Train your four-month old to sleep through the night. Sleep experts have written dozens of books that detail proven methods to help your child sleep through the night, but it's not easy to remember the details of a book you read when it's 4 am and your baby is crying. The Goodnight Sleep Trainer takes these same proven methods and puts them into an easy-to-use electronic device for parents reference. It makes a great gift for new parents. Requires three AA batteries (not included).