SURELY they could spare a little milk, right? But when John and Mary Rose Lin of Jersey City ran out of milk for their 18-month-old twins on a recent Continental flight from Newark to Maui, the flight attendant refused to give them more. That particular beverage, the Lins recall being told, was for coffee, not children. “I was not asking for a full bottle, just a cup,” said Mrs. Lin, noting that she even offered to pay for the milk.

It was the low point of an otherwise arduous trip. Her children are active, and efforts to allow them to move around the cabin were not welcomed by the plane’s staff. They were told to head back to their seats when they lingered near the rear galley; letting the children stretch their legs in the aisle was also not an option. “Not a lot of people sympathize with your situation,” said Mrs. Lin of the 12-hour ordeal. “If you feel like someone is going to help you, chances are no one will.”

The misery of air travel is no surprise to anyone who has boarded a domestic flight in the last five years. As airlines have maximized capacity and slashed services, passengers have learned to brace themselves for packed planes, stuffed overhead bins, harried flight attendants and fees for everything from pretzels to pillows. On top of that, delays and cancellations are up.

For families, however, the costs and the inconveniences are compounded. At a time when resorts, cruise lines and tour operators are courting junior guests as if they were celebrity V.I.P.’s, flying with children has become an increasingly costly, “Survivor”-like ordeal. Baggage fees? Start multiplying. Early boarding? Probably not. Hoping to sit together? Don’t count on it (unless you’ve paid extra). A few empty seats where a child can spread out and nap? Good luck with that!

It wasn’t always like this, of course. In the golden age of flying in the 1960s and ’70s — the one now being so lovingly burnished by ABC’s “Pan Am” — families could expect to be the first ones on the plane. They would then be greeted by smiling flight attendants bearing miniature pilot wings for children who would be treated to a tour of the cockpit before settling into their seats. And even as recently as a few years ago, families could count on a handful of common courtesies, like boarding before other passengers, landing a roomier seat in the first row of coach, bringing certain strollers onboard, and even being able to get milk on board.

“We used to carry five to six cartons of milk on each flight for coach,” said Elaine Sweeney, 58, a flight attendant with American for more than 30 years. But that was five or so years ago. Now, she said, after 9 a.m. there is no milk in coach on her flights — just two pint-size cartons in first class, where cookies are served. “So do we give it to a child in coach or a first-class passenger that has paid full fare?” she asked. “Quite the conundrum.” (American, by the way, says it stocks food and beverages based on individual markets.)

To traveling families, the erosion of such niceties is just an indirect way of suggesting that they take the bus.

Not so, counter the airlines; it’s a matter of resources. American carriers have lost about $55 billion over the course of the past decade, according to the Air Transport Association, as operational costs, like fuel and employee benefits, have outpaced revenues. Making up for those losses has meant cutting benefits and adding fees for everyone. (This year, most domestic airlines are on track to post their fourth year of modest profits since 2000.)

And while we may miss the golden days of air travel, flights cost less now than they did then. Adjusting for inflation, the average round-trip domestic fare in 1979 was $559.31; last year it was $316.31. For families, in particular, that is a meaningful difference. More than anything else, said Michael Boyd, president of the Boyd Group International, an aviation consultancy, “families generally travel based on price.”

Given the current economic climate and families’ desire for cheap flights, Mr. Boyd doesn’t expect things to improve soon. At best, he said, airlines “treat families like everybody else.”

“If you get a good flight attendant they might help you warm the bottle,” he continued. “Other than that you’re on your own.”

So for anyone planning to brave the indifferent skies with children this season, here are a few of the major sticking points and tips on how to navigate them.

Why Is Everyone Else Boarding First?

As recent as four years ago, some airlines were still routinely calling families to board first. The idea was that getting children on early was not just a courtesy for families — who got extra time to settle in — but a benefit that improved boarding for everyone. The policy has been declining over several years, and now, with early boarding a privilege people can pay for, it is rare to find someone who has been invited to board first as part of a family. (Airline representatives all say that they allow families to board if not first then at least before coach passengers paying regular fare, but anecdotal reporting suggests otherwise.)

