Q.Madagascar jewel
It’s November in Michigan and, as like last year, some leaves turn yellow and fall off my Madagascar Jewel. Should I be watering the plant now (once a week, very little water) or not at all for the winter? I keep the house quite cool 65 at night, is this ok? It gets some light from the sky light in the afternoon or should it be in a darker spot?

Certified GKH Gardening Expert
This is one of the many species of euphorbia. Most plants in this family are extremely high light requirement plants. This one can handle a little less light, but from what you have explained to me I believe I can tell you what it going on.
The leaves will tend to fall off, and change colors as the light hets less intense, and in less duration during the winter months. They are also a little sensitive to the cold. If it hasn't died, then it will be able to handle your environment. It seems that you have found the tipping point of what the plant can handle. Just keep an eye on it, and if it gets too bad, then you will want to put it in a better lit and warmer spot if possible.
Most species of this plant are, in fact, cacti. Some are DEADLY trees that simply breathing the sap will cause death. Almost all of them have a sap that is somewhat irritant. This is one of the most interesting and diverse genus of plants, and I don't see this often as a houseplant. Very Interesting!