Why does my Mac lose battery while it's asleep?

Updated 11 November 2026 · Who measures this.

Some of it is normal: roughly 0.3 percentage points an hour while the Mac is truly asleep. Above that, something woke the Mac or kept it awake, and macOS keeps the name of what did it in a log it never shows you. If you closed the lid at 92% and opened it 9 hours later at 77%, that is about 1.7 points an hour, and this page gives you the arithmetic to judge it and the way to find the name.

First: is your overnight battery drain actually abnormal?

Divide the points lost by the hours the lid was closed, then read the table.

Apple publishes the sleep figure in its environmental reports: 0.22 W asleep for the 14-inch MacBook Pro (M4) and 0.40 W for the 16-inch (M4 Pro), measured with the Mac on its charger, the battery full and Wake for network access on. On those packs it works out, by our arithmetic, to roughly 0.3 percentage points per hour, so pure sleep across a 9-hour night is around 3%. The scheduled wake-ups below come on top of that.

The same watt costs a different percentage on different Macs. A 13-inch Air carries about 54 Wh and a 16-inch Pro 100 Wh, so on a small pack read the bands generously. And if the Mac was warm in the morning or the fans had run, skip the division: it wasn't asleep.

Your Mac wakes several times a night, sometimes dozens, silently

A sleeping Mac wakes on a schedule to do maintenance, then goes back to sleep, without the screen or a sound. On the Mac we measured, over 6 nights:

Quiet housekeeping of 19 minutes a night is the normal case. The abnormal case looks the same in the Battery Status menu and completely different in the log: one service waking the Mac hundreds of times, or holding it awake for many minutes at a stretch.

Who's asking: the answer macOS doesn't show you

macOS records every scheduled wake and the task that requested it. On the Mac we measured, all 73 timer wake-ups over 6 nights traced to a named service or daemon (the other 15 of the 88 came over the network, so nobody asked), and the biggest requester was search indexing, followed by disk-encryption health reporting, the power daemon, widget timeline refreshes and the Calendar.

A second Mac, a 14-inch MacBook Pro with M1 Pro on macOS 26.3, gave a different answer entirely over 7 nights: a median of 56 wake-ups a night instead of 5.5, each 5 seconds long instead of 45. The answer is specific to your machine, so the only list worth acting on is your own.

Full numbers, method and the top requester table are in our night-wake study, including the command to run the same analysis on your own Mac in Terminal.

WattMate does this reading for you: for each night it says how long the Mac actually slept (not just how long the lid was closed, which is a different number), how many times it woke, and which services asked. That works whether the night was on battery or on the charger. The latest night is free; every earlier one comes with Pro. The App Store edition can't read this log, so it shows how long the Mac slept but not who woke it.

The usual suspects, in the order worth checking

1. Something kept the Mac awake. An external display, a hub or an app that Activity Monitor shows as Preventing Sleep. If the Mac was warm in the morning, start here.
2. A device charging from the Mac. A phone in the USB-C port draws from the battery even while the Mac sleeps: what that cost in the night we measured.
3. Power Nap. On battery it lets the Mac check Mail and refresh Calendar and iCloud in its sleep. If you'd rather have the charge, Apple's guide for macOS 14 to 26 puts the setting in System Settings → Battery → Options (Enable Power Nap), where your Mac offers it; its guide for macOS 27 no longer lists one there.
4. Wake for network access. It lets the Mac wake to serve shared resources over the network, and on a busy network it adds wake-ups. On battery it does so only if it is set to wake always, not just on the power adapter.
5. A misbehaving background service. A specific requester appearing hundreds of times, or holding the Mac awake for minutes. You have to read the log for this one.
6. Battery age. A pack with high cycles gives up percentage faster everywhere, including at night. Check health before blaming sleep.

Reinstalling macOS isn't on this list, and neither is resetting the SMC on an Apple silicon Mac: Apple's own instruction there is just to restart or shut down with the Mac plugged in, and the SMC resets itself. Measure first, then change one thing.

Questions people ask

How much battery should a Mac lose overnight?

Roughly 0.3 percentage points per hour while genuinely asleep, so around 3% across a 9-hour night on a mid-size pack and more on a small one, plus whatever the scheduled wake-ups cost. Much above that means it wasn't really asleep.

Why is my Mac warm after being closed all night?

Because it was awake, not asleep. Something either prevented sleep or woke it repeatedly. The power log names the requester.

Does closing the lid put a Mac fully to sleep?

Not entirely: scheduled maintenance wakes are by design, and every one on the M3 Max we measured was silent. The log tells you whether yours are few.

Is turning off Power Nap worth it?

If overnight charge matters more to you than waking up to fetched mail, yes. It's a trade, not a bug fix. On macOS 27, Apple's guide no longer lists a Power Nap setting in System Settings.

How it was measured

What this doesn't show

• What one wake-up costs. macOS keeps a finer reading than whole percentage points, in milliamp-hours, but the battery publishes it only about once a minute, it wobbles, and it bounces back for minutes after the Mac wakes. A 45-second wake is lost inside that. Anyone giving you milliwatt-hours per wake-up is modelling, not measuring.
• Your own list of requesters. It is specific to each Mac. What can be read is how long the Mac slept, how often it woke, for how long, who asked and what the whole night cost.

Related: the night-wake study, with the raw numbers · why charging says "on hold" · what to expect after the macOS 27 update