I always feel more cheerful on a sunny day; I am warmer, and happier. The flowers are pretty, the birds are singing. Then there is the physiological effect. The brighter light will stimulate your pineal gland more effectively, producing ‘wake up’ hormones. Because my mood is enhanced, I am more likely to get up and do something. If I get active, my adrenalin levels rise, which also make me feel good. I might even take the children to the park, making us happy as a family (I might not, though, don’t get too excited). It gets better and better.