How much time do you spend on your tablet or mobile? Over a third of adults spend 4 to 6 hours a day on digital devices. Modern digital devices emit a fresh, bluish coloured light. Research suggests that using digital devices for prolonged periods at night could adversely affect sleep. The body's natural sleep patterns are governed by the release of a powerful chemical called Melatonin. As a result, lens manufacturers have developed blue light control lenses. Blue light control lenses are recommended for anyone using digital devices for long periods - particularly in the evening and at night.