Newborns sleep a lot — typically 14 to 18 hours a day during the first week and 12 to 16 hours a day by the time they're a month old. But most babies don't stay asleep for more than two to four hours at a time, day or night, during the first few weeks of life.
The result? Lots of sleep for your baby and a very irregular — and tiring — schedule for you. Your job is to respond to your newborn's cues, so you'll probably be up several times during the night to change, feed, and comfort him.
This is because, baby sleep cycles are far shorter than those of adults, and babies spend more time in rapid eye movement (REM) sleep, which is thought to be necessary for the extraordinary development happening in their brain. REM sleep is lighter than non-REM sleep, and more easily disrupted.
All this unpredictability is a necessary phase for your baby and it doesn't last long — though it may seem like an eternity when you're sleep-deprived.
At 6 to 8 weeks of age, most babies begin to sleep for shorter periods during the day and longer periods at night, though most continue to wake up to feed during the night. They also have shorter periods of REM sleep, and longer periods of deep, non-REM sleep.
Somewhere between 3 and 6 months, experts say, most babies are capable of sleeping through the night. They're not talking about eight hours, though — they generally mean a stretch of five or six hours.
Some infants sleep for a long stretch at night as early as 6 weeks, but many babies don't reach that milestone until they're 5 or 6 months old and some continue to wake up at night into toddlerhood. You can help your baby get there sooner, if that's your goal, by teaching him good sleep habits from the start.