SAD lights are used to treat seasonal affective disorder by providing bright light that mimics sunlight. These lights can help set the circadian rhythm and reduce depression, especially for people living at high latitudes.
These lights, especially in the morning, have a way of of not only setting your circadian rhythm and making sure it's on track, but also reducing depression.
""SAD lights are mentioned as a treatment for seasonal affective disorder and a way to regulate circadian rhythm, making them a potentially desirable product for listeners experiencing these issues."