WHAT FAMILIES CAN DO

The only way to guarantee early boarding for your family is to buy it. Check with the airline to see what they offer. Short of that, explain to the gate agents why you would like to board early and see if they can help. If necessary, refer to their early-boarding policies (see accompanying article) for backup. Or give up any hope of using your overhead bin and board last with the idea of keeping restlessness to a minimum.

My Kids Are Seated Five Rows Behind Me!

Planes are flying mostly full most of the time thanks to major capacity cuts over the past decade; during peak travel times, empty seats are even harder to come by. For families, this means that it is increasingly difficult to get seats together, a particular gripe for those who, like Sierra Black, have found themselves jockeying for seats onboard.

Last February, US Airways placed Ms. Black and her two children, ages 5 and 2, in the center seats of three different rows in different parts of the plane for a five-hour flight to Tucson — an experience Ms. Black chronicled in a series on her blog, ChildWild. After a flight attendant insisted that the family take their assigned seats — which caused the children to cry, since they were separated from their mother and sitting between strangers — Ms. Black ultimately managed to commandeer seats for the three of them together, but only after the entire plane had boarded.

“Even if I wanted to leave my 2-yr-old in row 26 while I kicked back with a paperback up in row 5, I kind of think I shouldn’t be allowed to,” Ms. Black wrote on her blog. “Doesn’t the airline have a responsibility, for the safety of all its passengers, to keep young kids with their caregivers?”

Responding, Todd Lehmacher, a US Airways spokesman, wrote in an e-mail, “We are sympathetic to families traveling together and make every effort to accommodate their request.” But, he added, “We also have to weigh the needs of our other customers.”

When flights were less full, flight attendants say, reseating passengers so that family members could sit together wasn’t a problem. Now, if any open seats are left at all, they are usually the middle ones, making it difficult to persuade other passengers to swap seats — a task flight attendants are not required to do.

WHAT FAMILIES CAN DO 

First, book as early as possible so more seats are available. If you cannot find seats together, call the airline and ask an agent to make a note on your reservation indicating which family members are minors, recommends Henry H. Harteveldt, a travel industry analyst and co-founder of Atmosphere Research Group, based in San Francisco. “If for some reason the airline changes planes or the seating configuration changes,” he said, “families usually get priority.”

If nothing comes of that, check back with the airline one to three days before departure, when seats for customers with disabilities are often released. If those seats are not taken, they are released to other passengers.

And, of course, you can throw money at the problem. Most airlines now put a price tag on the most desirable seats, which may remain available when the rest of coach is sold.

“It’s almost like you’re forced into it,” said Carla Caccavale Reynolds, a public relations executive from New York and mother of four, who paid $70 extra a head for herself, her husband and three of her children to sit together on a packed JetBlue flight from New York to Aruba for at total of $350 on top of the tickets. (The 8-month-old traveled on her lap.) “The only seats available were the ones that cost extra,” she said. But faced with the prospect of sitting apart, “I said, ‘Fine, just do it,’ ” she said.

‘If You Don’t Bring It, We Don’t Have It’

No one should be surprised by having to take food onboard (or pay for it), in addition to basic supplies, but some families, like the Lins, who were refused milk for their twins, are startled to discover just what isn’t available.

Mary Clark, a spokeswoman for Continental, the airline the Lins were flying, said that the family’s experience wasn’t typical, and that the airline offers a “variety of complimentary beverages on all of our flights, but occasionally a specific selection may not be available due to customer demand.”

Families aren’t the only ones affected by the new austerity. Flight attendants, too, miss the days when they could give people pretty much what they needed. “I remember the days when we had lemonade in the summer, hot chocolate in the winter,” said Beth Donnelly, a veteran flight attendant with American Airlines who began her career in 1977 on Braniff International Airways. “We had the wings and coloring books, baby food and diapers. Families would come on first and get settled in.”

