About Blackout Blinds
Blackout blinds use design and blackout fabric to prevent light from entering a room through a window. They can be made of a blackout fabric or lined with it. The most popular design is a roller blind, because this simple style sits flat against the window frame and can usually be cut to fit. Another option is held in place by hook-and-loop or similar fixings to reduce light leakage around the edges.
Blackout blinds were originally used during the blitz to prevent light leakage from artificially lit buildings (such as homes) into the sky, making it more difficult for enemy aviators to see conurbations or target buildings. These wartime issue blinds were heavy and durable, usually of a utilitarian dark green colour, and may still be serviceable.
Modern blackout blinds are made in a range of fashionable colours designed to blend with any colour scheme, and are often chosen by insomniacs and shift workers to block out either night-time light pollution or inconvenient daylight. They can be useful to anyone who finds the natural influence of daylight on their sleep patterns clashes with their work or other daily routine, and may also help adults or children to sleep during the very light evenings of midsummer.
Although you can expect a blackout blind to significantly reduce the light levels in a room, if you find you are disturbed by any changes it's wise to use a blackout blind as part of a window treatment which includes heavy curtains, ideally also lined with blackout fabric.