Phones can result in sleep deprivation and poor grades: When parents check their teen’s cell phone usage, they often find that their teen is taking calls at all hours of the day and night. Teens like to be in touch with their friends 24/7 and this behavior can leave your child sleep deprived, which can impact their grades in a negative way. A study done by the National Sleep Foundation found that 1 in 5 teens age 13 to 18 are awakened by a call or text message a few times a week.