I purchased a light after my doctor recommended it to help with my SAD and poor sleep. After using the light for a week, I have definitely noticed that I seem to fall asleep more easily and--best of all--stay asleep more consistently through the night. I am also noticing less of a craving for coffee throughout the workday; I am doing just fine with just one cup in the morning. I will note the light seemed a little too intensely bright at first--I had the urge to put on sunglasses!--but with further use and adjusting the position I have gotten used to it. I am so pleased that I bought this light!