Hamster sleeping at night

[Ria P]

I'd put a big heap of torn into strips, plain white toilet paper near her house for nesting material which may encourage her to make a nest inside the house.

All our hamsters have the Ferplast guinea pig houses but only the Syrians sleep in theirs and nowhere else.
The dwarfs change sleeping locations. Hamsters are very individual with different sleeping habits and patterns.
I sometimes get up during the night and cannot see one awake hamster.