Digital clocks have become the standard for alarm clocks. There are many iterations, LCD (Liquid crystal display), LED (Light emitting diode) and VFD (Vacuum florescent display). Sometimes the displays on these clocks are too bright in a dark room. Some clocks have a feature to turn down the display's brightness. For the clocks without that feature, you can reduce the intensity of the display yourself.
Measure the size of the display you wish to cover with a ruler.
Transfer the measurements to the window tint and cut it out with scissors.
Wash the piece of window film with soap and water. Dry the window film with a lint-free cloth.
Place the film over the display, starting at one side and slowly pushing it over to the other side. If you get air bubbles under the film, peel it back to before the bubble's location and try again. You have now darkened the display on your clock.
Apply the film slowly to avoid air bubbles.