Since 1991, Lumie have been researching and producing lights to tackle the symptoms of seasonal affective disorder (or S.A.D.) The Zest can be used as a wake-up light for a more natural start to the day, and it can also be used as a light therapy device to give you a boost in the winter months or if you are stuck indoors. Your body is hardwired to wake up to the gradual rise of the sun, but due to our busy modern lives this very rarely goes hand in hand with when you need to get up.