Prevent your computer from going to sleep

If you have problems with your PC locking or going to sleep, caffeine will keep it awake. It works by simulating a keypress once every 59 seconds, so your machine thinks you're still working at the keyboard, so won't lock the screen or activate the screensaver.

The icon is shown above - it's the leftmost one in the task tray, and this is all you see. Double-clicking the icon empties the coffee pot (that's what the icon is) and temporarily disables the program. Double-clicking it again refills the pot, and will keep your machine awake.

By default the app starts enabled, and works every 59 seconds. There are some command line switches you can use to alter this behaviour:


Caffeine works by simulating an F15 key up event every 59 seconds. Of all the key presses available, F15 is probably the least intrusive, and least likely to interfere with your work.

However, Caffeine might interfere with some apps:

If you think any of these might cause you a problem, set the -useshift command line parameter.


Caffeine user humancar2n has put together a short YouTube video showing how the app works.

Mac version

Do you need this functionality on your Mac? Lighthead Software have written a separate app, also named Caffeine, which can help you out.


v1.90 - October 2020

-darkicons command line option added

-activehours command line option added

Tooltip replaced with a new one which works more reliably

Menu appearance updated

v1.81 - May 2020

Bug with the -watchwindow command line fixed

v1.80 - January 2020

v1.64 - September 2017

Option for old icons added, 'cos not everyone likes the new ones

v1.63 - February 2017

Icons updated slightly to show up better on a white background.

v1.62 - April 2016

New icons, designed by Rubén Gómez Radioboy

v1.61 - October 2015

Fixed bug with app not going active/inactive correctly when a timed period elapsed

v1.60 - July 2013

New command line options:

Added menu items to go Active/Inactive

Type in About box corrected

-apptoggle will re-show the dialog if it was originally shown

v1.50 - November 2010

New command line options:

Simulated keypress changed from right context menu key to F15 as this is likely to be even less intrusive.

v1.40 - July 2009

New command line options:

Hovering over the tray icon now shows the status of the app

v1.35 - May 2009

Simulated keypress changed from shift to the right context menu key (at the suggestion of Kevin Kleinfelter) as this is likely to be less intrusive.

v1.30 - February 2009

Command line switches added to terminate the app after x minutes, disable the app after x minutes, and enable or disable the currently running instance of the app

v1.20 - March 2008

Command line switches added to set the interval and to start disabled

Download Caffeine (x86 and x64)