If your PC goes to sleep fine but then turns itself back on a few minutes or hours later with nobody near it, a wake timer is almost always the reason. It's a scheduled task with explicit permission to pull Windows out of sleep at a specific time. Here's how to list what's armed, check what woke it last, and disable or restrict wake timers so it actually stays asleep.
Quick answer: Run powercfg /waketimers to see what's currently scheduled to wake your PC. To stop it, go to Control Panel → Power Options → Change plan settings → Change advanced power settings → Sleep → Allow wake timers, and set it to Disable or Important Wake Timers Only. Read on for what woke it last time, the usual culprits, and why disabling wake timers completely can occasionally delay Windows Update.
A wake timer is Windows' name for a scheduled task that's allowed to break sleep at a specific time, regardless of whether anyone's touching the PC. It's different from a device wake source — a mouse, keyboard, or network adapter that wakes the PC in response to activity. A wake timer fires on a clock, not on input, which is exactly why it can wake your PC at 3 a.m. with nothing around it moving.
Task Scheduler is the mechanism: any task with "Wake the computer to run this task" checked under its Conditions tab gets a wake timer registered for its next scheduled run. Most of them come from Windows itself — maintenance, Windows Update, disk checks — but backup software, antivirus scans, and some OEM utilities register their own too.
Open Command Prompt or PowerShell — no admin rights needed — and run:
| Command | What it shows |
|---|---|
powercfg /waketimers | Every wake timer currently scheduled, and the task behind it |
powercfg /lastwake | What woke the PC the last time it actually happened |
powercfg /devicequery wake_armed | Devices (mice, network adapters) allowed to wake it from activity, not a timer |
powercfg /waketimers only lists timers that are currently scheduled — if a task already ran and woke the PC once, it won't show up here afterward unless it's set to repeat. If the list comes back empty but your PC still wakes itself up, the timer already fired and is waiting for its next occurrence, or the cause is a device wake source instead — check wake_armed next.
If you just want to know who woke it up overnight without waiting for it to happen again, powercfg /lastwake is faster than digging through Event Viewer. It names the exact process, driver, or wake timer responsible for the most recent wake — run it first thing in the morning and it'll usually point straight at the culprit.
Control Panel → Power Options → Change plan settings → Change advanced power settings → Sleep → Allow wake timers. There are three options: Enable (any wake timer can fire), Important Wake Timers Only (Windows Update and a handful of critical tasks only), and Disable (nothing wakes the PC on a schedule, ever).
Best for: Most people — pick Important Wake Timers Only as a middle ground, or Disable if you never rely on scheduled backups or updates to run overnight. Note: Laptops and desktops set this independently for plugged-in vs. battery.
powercfg /setacvalueindex SCHEME_CURRENT SUB_SLEEP RTCWAKE 0 disables wake timers while plugged in; use /setdcvalueindex for battery. Index 0 is Disable, 1 is Enable, 2 is Important Wake Timers Only. Run powercfg /setactive SCHEME_CURRENT afterward so the change actually takes effect.
Best for: Scripting it once across multiple machines. Note: This changes the active power plan only — if you switch plans later, the setting doesn't follow.
When powercfg /waketimers or /lastwake names something, it's almost always one of these:
If the PC wakes but doesn't go back to sleep afterward, that's a different problem — something is holding it awake once it's up. See why Windows won't go back to sleep and how to find what's blocking it.
To be upfront about it: PowerDoze doesn't disable wake timers. That's purely a Windows setting, and the steps above are the real fix. What PowerDoze does is different — it schedules when the PC should sleep and which power mode it should be in at different times of day, so overnight sits on a short, aggressive sleep timeout instead of whatever the default happens to be. If a wake timer does still fire and pull the machine up early, having it already in a low-power mode limits the damage instead of letting a full-performance profile run unattended until morning.
Honest note: If your PC is waking itself up, fix it with the steps above — that's the actual cause. PowerDoze is for scheduling sleep behavior around the clock, not for controlling wake timers. Free for up to 3 time-based rules and 2 power modes, no account required.
A wake timer is permission Windows grants to a scheduled task or app to pull the PC out of sleep at a specific time, even with no one touching the keyboard or mouse. Task Scheduler, Windows Update, and disk maintenance are the usual sources. It's different from a device wake source like a mouse or network adapter — a wake timer is time-based, not activity-based.
Run powercfg /waketimers in Command Prompt or PowerShell. It lists every currently armed wake timer along with the task or driver that set it. If nothing is armed right now, it says so — a wake timer only shows up here while it's scheduled, not after it fires.
Run powercfg /lastwake. It names the specific process, driver, or wake timer that pulled the machine out of sleep most recently — useful after a PC wakes itself up overnight and you want to know who did it, without waiting for it to happen again.
Control Panel → Power Options → Change plan settings → Change advanced power settings → Sleep → Allow wake timers, then set it to Disable. From the command line: powercfg /setacvalueindex SCHEME_CURRENT SUB_SLEEP RTCWAKE 0 (plugged in) and powercfg /setdcvalueindex SCHEME_CURRENT SUB_SLEEP RTCWAKE 0 (battery), then powercfg /setactive SCHEME_CURRENT to apply it.
It's the middle setting between Enable and Disable. Windows still lets timers it considers critical wake the PC — mainly Windows Update maintenance and some security tasks — but blocks everything else, including most third-party scheduled tasks. It's the setting Microsoft recommends by default, and it's why disabling wake timers outright can occasionally delay updates.
No — wake timers are a Windows setting, and PowerDoze doesn't touch them directly. What PowerDoze does is schedule when the PC should sleep and which power mode it should be in at different times of day, so if something does wake it early, it can drop back into a low-power mode automatically instead of staying fully awake until morning.
Wake timers sorted, but still want overnight sleep behavior to be smarter than one fixed timeout? Time-based rules are free, up to 3 rules and 2 power modes, no account required.
Download free for Windows 10/11See also: Why Windows won't sleep · Change when Windows sleeps · Does Windows have a sleep timer? · All features