As another reviewer stated, these are absolutely not safe for sleep. I see many parents gushing over how wonderful these things are, but so many fail to realize that many of the products marketed for babies and especially to new parents are unsafe and are oft times directly against CDC and AAP recommendations. Follow the recommendations - they exist for very good reason. If you do choose to use these, my advice would be never to use them for sleeping, never leave your child unattended in it, and do not use them excessively: be warned that they are also huge (well-documented) culprits for malformation of the skull when used excessively and for prolonged periods, often resulting in babies needing correction of their head shape and development via medical helmets that often must be worn for several months. You are your best advocate and your child's only advocate - RESEARCH all of the products you have for your child and change your practices if you discover that you've been making errors. It happens to the best of us. Be safe!