Dogs and cats can create a sense of safety and comfort for some people. The rhythmic heart beat and breathing from the animal can help a person fall asleep.
But pet dander and dirt in the bed can also trigger allergies. And, if you already have allergies, keeping the pet out of the bedroom can help give the body a few hours of recovery from allergic reactions.
Experts also say it is never a good idea for a pet to sleep in the same bed as an infant.