Now, she said, “it’s hurry, hurry, hurry. Poor people. Now, if you don’t bring it, we don’t have it.”

WHAT SHOULD FAMILIES EXPECT AND DO?

Even when airlines offer food onboard, often the thing you want is sold out. To ensure that your family has what it needs, bring it yourself.

Keep in mind that baby formula and food, breast milk and juice are allowed “in reasonable quantities” exceeding the usual 3.4-ounce security limit, according to the Transportation Security Administration.

Consider buying perishables like milk after clearing security and asking a flight attendant to put those items on ice. Or bring something like Parmalat or Horizon Organic’s eight-ounce low-fat milk boxes, which can be stored at room temperature until opened. For more tips on foods that travel well, see the June 22 Practical Traveler column, “Pack a Picnic for Your Next Flight.”

Does It Have to Be This Way ?

For Americans used to domestic flights, the first taste of a foreign airline can be a head-turner. Eric Lorge, a media studies professor who regularly visits Los Angeles from Europe, was flying American before he tried Air Tahiti Nui from Los Angeles to Paris with his wife and three children, all under the age of 5. He liked that they would often get priority boarding as a family, but what won him over was the way the flight attendants handled his daughter when she was sick. “They kept bringing warm washcloths and water and asking if we needed anything.” His experience with United States carriers? “I try to avoid them if at all possible.”

Not all foreign airlines roll out the red carpet for families. In 2004, Malaysia Airlines banned children under the age of 2 from traveling in first-class sections on its Boeing 747 jets. Next year, when it is expected to get the first of its Airbus A380 superjumbo jets, the airline will extend the ban to them as well. But the services offered to families by most foreign carriers, which include baby sitters in waiting areas and automatic 25 percent discounts (see accompanying article), far exceed those offered by American counterparts.

To be sure, a handful of family courtesies remain on domestic flights, including checking a stroller and car seat at no charge. Children under the age of 2 can fly free on a parent’s lap within the United States.  And most airlines will allow children to sit in an approved car seat if there is the space for it onboard. On overseas flights American carriers tend to offer families more amenities — bassinets for infants, pillows, blankets and the occasional child’s meal — because they are competing with foreign airlines.

But why can’t all flights within the United States strive for those foreign flourishes?

“It comes down to one thing, and one thing only: cost,” said Mr. Harteveldt, of the Atmosphere Research Group. “With travelers so focused on saving money, airlines simply can’t afford to offer the amenities foreign flag airlines offer. In addition, U.S. airlines have higher labor costs than many foreign-flag airlines, leaving them with less margin to offer kid-friendly amenities.”

Some travel experts believe that airlines are missing an opportunity by not catering to families. Joanne Gardner, owner of the Travel Specialist travel agency in Wheaton, Ill., said nearly half of her business was planning family vacation. She estimates that 25 percent to 35 percent of her clients actively avoid flying. “People really dislike the whole experience,” she said, from the baggage fees to having to bring on their own food. “Clients are preferring to take trains, rent a car or drive on their own.”

So far, this doesn’t seem to have the airlines worried. Only a few airlines track the number of families flying with children. Those that do say they haven’t noticed any change. “There’s plenty more passengers where you came from,” said Mr. Boyd, the Colorado aviation consultant, summarizing the airlines’ stance: “We don’t have to fight over it right now.”

But at least one person would like a reason to get on a plane again. Two and a half years ago, Kari Dilloo, communications manager for Bing Travel, the Microsoft search site, took her twins, then 3 months old, on a 90-minute flight from Seattle to Salt Lake City. Nothing terribly bad happened, but there was so little support from the airline and other passengers that they’ve opted for road trips ever since.

“I already had low expectations,” said Mrs. Dilloo, who had spent months planning the trip and asking friends for tips. “But they dropped even more.” If there was an airline that catered specifically to families, she added, “we’d fly them.”

