Heart rate variability, or HRV, is a metric often computed by a biofeedback machine to determine the regularity of a heartbeat. It compares the time between each beat, to determine how steady your heart performs.
1 When your baby is getting sleepy, put your baby in his or her crib in a quiet, darkened room. 2  This will help your baby learn to go to sleep in his or her crib. 3  Don't rock your baby to sleep after about age 4 to 6 months. 4  Rock your baby, but lay the baby down to sleep while he or she is drowsy but still awake. Give your baby a bath, sing lullabies, read a book, or tell a story. 2  These activities can help your baby relax. 3  They also signal that it is time to sleep. 4  Don't get your baby excited with active play right before sleep. 5  When your baby is getting sleepy, put your baby in his or her crib in a quiet, darkened room.
When is it safe to let my baby sleep on his tummy? To reduce the risk of sudden infant death syndrome (SIDS), experts recommend that you place your baby on his back when you put him down to sleep during his first year. The risk of SIDS peaks between 1 and 4 months of age but remains a threat until babies are 12 months. Once your baby is strong enough to roll from back to front and front to back by himself, you don't need to worry about him rolling onto his stomach during sleep.