Some peoples teeth do move more when asleep but not always.
For some people they also have a problem with grinding of the teeth while asleep which is also known as bruxism.
The Bruxism can cause damage to the teeth and cause sensitivity to the teeth.
It can also cause cracks in your teeth so it's a good idea to wear a tooth protector at night if you have trouble with grinding your teeth.
Sometimes your teeth many shift or move at night without you even realizing it and it's usually nothing wrong to worry about.
If you're worried though you could see a dentist about it but it's normal for some people to have their teeth shift overnight.