This is a game changer! My SAD kicks in mid October and my wake up routine then consists of being unable to move or face getting up for at least 40 minutes after the alarm has gone off. This time is generally spent thinking of reasons I could call in sick to work for the indefinite future. I don't really understand the science behind this alarm but I've used it for a week now and cannot believe the change in me! The light doesn't wake me, it's the gentle sound that it gives off once the light has been on for 30 mins, however, now when I wake up, I'm really awake and able to get straight out of bed and get on with the day. This could be my favourite ever purchase.