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Sleep & battery · P3

Find out what kept your Mac awake last night.

iKnowMyMac shows which apps are preventing sleep right now, why your Mac woke up, which apps drained the battery overnight, and how battery health changes over time.

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“Lost 14% overnight: Docker kept your Mac awake for 2h 10m”

The problem

You closed the lid at 80%. It was 66% in the morning.

Activity Monitor's Preventing Sleep column shows what is blocking sleep now, not what happened at 3 am. The power log has the answer, buried in thousands of lines of pmset -g log.

  • A warm MacBook in a bag that was supposed to be asleep
  • Double-digit battery loss overnight
  • No idea whether it was an app, a wake request or the network
The Sleep & Battery screen with simulated data: last night's sleep, dark wakes, and drain by app.

How it works

Three steps, no setup

  1. 01

    It watches sleep assertions

    iKnowMyMac records which apps hold a sleep assertion (the request that keeps a Mac awake) and for how long.

  2. 02

    It reads the wake log

    With the optional read-only helper, it parses the power log and lists every wake with its reason, including dark wakes where the screen stays off.

  3. 03

    You get the overnight report

    How much battery you lost while asleep, which apps used it, and what kept the Mac awake.

Details

What you get

  • Keeping your Mac awake now

    Every app holding a sleep assertion, what kind (system or display sleep) and for how long.

  • Why it woke up

    A timeline of wakes and dark wakes with their reasons, read from the power log through the helper.

  • Overnight drain by app

    Which apps used the battery while the lid was closed, as a share of the loss.

  • Battery health trend

    Maximum capacity and cycle count over time, so a slow decline is visible before it matters.

  • Accessory batteries

    Battery levels for Bluetooth keyboards, mice and trackpads.

  • Read-only helper

    The optional helper can read the power log but cannot run commands or change anything. Sleep blockers and drain by app work without it.

FAQ

Questions

Something else? support@iknowmymac.com

Do I need to install the helper?

Only for wake reasons, which come from the system power log. What's preventing sleep and overnight drain by app work without it. The helper is read-only: it can't run commands or change anything.

What is a dark wake?

A wake where the Mac does work with the screen off, for example network maintenance or Power Nap. See dark wake in the glossary.

Can I check this without iKnowMyMac?

Yes. pmset -g assertions lists sleep assertions now, and pmset -g log has the wake history. Our overnight battery drain guide walks through both.

Does it work on desktop Macs?

Sleep assertions and wake reasons work on any Mac. Battery drain and battery health need a Mac with a battery.

Know why your Mac is slow.

macOS 15 Sequoia or later · Apple silicon. A 4.2 MB native app, notarized by Apple. No account, no analytics, no telemetry.

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One-time purchase · every feature · 14-day refund