You may have heard this before, but a doctor recommended to my sister, who also suffers seasonal depression, to increase the lighting in her house. The lighter and brighter the better, I guess to simulate sunshine. Little by little, she was able to tackle a room at a time in her house to paint and brighten it up. She rarely gets depressed anymore, and certainly not to the extent she used to.
Your quilt is just gorgeous, and if you don't keep it, it will certainly brighten someone's year!