loss of leaves
 

I have a tree of a thousand stars and I am worried that it is loosing all of it's leaves, is this what happens in the winter.
Can anybody help me with this problem as I do not want to loose the tree if I can help it.
When I first got the tree I had it in the kitchen window and it was growing ok but we have the window open during the day even in the winter and I didn't know if the draught was effecting it so I moved it into the lounge out of the draught but it is still loosing it's leaves is this what normaly happens in the winter.