1. Are there any pets such as cats and dogs at home? Maybe they make a loud shit at night without realizing it.
2. Have you seen horror movies recently? Maybe it's because of my own psychology. I take the sounds in other places, such as the wind, as if the stool rang at night.
3. There is also hanging, which may be caused by mental or feng shui problems. But I think the first two reasons are more likely.