Frequent waking in the middle of the night could hinder a person's ability to form new memories. That's according to a new study out of Stanford University. Researchers tested the effects of sleep interruption on lab mice by waking them frequently in the middle of their sleep cycle. They found the mice awoke with a sort of amnesia and had no apparent memory of the things they had learned the previous day. Researchers say the study adds new evidence to the existence of so-called "momnesia," in which new mothers often suffer through a mental fog until their little ones learn to sleep through the night. Lead researcher Asya Rolls notes that she, like many new parents, can hardly even remember the days of her children's infancy. The study appears in the journal "Proceedings of the National Academy of Sciences."