Use Caffeine To Keep Your PC Awake

Martin Brinkmann
Jul 27, 2008
Updated • Jul 10, 2017

Caffeine is a free program for Microsoft Windows devices that keeps your Windows PC awake so that it won't enter sleep or hibernate power modes.

I need a good strong cup of coffee usually in the morning before I start work. It is more of a tradition I guess than something that I cannot live without though.

Caffeine takes the concept of drinking a beverage with caffeine and applies it to the PC. It acts as a dose of caffeine that is administered to the PC in intervals so that it won't enter sleep mode.

Depending on how a Windows machine is configured, it may go to sleep automatically after a period of idle time. Idle time in this regard means little to no user interaction, and little background activity.


caffeine prevent sleep mode

Caffeine was designed to prevent this from happening. The free tool simulates a keypress every 59 seconds by default to prevent sleep mode. Keyboard activity prevents sleep mode from kicking in, and this is true for simulated key presses as well.

The default value can be changed to a keystroke every x seconds instead. To prevent problems with running applications the software simulates a shift-down, shift-up keystroke in Windows 98 and a shift-down keystroke in Windows XP and newer.

The program can be run with a double-click on the icon to run it with its default configuration, or with parameters to customize the functionality.

A click on the application's system tray icon displays options to enable or disable the program's functionality.

You find all parameters on the developer website but the most useful ones are (probably):

  • XX -- which is the time in seconds that the program waits before it simulates keypresses. This must be the first command.
  • -exitafter:xx -- terminates the program automatically after the specified time in minutes
  • -activefor:xx -- the program becomes active for the specified time in minutes
  • -inactivefor:xx -- application becomes active after the specified time in minutes.
  • -key:xx -- simulate the keypress using the specified virtual key code.


The software has a size of only 24 Kilobytes and can be useful if your computer falls asleep every now and then without you wanting that.

On the other hand, sleep and screensaver intervals can be changed as well or turned off. Caffeine is mostly useful therefore on systems where sleep mode is configured but needs to be blocked from kicking in at times.

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  1. random guy said on January 3, 2010 at 1:31 pm

    can you give a link to download your program rarst

    1. Rarst said on January 3, 2010 at 1:39 pm

      Don’t think I have bothered to post it anywhere, here is AutoIt code for it

      AutoItSetOption ( "TrayIconHide" , 1 )
      While 1
      $pos = MouseGetPos()
      MouseMove ( $pos[0]+1, $pos[1] , 0 )
      MouseMove ( $pos[0], $pos[1] , 0 )
      Sleep (600000)

  2. Rarst said on July 27, 2008 at 5:19 pm

    I think “keep computer awake” is like second most written program after “hello world”. :) It’s easy to do in any language and it’s really useful unlike “hello world”. :)

    Mine was AutoIt script that shakes mouse every few minutes – still use it at work.

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