Newborn infants have distinct active sleep & quiet sleep states present by 27 to 30 weeks gestation. They have more active (or REM) sleep earlier in development. During REM sleep, babies twitch, wiggle around, vocalize, & smile. Also their breathing is irregular & they may hiccup.
Patterns of active & quiet sleep brain activity change in utero & postnatally. When they are born, babies cannot regulate sleep & wake states. That means they “mix up their days & nights.”
The circadian pacemaker located in anterior hypothalamus, is very sensitive to light. However, it is not present in the newborn, & emerges at 5 to 6 weeks after full-term birth. Diurnal sleep is first seen around 12 weeks of age & circadian rhythm is well developed by 4 to 13 months.
Active sleep favors brain maturation & central nervous system development in the newborn. During active sleep there is intense, endogenous, generalized neuronal firing in the brain, retinas, & visual system. Information acquired during wakefulness is processed during quiet sleep. Quiet sleep enables cortical brain plasticity. (That’s a good thing.)
During pregnancy your baby grew accustomed to your movements & daily rhythms during the day. At night, when you were resting, your baby was more active. (Did you notice this?)
You can help your baby adjust to his new days & nights by creating a quiet, dark, & calm evening routine. Swaddling him & using a sound machine at night are other great ways to help him transition. Gentle lullaby music will also soothe your baby.
During the day, keep your baby in a well-lit room (in the middle of daily activities) to encourage frequent awakening & feedings. Noises in your home may arouse your baby from a light sleep state. Time outside in indirect sunlight also helps him to adjust to his new days & nights.
Trying to keep your baby awake during the day, will not make him sleep better at night & may overly stimulate him.
Try not to worry. Your baby will adjust when he is ready.