How to keep your computer from sleeping

Change the sleep setting to Never in your power settings: on Windows, Settings → System → Power; on a Mac, System Settings → Lock Screen. If you only need the screen on while a clock or timer is showing, use the Keep screen on button on our clocks instead. It works only while the page is open.

Windows 11

Go to Settings → System → Power & battery (on desktops: Power).
Open Screen, sleep & hibernate timeouts (on some versions: Screen and sleep).
Set Make my device sleep after to Never (and Turn my screen off after too, if you want the display to stay on). Laptops have separate settings for “plugged in” and “on battery”.

Windows 10

Go to Settings → System → Power & sleep.
Under Sleep, choose Never. Under Screen, choose how long before the display turns off.

Mac

Open System Settings → Lock Screen and set Turn display off on power adapter when inactive (and, on a laptop, on battery when inactive) to Never.
On a MacBook, also open System Settings → Battery → Options and turn on Prevent automatic sleeping on power adapter when the display is off. On a desktop Mac the same option is under System Settings → Energy.
For a quick, temporary fix, open Terminal and run caffeinate -d; the Mac stays awake until you close that window or press Control-C.

Just keep the screen on while a clock is showing

Every clock and timer on this site has a Keep screen on option (in the controls under the clock). It uses your browser's Screen Wake Lock, supported in current Chrome, Edge, Safari and Firefox, to stop the display dimming while the page is open, and lets the computer sleep normally again when you close it. Going full screen turns it on automatically.

Sleep vs hibernate vs screen off

Screen off: only the display turns off. Everything keeps running, including clocks and alarms in your browser.
Sleep: the computer pauses and keeps your work in memory using a little power. It wakes in seconds, but web pages stop running.
Hibernate: the computer saves your work to the drive and powers off almost completely. It takes longer to wake but uses no battery.

Why not just turn sleep off forever?

A computer that never sleeps uses more electricity, and a laptop's battery drains quickly. Leaving the screen on for hours can also cause burn-in on some OLED displays. Using the clock's Keep screen on button, or a timer-limited setting, is usually the better balance.

Questions people ask

Why does my screen keep turning off?

Your power or lock-screen settings turn the display off after a few minutes of no keyboard or mouse activity. Increase the time or set it to Never.

Does Keep screen on work if I switch tabs?

No. Browsers release the wake lock when the page is hidden. Our clocks ask for it again automatically when you come back to the tab.

How do I take sleep mode off?

On Windows 11 go to Settings, System, Power & battery, Screen, sleep & hibernate timeouts and set the sleep options to Never. On a Mac, use System Settings, Lock Screen and Battery (or Energy) as described above.

How can I keep my computer from going to sleep without changing settings?

Leave a page open that holds a screen wake lock, such as any clock on this site with Keep screen on turned on, or run caffeinate on a Mac.

Will an alarm ring if my computer sleeps?

No. A web page can't wake a sleeping computer. Keep the computer awake, or use your phone's built-in alarm for anything important.

Sources

Last updated October 21, 2026. Menu names can differ slightly between versions. Found a step that's changed? Tell us.