Babies’ sleep patterns can feel as mysterious as the Bermuda Triangle, and as hard to get through. But like the Bermuda Triangle, in real life, most people do come out the other side just fine. When it comes to those early childhood sleep patterns, as unpredictable as they can start out, sooner or later, babies develop the same rhythms that tell the rest of us when it’s time to get some sleep, and, usually, when we need to wake up again. This is called the circadian rhythm, from the Latin meaning “around the day,” and can be thought of as the body’s internal clock.
Some of the earliest building blocks of this more regular sleep schedule – REM and non-REM sleep – develop when Baby is still in the womb, in the last few weeks of gestation. Others, though, like the production of the hormone melatonin during the night to help Baby sleep, won’t start kicking into gear until somewhere near their third month.
Babies don’t develop this part of their sleep rhythms in the womb because they’re still piggybacking off of mom’s, and breastfed babies can continue to do so for a while longer. Breast milk produced at night has melatonin in it, and can help make babies sleepier, which is why breastfed babies can start developing circadian rhythms a little earlier than other babies, especially if they don’t drink expressed milk from bottles at night.
How can I help?
Circadian rhythms tend to show up and start helping Baby fall into more regular sleep patterns sometime between 2 and 4 months, but there are some things you can do to help them get there faster. The fact that circadian rhythms develop at around the same amount of time after birth in preemies as they do in babies who were carried to full-term suggests that developing them has more to do with how Baby experiences the world after birth than it does with their development. You can encourage them to develop them by making sure they get some sun and natural light during the day, and that their room stays fairly dark at night, even when they wake up for feedings. Having a general routine for Baby’s day, including bedtime, could help, too. Some researchers believe social cues are one of the most important factors in establishing circadian rhythms.