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 your baby will start to sleep longer. At 6 to 8 weeks of age, most babies begin to sleep for shorter periods during the day and longer periods at night, though most continue to wake up to feed during the night.They also have shorter periods of REM sleep, and longer periods of deep, non-REM sleep.ere are some tips to help your baby settle down to sleep: Set up a sleep schedule. For the first six to eight weeks, most babies aren't able to stay up much longer than two hours at a time. If you wait longer than that to put your baby down, he may be overtired and have trouble falling asleep.