Then you pay more attention to your family and feel homesick recently. Maybe you didn't notice, but subconsciously you did.
then what Maybe when you sleep, your hands are pressed on your chest, or you sleep with your head covered, which leads to poor breathing and easy nightmares.
There is no scientific explanation for dreams. Don't worry. In The Duke of Zhou, it is often said that it is a good sign to dream that one's family is ill or dead. You can check it out if you don't believe me.