### Instruction:
Why do people need sunshine?

### Response:
Ultraviolet waves from sunlight are absorbed through the skin as part of the process of producing Vitamin D. This is a critical vitamin for the immune system's ability to ward off disease, as well as for a person's hormonal balance. So sunshine can help make people both healthier and happier. On the other hand, too much sunshine can cause sunburn, which can make a person both unhealthy and unhappy.