There's nothing like the sight of a peacefully sleeping baby. But as many new parents can tell you, it's a sight they don't see nearly often enough.

No child "sleeps through the night," but babies do reach the point where they get themselves back to sleep when they wake up periodically.

Parents have a lot of questions when it comes to sleep and their baby. The first and most important: How much sleep does my baby need? Here are some general guidelines. (Click here for tips on creating a bedtime routine for your baby or toddler.)

•The amount of sleep needed varies individually with the baby and with the age and circumstances. Some babies are long sleepers and some are catnappers. Some are very regular and others are very irregular.

Click on your baby's age below to learn more about sleep patterns. (And click here to learn about safe sleeping.)

 Newborn

 3 Weeks

 2 Months

 4 Months

 6 Months

 9 Months

 1 Year

 18 Months

 2 Years

 3 Years

4 Years

Newborn

Your newborn baby doesn't know the difference between night and day. She needs to sleep and feed around the clock to grow and develop correctly, so night and day don't matter much to her anyway. In general, your newborn will sleep about 16 to 18 hours out of every 24. A newborn usually sleeps two to four hours at a time and wakes up hungry. She needs to eat around the clock at first but will gradually sleep more at night and less during the day.

You can begin to teach your baby the difference between night and day by behaving differently at different times. During the day, talk to your baby more while you feed her. Keep it light and bright. At night, be more subdued and quiet. Keep the lighting down. Eventually, she'll catch on and begin to sleep more at nighttime.

Tip: When your baby was in the womb, your walking motions lulled her to sleep. It's no surprise that your newborn still loves to be gently rocked and swayed. Swaddling also helps make her feel "at home." Many babies also find comfort in music. But remember: She's supposed to feed every two to three hours around the clock.

3 Weeks

Although your baby still wakes up to eat during the night, he's probably sleeping for longer stretches at a time, maybe for three or four hours. He'll also start to stay awake for longer periods.

Remember, if you're breastfeeding, your hormones have reorganized your sleep patterns to match your baby's. These hormones will help you avoid sleep deprivation if you give yourself a chance. Nap during the day when the baby sleeps. Formula-fed babies may sleep longer because formula tends to stay in their stomachs longer, but in general, their sleep patterns mimic those of their breastfed peers'.

Tip: If your baby tends to sleep all day, dozing through his feedings, try waking him up to eat. He needs to learn that the longest sleeping period is during the night. Help him get a little bit more organized at this point by taking him into the center of family activity at around 4 p.m. Even if he dozes, keep him upright in an infant seat, carrier, or bouncy chair. Then give him a bath around 7 or 8 p.m. This will simultaneously keep him awake and relax him for his long sleep (3 to 4 hours) ahead.

2 Months

Your baby is starting to settle herself down to sleep but probably still needs to wake up to eat during the night. Although her pattern is starting to become more regular, it's also starting to vary. Follow her lead. It's too early for a set schedule, and trying to force one on her wouldn't be healthy.

Babies at this age sleep a little less than they did as newborns, about 15 to 16 hours on average. Your baby will sleep most of these hours at night and will stay awake much longer during the day, although she'll be working her way toward three naps a day. As always, this varies with the baby.

Contrary to what your mother or mother-in-law may tell you, 2-month-old babies don't usually sleep through the night. There are huge differences among babies at this age, but most 2-month-olds still need to eat during the night.

Don't be surprised if your baby starts to be "hyperawake" and crying in the late afternoon or evening. This fussiness is normal. (For more about colic, click here.) When she does settle, she's likely to sleep longer.

Tip: A little whimpering upon waking is normal. Although you should still go to your baby when she cries, give her a little time (five minutes or so) to whimper and cry. She may settle down on her own and go back to sleep.

4 Months

The average 4-month-old baby sleeps about nine to 12 hours each day and takes about three two- to three-hour naps each day. This is a time of gradual transition toward two regular daily naps. On days when your baby has just two naps, he'll probably sleep more during the night.

Most babies this age have put most of their sleep into the nighttime hours and are more awake during the day.

Your baby is now capable of doing a lot more to settle himself to sleep. It's time to set up a pattern of putting him to sleep that will work for him during the night and at naps. Routine is very important to your 4-month-old, so try to make sure things like naps and bedtime happen at pretty much the same time and in the same way every day. You don't have to be rigid, just as consistent as possible.

Tip: Your baby will now roll a bit and will probably move around his crib. Consider a blanket sleeper, or he'll often end up outside of his covers and wake up cold. Check the label to be sure it's flame retardant.

6 Months

Everyone's sleep patterns are different, and the same goes for your 6-month-old. Special circumstances such as sickness or sleeping in a strange bed at Grandma's could affect your baby's pattern; otherwise, her sleeping patterns are settling down.

The average 6-month-old sleeps about 11 hours each night and has settled into two naps of about one to two hours, usually in the morning and afternoon. Almost all healthy 6-month-olds can sleep through the night, with no need for midnight snacks or early-morning conversations unless you want to spend this time with your baby or are trying to keep up your milk supply.

Your baby is starting to get more opinionated, however. This is your last chance to decide where you want her to sleep without her becoming a vocal part of the decision-making process. Developing firm bedtime routines will help her get herself to sleep and stay asleep.

Tip: Here are a few good habits to help make bedtime easier:

9 Months

Sleep concerns are very common at 8 or 9 months. Your baby may wake himself in the middle of the night and then wake everyone else in the household after previously sleeping through the night. This can put a big strain on parents and make them feel that life with their little one is backsliding.

