Sleeplessness is part of having a baby. As many new parents have noticed, newborns spend their first few weeks and months with little concept of night and day. However, babies consistently develop a normal human circadian rhythm, or roughly 24-hour rhythm, within the first few months of life. New research in chronobiology has determined a few factors that help newborns to begin sensing night and day.

Sleep and the Newborn Brain

Our circadian rhythm is a tightly controlled part of our lives. When our retinas sense light, they send cues to the suprachiasmatic nucleus of the hypothalamus, which in turn communicates with the pineal gland. The pineal gland controls the release of melatonin, one of the hormones that sustain our circadian rhythm.

While newborns have a developed pineal gland, one that is actually large for their tiny size, they do not produce enough melatonin, nor do they produce it consistently at night. This leads to the classic well-known newborn sleep cycle, in which they sleep for very short times and at odd hours.

A recent study of the chronobiology of newborns elaborated more on this process of developing a circadian rhythm. The babies studied began to develop daily rhythms in temperature, social behavior, and wakefulness fluctuation early, but sleeping habits were the last to develop. Evening melatonin levels became high enough for the babies to go to sleep at a family bedtime around the 60th day of life.

This is also the time when purple crying and colic usually resolve on their own. Doctors believe that melatonin may be responsible for the end of nighttime wailing as well as the beginning of more parent-friendly sleep habits.

Breast Milk and Melatonin

However, there is hope for parents who are struggling through the first 60 days and the odd schedule that this time brings. While infants do not make enough melatonin to go to sleep at night on their own, they have another source: breast milk. Melatonin from the mother is present in her milk. This may help breastfed babies to sleep more soundly and also reduce the hours of walking an inconsolable newborn. Some doctors and researchers in circadian biology are even suggesting that supplementing melatonin in these early weeks can prevent colic while helping the infant to transition more quickly to a mature circadian rhythm. However, this issue is still being researched and no parent should give their baby any supplements without a doctor’s approval.

Circadian Rhythm in Infants: Hope for New Parents

Until infant supplementation of melatonin has been thoroughly studied for safety, there is light at the end of the tunnel for new parents who long for a good night of sleep. There are ways to help infants develop a circadian rhythm as quickly as possible. First, turning down the lights at bedtime, including televisions and other screens, will encourage newborns to begin sensing night as a time to sleep. Similarly, reducing ambient noise and social interaction can help to encourage the idea that night is a time for sleep and not play. It takes two to three months for the infant brain to develop the ability to produce melatonin in levels needed for sleep, but these environmental and social cues will help.

It is important for all people, including babies and their parents, to have a healthy circadian rhythm. While newborns appear to take time to develop their internal 24-hour clocks, parents can encourage them to sleep at night by breastfeeding and by changing the environment to one that supports nighttime sleeping.