Is Your Airline Child-Friendly?

Like all coach passengers, families are increasingly forced to pay up if they want any onboard perks. Here’s a look at what families can expect from a range of American carriers on domestic flights.

American

EARLY BOARDING No. Families who want to board earlier can ask the gate agent or pay $10 a person to guarantee a spot in the first boarding group in coach.

SEATING Bulkhead seats toward the front of coach are reserved for elite passengers or sold as “preferred seats” 24 hours before departure for a fee starting at $4.

KIDS’ MEALS Sells a number of “kid-friendly choices” like $10 turkey sandwiches with chips.

ENTERTAINMENT Free child-friendly movies on overhead televisions on most flights longer than four hours. Streaming video via Wi-Fi will be added to 85 MD-80 aircraft before the end of 2011.

STROLLER GATE CHECK Yes, except noncollapsible strollers or those weighing 20 pounds or more, which must be checked at the ticket counter.

Delta

EARLY BOARDING Yes (no age limit), ahead of first and business class.

SEATING Bulkhead seats may be available for families 24 hours before departure.

KIDS’ MEALS $4.50 kids’ peanut butter and jelly plate, served with fruit and vegetables.

ENTERTAINMENT Last year, Delta brought back the kiddie pilot wings it used to hand out. On flights with seatback televisions, Delta offers 16 On Demand children’s television programs that cost $1 per episode or $6 for a television bundle. (Flights without seatback screens may not offer children’s movies at all.) Some flights have Nickelodeon and Cartoon Network via satellite television (at no charge).

STROLLER GATE CHECK Yes.

JetBlue

EARLY BOARDING Yes, for families with children under the age of 2, along with passengers who paid extra for seats with more legroom.

SEATING Bulkhead seats are reserved for customers with disabilities up to 24 hours before departure, with remaining seats sold as “Even More Space” seats for $10 to $65 extra.

KIDS’ MEALS JetBlue doesn’t offer meals on any of its flights, but snacks, including Animal Crackers, are free.

ENTERTAINMENT Seatback televisions offer 36 channels of DirecTV, including children’s programming and 100 XM Satellite Radio channels free. If time permits, pilots are encouraged to show children the flight deck and offer them JetBlue trading cards.

STROLLER GATE CHECK Yes.

Southwest

EARLY BOARDING Yes, for families with children up to 4 years old, after passengers in boarding Group A, which includes elite fliers, full-fare passengers and those who pay $10 (each way) for early-bird check-in.

SEATING There are no seat assignments. Like other passengers, families must find an open seat once onboard.

KIDS’ MEALS No meals onboard. Peanuts and pretzels are free.

ENTERTAINMENT Flight attendants are encouraged to offer children coloring books and airline wings.

STROLLER GATE CHECK Yes.

United-Continental

EARLY BOARDING Yes, for families with children 4 years and younger, after passengers who paid extra for priority boarding on United, which merged with Continental last fall. Continental currently does not sell priority boarding; families board after first class and elite passengers.

SEATING Bulkhead seats are typically reserved for elite passengers or sold for a fee starting at $9.

KIDS’ MEALS Snacks and meals, including $7.49 cheese and fruit plates, are offered, depending on length of flight and time of day.

ENTERTAINMENT Most of United’s fleet has overhead screens that show in-flight movies. Continental offers satellite TV on more than 75 percent of its 737 Next Generation aircraft and plans to install the service on more planes in 2012.

STROLLER GATE CHECK Yes, except large, noncollapsible strollers, which must be checked at the ticket counter.

US Airways

EARLY BOARDING Yes, for families with children 4 and younger, along with elite passengers and those who paid extra for bulkhead seats.

SEATING Bulkhead seats are reserved for passengers with disabilities until an hour before departure and are assigned at the gate agent’s discretion.