Babies at 9 months sleep about 11 to 12 hours at night. Just as before, your baby will wake up every few hours all night long. The difference now, however, is that he remembers you and misses you when he awakens. Additionally, if he's used to being rocked or cuddled to sleep, then he'll expect the same in the middle of the night. It's up to you to decide whether you're prepared to be a part of this routine or want him to learn to fall back asleep on his own. If he cries, give him a chance to settle back down on his own. If he's frantic, settle him back down as simply and quietly as possible. Try to avoid picking him up if you want him to regularly sleep in his own bed.

Your baby will usually take two naps at this age. Both the afternoon and the morning nap typically last one to two hours. As his parent, you know best how much sleep your baby needs. But no matter what his personal average, he'll sleep less at night if he takes extra-long naps. If this happens in day care, discuss it with the day care provider to adjust your baby's schedule.

Tip: Crawling, climbing, and standing at the crib rail are normal at this age. Be sure your baby's crib is safe, and know that he will learn that he can get down from a standing position on his own.

1 Year

At 1 year, the bedtime struggles begin. Your baby is so excited by her new abilities to move, say words, and feed herself that settling down for bed gets harder and harder. She may tease you and try to get you to come pick her up,— and she's so cute that she's hard to resist! Maintain your bedtime routine, though, as this structure will help you both in the coming months.

The typical 1-year-old will sleep between 10 and 12 hours at night and take a couple of one- to two-hour naps during the day. As always, the amount of sleep depends on the individual baby.

Many children adopt a "lovey," a blanket or stuffed animal, to help them settle. This is a positive step toward independence.

Tip: You may notice that your baby's afternoon nap is getting a little shorter, but that she seems content to play in her crib a bit before calling for you to come get her. Put a few small toys in her crib to encourage this behavior. But make sure they're not too big: She could learn how to stack them and climb out of her crib.

18 Months

Life is so fun and intense for your 1-and-a-half-year-old that going to sleep is the last thing he wants to do. He needs your help to quiet down at night so he can get his much-needed rest.

Babies at 18 months typically need 13 hours of sleep every 24 hours. This is often less sleep than their parents think —(and wish) they needed.

Because sleeping needs are different from child to child, you'll have to figure out what's right for your child. Here are a few suggestions to help you out:

Tip: A bottle at night is a bad habit. It's bad for your toddler's teeth and his ears, and if it becomes part of his routine, he'll always need it to fall asleep, even when he wakes up in the middle of the night. Get rid of it now if you haven't done so already.

2 Years

Your 2-year-old is still trying to bend the rules to be sure they're real, and struggles over getting to sleep are common. She doesn't want to leave you or her exciting day. What to do? Establish rituals and routines for bedtime. It's the best way to encourage good sleeping habits and still make her feel secure.

Different children need different amounts of sleep. But in general, 2-year-olds need 13 hours of sleep per 24 hours. Typically, they'll sleep 11 to 12 hours at night, with maybe one nap each afternoon of one to two hours.

Two-year-olds are big on refusing to go to bed. Being consistent every day about bedtime rules and routines is the best way to teach your child good sleeping habits and make things easier on you. Here are a few tips:

Tip: Leave a book or one other quiet toy in your child's bed so she can amuse herself for a little while after awakening. She can't understand the concept of "too early," but you can tell her to stay in her room until the light comes in the window or she hears you say good morning (or some other specific signal).

3 Years

The average 3-year-old sleeps about 12 hours each day. This usually means 10 or 11 hours at night and a one- to two-hour nap. Naptimes are more variable for 3-year-olds than for 2-year-olds. Your 3-year-old may need more or less sleep depending on the day's events, an illness, changes in his routine, or any developmental changes he's going through. Whatever amount of time your child naturally sleeps in a day is the amount he needs.

Your 3-year-old leads a very busy life, fueled by his improving language ability and active imagination. At night, these can also set the stage for vivid dreams and nightmares. You can't and shouldn't want to prevent his wild dreams; they help him deal with the challenges of his day. But you can help him settle down each night by keeping his bedtime routine calm and simple. Other types of nighttime ups and downs are pretty routine at this age.

Tip: If your child has trouble sleeping without a light on, put a dimmer on the switch and let him adjust it. Praise him as he turns it down, and in a few weeks he'll be used to a very dim light. Or try gradually lowering the wattage of a table lamp bulb over several weeks.

Preschool

Your 4-year-old will have sleep ups and downs: Sometimes she'll be very resistant to go to bed, and other times she'll test your patience by bouncing up again and again, now accompanied by arguments and negotiations.

At this age, most children will give up napping. But if they do nap, that will reduce nighttime sleep, which is about 10 to 12 hours.

If you have to drag your preschooler out of bed in the morning, she may need an earlier bedtime and/or no nap during the day to get in a more balanced schedule. Also avoid altered bedtimes on the weekends. She'll have a hard time adjusting on Monday.

Night awakenings at this age are less frequent, as most preschoolers can get themselves back to sleep. They can remember dreams more than at a younger age, too, so they may recall these upsets in vivid terms. Don't be too worried by the dream content unless your child seems stuck on it.

Tip: Be careful about the types of TV programs (and other types of screen entertainment) your child watches, particularly in the evening. Most children take those images to bed, making it hard to get to sleep or to banish those monsters from under the bed.

Tip: Some medications can disrupt sleep. If there's a new sleep problem and a new medicine, ask your health care provider if they're related.