Why will my laptop not wake up from sleep?

A laptop that will not wake looks identical whether it is in a deep sleep state, has crashed, has run the battery flat, or has simply woken with the screen still off. They need different responses, and the reason people end up holding the power button unnecessarily is that the diagnostic signs are quiet ones — a light, a fan, a warm patch.

Step by step

1. Wake it properly and wait.Press a normal key such as shift, or the power button briefly, then wait a full thirty seconds. Deeper sleep states restore from disk and are not instant. Repeatedly tapping keys in the meantime achieves nothing.
2. Look for signs of life.A pulsing or steady power light, a warm underside, a fan you can hear. A machine that is warm and lit is running with the display off, which is a different problem from one that is cold and dark.
3. Rule out the display specifically.Turn the brightness up, and press the key that cycles the display output — laptops have one, usually on the function row. A machine that has sent its picture to a disconnected external monitor looks exactly like a machine that has not woken.
4. Rule out a flat battery.Plug the charger in, check its light comes on, and leave it for fifteen minutes before trying again. A deeply discharged battery may need time before the machine will start at all.
5. Force a restart only when the rest has failed.Hold the power button until the machine switches off, usually about ten seconds. Wait half a minute, then start it. It is safe as a last resort and risks only unsaved work.
6. Check what it did on the way in.If it went to sleep by closing the lid, by a timer, or by being told to, that is normal sleep. If it went dark on its own while in use, that was not sleep — it was a crash or a shutdown, and the diagnosis is different.
7. Update the graphics and chipset drivers.This is the most common cause of a repeat offender. Sleep and wake are handled largely by the graphics driver, and a bad or outdated one produces exactly this symptom.
8. Turn off fast startup if the machine misbehaves at every start.Fast startup keeps part of the system state on disk rather than shutting down fully. It is a known source of odd wake and shutdown behaviour, and turning it off costs a few seconds at boot.
9. Find out what is waking it, if it wakes on its own.A mouse nudged by a cable, a network adapter set to wake the machine, or a scheduled task will do it. In the device settings each peripheral has an option controlling whether it may wake the computer.
10. Consider whether it is sleeping at all.A laptop that is hot in a bag has not slept — it has stayed awake with the lid shut, which is a different fault and a genuine risk of overheating. Check the setting for what closing the lid does.

Tips

• If it only fails to wake when docked or with an external monitor attached, the dock, its cable or the graphics driver is the place to look rather than the laptop's sleep settings.
• Set the machine to hibernate rather than sleep for long periods. It writes everything to disk and powers down fully, which avoids both the flat battery and the failed wake.
• A machine that will not wake once is not a fault. A machine that will not wake weekly is, and it is worth working through the driver and fast-startup steps rather than living with it.

Common mistakes

• Holding the power button as the first move — It loses unsaved work and tells you nothing about the cause. Thirty seconds of waiting and a look at the power light cost nothing and often make it unnecessary.
• Carrying a laptop in a bag without checking it slept — A machine that stayed awake with the lid closed cooks itself in an enclosed bag and drains flat. If it is regularly hot on arrival, the lid setting or the sleep behaviour needs fixing.

If it doesn't work

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