If your PC screensaver keeps activating at awkward times, or maybe your system goes to sleep when it shouldn’t, then it may be a good time to adjust your power options (press Win+R and launch powercfg.cpl).

If you only have this problem occasionally, though – when giving a presentation, perhaps – then Caffeine provides a quick and easy way to temporarily keep your system awake.

The program is free, portable and extremely small (a 14KB download). Launch Caffeine and it goes to work immediately, simulating an F15 keypress every 59 seconds to persuade the system that you’re still at the keyboard.

Caffeine can be controlled from the command line, or a system tray icon

If this isn’t quite what you need, Caffeine can be turned on and off from a system tray icon. There are timed options, too, so you could perhaps set the program to be active for the next hour, and your normal power settings will return afterwards.

There are also several command line switches to help control how Caffeine works. You get options to choose which keypress is simulated, for instance, and how often it’s repeated. You can decide whether it’s active on launch, and how long the program will stay running. The program can be controlled from your system tray, or a taskbar button, and there’s even an option to prevent sleep, but allow the screensaver to start.

Caffeine would be a little easier to use if these settings were available from the GUI, of course, but you can still set them up from a shortcut within a few seconds. And this simplicity does at least make for a compact and very portable program, which consumes only 1.4MB RAM and, the author claims, runs on anything from Windows 98 upwards. Give it a try.