Newborns sleep quite a lot in the early weeks after birth. On
average, a newborn baby requires about 16-17 total hours of sleep, but this
amount tends to come in short bouts, i.e., it is frequently interrupted, mainly
for the need to feed every 2-4 hours. Also, most newborns sleep for an hour or
two at a time (and sometimes even less than that).

Newborns sleep in bits, typically ranging from 30 minutes to 4
hours, and in a disorganized fashion (at random times) throughout the day and
night. Newborn sleep is also easily interrupted: they awaken easily. This is
because a large portion of their sleep time is spent in “active sleep,” a light
sleep state characterized by fluttering eyelids; rapid, irregular breathing;
occasional body movements; and vocalizations (grunts or brief cries).

It is worth noting that
newborns vary greatly in the total amount of time they spend sleeping. In the
first few days, the average newborn sleeps between 16-18 hours a day. By the time they
become 4-6 weeks of age, babies will need more like 14-16 hours of sleep each
day. Some four-week-old babies sleep as little as 9 out of 24 hours. Others
sleep for 19 hours a day. By 8 weeks of age, some, but not all, babies will start to sleep
for shorter periods during the day and slightly longer periods at night. But be
aware that babies will still wake multiple times each night for feedings.

The timing of adult sleep is governed by circadian
rhythms--physiological changes that follow a 24-hour cycle. Many of these
changes are influenced by your exposure to light.

When
you expose yourself to sunlight each morning, you help maintain your internal
clock. Unfortunately, newborn sleep is not governed by strong circadian
rhythms.

During
pregnancy, fetuses are tuned into their mothers’ physiological cues about day
and night. Fetal heart and respiratory rates increase or decrease in response
to the mother’s physical activity. Such changes may be influenced by maternal
hormones, particularly melatonin, which can be passed to the baby through the
placenta and may direct the fetus’ internal clock.

After
birth, the newborn baby must rely on his/her own internal clock, which is not
yet fully developed. Instead, the axis around which the life of the newborn
revolves is the feeding: the sleep patterns newborns are shaped by the length
of time it takes them to feed, digest, and become hungry again.

For
most newborns, this means feeding every few hours. Sleep episodes are brief and
spaced in fairly regular intervals around the clock.