepalive (last resort)

TCP keepalive keeps some network connections open while the Mac sleeps. It's one of the main reasons for regular network DarkWakes. You can turn it off on battery with:

sudo pmset -b tcpkeepalive 0

macOS will warn you that this may affect some features, and it can. Find My may not update your Mac's location while it's asleep, and you may get messages and mail a little later when you open the lid. I'd only use this if the steps above didn't help. To undo it, run the same command with 1 instead of 0.

To see all your current power settings, battery and charger, run pmset -g custom.

Step 7: Update macOS and reset the basics

• Install updates. Go to System Settings > General > Software Update. Apple usually fixes widespread battery bugs in point releases, so stay current.
• Restart properly. If your Mac has been asleep for weeks, a restart clears stuck processes.
• Reset power settings. If you've tweaked a lot with pmset, sudo pmset -a restoredefaults puts everything back to Apple's defaults.
• Check battery health. In System Settings > Battery, click the info button next to Battery Health. A worn battery makes any drain feel worse.

If nothing helps and the log shows constant wakes, report it through Apple's Feedback Assistant app or contact Apple Support. Include the output from Step 1.

Common causes table

Related guides: I keep the main iPhone and Mac walkthrough in my guide to freeing up iPhone storage without deleting photos. You might also want my notes on fixing Siri setting the wrong alarm time or an iPhone screen that wakes up dim.

FAQ

Is it normal for a MacBook to lose battery overnight?

A little, yes. A few percent overnight is normal because the Mac still does small background tasks. Losing 10% or more with the lid closed usually means something is waking it up.

Does macOS 27 cause battery drain?

For some people, yes. After any big update, macOS reindexes files and photos for a day or two, which uses more power. Beyond that, there are many reports of sleep drain on macOS 27, especially on M5 MacBook Pros, and Apple hasn't confirmed a cause yet.

Will turning off Power Nap stop my email updating?

Only while the Mac is asleep. Mail, Messages and iCloud catch up within seconds when you open the lid.

Is it safe to change settings with pmset?

Yes, for the settings in this guide. They only change when the Mac wakes. You can undo everything with sudo pmset -a restoredefaults.

More help

If your iPhone is draining too, see my guide to fixing iOS 27 battery drain. Apple also explains each option in its guide to changing battery settings on Mac.