Bed bugs only feed on blood and humans are their preferred host. There is no evidence that they transfer diseases when feeding. Usually they eat at night but are most active the hour before sunrise. Under the right conditions, bedbugs can survive up to a year without a meal.
Bedbugs are hitchhikers. People pick them up when someone they contact infested clothing and furniture or when they bring infested items, such as a mattress, into their home. They are often found in hotels and multi-unit living where they can travel easily from room to room by getting into personal items like purses and luggage. Their small size allows them to sneak in unnoticed. Once inside your home they harbor in cracks and crevices, including mattress seems, furniture, behind baseboards, electrical outlets, and stored items.