Newborn babies sleep a lot. They have a lot to learn and need to learn it quickly. It's when they're asleep that their brain organises the great mass of experiences they have accrued when awake. Also, during sleep, chemicals in the brain and the body renew themselves ready for more activity.
However, although babies sleep a lot, they often don't sleep for long. In the early weeks, your baby is likely to have a lot of short sleeps, of differing lengths, which means that they don't really have a 'pattern' as such at all. It's more a matter of little and often and never at the same time, twice! One of the hardest aspects for parents is that new babies wake frequently - perhaps as much as four or five times during the night.
By the time your baby is four weeks old, they may have started to sleep more at night. By three or four months, many babies will have acquired a pattern of being awake during the day and sleeping at night - though some will continue to wake.
Researchers have discovered that at the age of one week, a baby needs, on average, eight hours sleep during the day, and eight-and-a-half at night. By four weeks, they will need six-and-three-quarter hours during the day and eight-and-three-quarters at night.
However, there are wide variations between one baby's need for sleep and another's. Some newborn babies sleep for as much as 21 hours during the day, while others need only eight hours' sleep. In terms of your baby's well being, it doesn't matter where on this range they come, nor does it matter if their sleep is erratic. In the first few months, a healthy baby will take as much sleep as they need, when they need it.