Sunlight and Vitamins

The books say that sunlight is extremely dangerous, if it over heated in here, well lets say that we are meant to live underground. So we need to keep the curtains drawn. But isn't the Sun supposed to give you vitamin D? As it goes, we cannot escape some sun in this plastic house.
Zsa-Zsa is happy to escape her dwelling and explore. She has also become quite friendly and happy to see people. It takes about two weeks til a hamster is trusting and calm around it's new surrounding.