Why your MacBook battery drains overnight while asleep, and how to see what woke it
A sleeping Mac still wakes itself. Ours logged 49 dark wakes in two days, most for scheduled maintenance. How to read the wake log and cut overnight drain.
Why does my Mac's battery drain while asleep?
macOS wakes the Mac briefly, without turning the screen on, to check mail, sync iCloud, run backups and do maintenance. These are DarkWakes. Each is short; dozens a night add up, and any app holding the Mac awake makes it worse.
How do I see what woke my Mac?
pmset -g log | grep -E 'DarkWake|Wake from' | tail -20| From our Mac's log, two days | Count |
|---|---|
| DarkWake entries | 49 |
| Typical DarkWake length | 5 to 6 seconds |
| Most common reason | rtc/Maintenance, a scheduled maintenance wake |
| Other reason seen | wifibt, the Wi-Fi and Bluetooth chip |
A line such as DarkWake from Deep Idle ... due to ... rtc/Maintenance Using BATT (Charge:38%) 6 s reads as: woke from deep sleep, because of a timer for maintenance, on battery at 38%, for 6 seconds.
How do I reduce overnight drain?
- Turn off wake for network access: System Settings, Battery, Options (wording varies by Mac).
- Turn off Power Nap if your Mac offers it; see Power Nap and battery.
- Quit apps that keep the Mac awake before closing the lid; pmset assertions shows which do.
- Unplug accessories: USB devices and Bluetooth peripherals can wake the Mac.
See it live
Free Mac's System tab shows what the Mac is drawing from the adapter and the battery, and ranks what is draining it by energy impact, every second. See also what drains a MacBook battery and pmset sleep settings.
Related: Mac battery time remaining is wrong and use caffeinate.
Common questions
Why does my MacBook battery drain overnight?
macOS wakes the Mac briefly, DarkWakes, for maintenance, mail and sync. Apps holding it awake add more.
How do I see what wakes my Mac from sleep?
Run pmset -g log | grep -E 'DarkWake|Wake from' | tail -20 in Terminal. Each line gives the reason.
How many DarkWakes are normal?
Ours logged 49 in two days, 5 to 6 seconds each. Wakes every few minutes all night are not normal.