Reasons Why Babies Cry at Night There are many reasons why babies cry at night. Here are some possible factors: Physiological Causes Babies may cry because they are feeling uncomfortable, such as hunger, an upset tummy, bloating, or developing teeth. These problems may cause them to be unable to sleep or wake up. Don\’t forget to check your baby\’s diaper to see if it needs changing. In addition, babies whose day and night are reversed may be because of