Sleep is a physiological need of primary importance to a baby's health. Sleep allows good physical and cerebral development. Sleep rhythms are established very gradually during the first months of life. Babies have a very different sleep pattern than adults.

Here are the different characteristics of infant sleep. Recognizing them will help you use simple and comforting gestures to put your baby to sleep. 

Between 0 and 3 months

A newborn will sleep, on average, 17 to 20 hours a day in very short 50-minute cycles. Sometimes 2 to 3 cycles follow each other, and the baby sleeps for 3-4 hours. The frequency of waking will depend mainly on the baby's primary feeding needs. The baby does not yet have a circadian rhythm, the 24-hour biological rhythm is not yet integrated with their system, and they cannot yet distinguish between day and night.

The sleep of the infant is made up of 2 phases which constitute a cycle:

- A phase of restless sleep: the baby moves its limbs; it is noisy, and its breathing is irregular. They make soft sounds. Small movements animate the child's face, and they can even open their eyes at times.

- A calm sleep phase: the baby does not move, its face is relaxed, the muscles are slack, and breathing is calm. Only a few sucking movements can be observed.

During the first weeks of life, the internal clock and the sleep structure are gradually put in place according to neurological maturation and the quality of the environment. Each baby has its own sleep needs. From the first weeks, babies can be "heavy sleepers" or "light sleepers."

Up to 3 months of age

The baby learns to distinguish between day and night: the circadian rhythm will gradually take hold. The baby will be more awake at the end of the evening, associated with agitation and irrepressible crying. 

Between 3 and 6 months

Between 3 and 4 months, calm sleep is structured in 2 sleep phases:

- Slow/light sleep: the baby relaxes but still hears outside noises.

- Slow/deep sleep: the baby no longer hears anything. They are in a deep sleep. 

The baby's internal biological clock, which regulates waking and sleeping periods, is now adjusted. The need for sleep is gradually reduced (between 14 and 15 hours per day), and most babies start to "sleep through the night," i.e., they sleep for 5 to 6 hours at a time. However, about 15% of children still do not sleep through the night after 6 months. In this case, you should not hesitate to talk to your pediatrician. 

Between 6 and 12 months

After 6 months, babies sleep on average 8 to 12 hours per night. From 7 to 11 months, the child experiences separation anxiety, a normal stage in their development, which causes them difficulties falling asleep. During these few months, before gradually learning to go back to sleep independently, they will need to be reassured by their parents' voices or cuddles.