As all parents know, the sleeping life of children is exotic and special. Babies usually accumulate a lot of sleep on average 16-18 hours a day in the first fortnight. However, they often wake up and rarely sleep for more than 4 hours in a row, even at night. Their internal clock is not yet synchronized with the 24-hour external day.
It’s an exhausting recipe, but if you understand the science of sleep you can manage and avoid mistakes that will delay the development of your child’s more mature sleep habits.
In this article, you’ll learn about
- fundamental differences between newborn sleep and adult sleep;
- circadian rhythms, and how you can help your baby get in sync with the natural day;
- sleep cycles in the newborn, and how to work around them;
- tips for preventing newborns from waking up; and
- advice for improving your own sleep.
Throughout, I focus on babies under four weeks of age.
Newborn sleep patterns: Are there any?
To a sleepless parent, a newborn's sleep can seem disorganized. Consider these points, for example.
- Newborns never sleep for long.
Newborns sleep for a short time, usually between 30 minutes and 4 hours, at times seen at random during the day and night.
- Newborns awaken easily.
This is partly due to the fact that they spend most of their sleep time in "active sleep", a state of light sleep characterized by the shaking of the eyelids; rapid and irregular breathing; occasional body movements; and vocally (growls or short screams).
- Newborn sleep times can vary widely.
In the early days, the average child sleeps 16-18 hours a day (Iglowstein et al. 2002). Within four weeks, the baby sleeps on average about 14 hours. However, the scope is significant. Some four-week-old babies sleep only 9 times a day, others sleep 19 hours a day (Iglowstein et al. 2002).
If your baby doesn’t fit the typical profile, does that mean something is wrong?
It is not needed. Some babies have health problems that affect how they sleep, so if you are concerned, you should discuss this with your doctor. However, many normal healthy infants appear to deviate from the average sleep duration of several hours.
Newborn sleep rhythms: Why newborns seem to sleep—and wake—around the clock
Circadian rhythms regulate adult sleep times, physiological changes after a 24-hour cycle. Exposure to light affects many of these changes.
For example, when you are exposed to sunlight during the day, you help your body to calibrate its internal clock. Even if you are not sleepy, the morning light will help you to be more alert during the day than at night.
Conversely, the lack of light at night helps the body squirm. When darkness falls, your brain interprets this as a signal that it will start producing melatonin, a hormone that stimulates relaxation and paves the way for sleep.
You can easily interrupt this process by exposing yourself to an artificial evening light source, especially a blue light source (Wahnschaffe et al. 2013). However, if you stick to the schedule - bright light during the day and dark at night - you will likely find yourself in harmony with a natural 24-hour day.
And, of course, most adults are in consultation. However, it is different for newborns.
Newborn sleep is not governed by strong circadian rhythms.
That's not how things start. Not when the kids are still in their bellies. During pregnancy, the fetus is adapted to the mother's physiological features day and night.
When the mother is active, the fetal heart rate and breathing accelerate. When the mother sleeps, they slow down (Mirmiran et al. 2003). These changes can be influenced by maternal hormones, particularly melatonin. Maternal melatonin crosses the placenta and can drive the fetus's internal clock (Torres-Farfan et al. 2006).
However, after birth, this close hormonal connection is broken. Infants must develop their own rhythm of circadian hormone production.
Unfortunately for us it takes time (Kennaway 1996) and the process is complicated because the children have to feed every few hours. As a result, episodes of newborn sleep tend to be short and distributed at relatively regular intervals throughout the day.
So when do babies develop mature circadian rhythms?
It’s normal for babies to take 12 weeks, or even longer.
Most babies take about 12 weeks to show day-night rhythms during melatonin production (Rivkees 2003). Circadian changes in cortisol, a hormone that helps regulate vitality, can take even longer (Rivkees 2003). And in total, it can take 3 to 5 months for babies to "settle down" at night, meaning they sleep more than 5 hours at a time (Jenni et al. 2006; Pinilla and Birch 1993).
Nevertheless, newborn sleep isn’t completely divorced from the natural rhythms of the 24-hour day. Studies show that circadian rhythms begin developing in the first days after birth.
For example, German and Japanese studies have reported that newborns sleep more at night than during the day (Freudigman and Thoman 1998; Korte 2004; Matsuoka et al. 1991).
And scientific evidence suggests that even children accept environmental stimuli. You can use it to shape the sleep mode of newborns.