KIDS MEALS Snack boxes, which include dried cranberries and almonds ($6), and meals including fruit and cheese plates ($8), depending on the length of the flight and time of day.

ENTERTAINMENT Nothing on domestic flights.

STROLLER GATE CHECK Yes, except for noncollapsible strollers, which must be checked at the ticket counter.

Virgin America

EARLY BOARDING Yes, for families with “small children,” after first class and passengers who paid extra for roomier coach seats.

SEATING Bulkhead seats are reserved for “main cabin select” passengers who pay more when booking or $39 to $129 extra to upgrade 24 hours in advance.

KIDS’ MEALS Half-sandwiches like peanut butter and jelly served with organic fruit gummy bears ($4).

ENTERTAINMENT Individual seatback screens offer parental controls, free satellite TV including the Disney Channel and Nickelodeon, movies ($5 to $8) and premium programs like “Go Diego Go” ($2 to $7), free video games and seat-to-seat chat.

STROLLER GATE CHECK Yes.

Discounts, Diapers and Birthday Cakes: Life on Foreign Carriers

International routes generally tend to have more child-friendly perks, like children’s meals and bassinets, but some airlines go above and beyond the basics, providing things like child-size headsets and children’s meals that are served before adults’. Here’s a look at what lengths some foreign carriers go to for families on international flights.

Air New Zealand

Activity packs that feature “Jet Cadet” cartoon characters are available for children ages 3 to 11 on long-haul flights, as are limited quantities of disposable diapers, drinking cups and formula. Children’s meals include scrambled eggs, fruit salad and cereal for breakfast and spaghetti and meatballs for dinner. And its SkyCouch, a trio of economy-class seats that can be turned into one large, sofalike bench by tucking the armrests back and lifting the leg rests, offers families more flexibility. Costs: $100 to $150 on top of ticket prices for a family of three from Los Angeles to London or Auckland.

Air France

Kids’ meals, including pre-sliced meat and fish for easy eating, cookies and jars of baby food are available on flights of two and a half hours or more if ordered in advance. For children between 2 and 11, discounts of 33 percent are offered on some long-haul flights. Finger puppets, colored pencils and activity books are also offered onboard.

Air Transat

This Canadian charter company was the winner of the Family Friendly Airline Award, presented by the Kids First Fund earlier this year. It offers dedicated family airport counters at Canadian gateways, courtesy strollers in Montreal, Toronto and Vancouver, and Air Transat Kids Club for 2- to 11-year-olds who live in Canada. Kids Club members receive priority bag handling, free seat selections (normally between 15 to 70 Canadian dollars, about the same in United States dollars, depending on seat and route), a surprise from the crew when flying on their birthday, and entry into two yearly drawings for family vacations to Walt Disney World or Paris. All children traveling from Canada to Florida receive an activity book featuring the airline’s mascot, AirNest.

British Airways

In addition to specially designed “carrycots” and infant seats for children up to 2 years old, the airline supplies Skyflyer activity packs for children under 12 on all flights over three hours long. The “feed kids first” policy is designed to ensure that parents can eat in peace. One thumbs down: The carrier began charging £25 (about $40) for seat assignments in coach two years , roughly $160 extra for a family of four. Families who don’t pay for seat assignments will get seats three days before departure. “If the group cannot be seated together, each child will be seated with an adult at least,” according to the airline Web site.

Cathay Pacific

Children 3 to 6 years old are referred to as Junior V.I.P.’s and offered packs with activity books and games. Diapers and Mustela diaper cream are offered to parents with infants. Children’s meals are served with colorful cutlery.

Emirates Airlines

Children 12 and under receive backpacks with a children’s magazine, puzzles, games, coloring pencils, a child-size sleeping mask and a stuffed animal. Jarred baby food and children’s menus with items like macaroni and cheese, chicken nuggets, pasta and veggie burgers are available on every flight, and the bulkhead row at the front of coach, where bassinets are located, is reserved exclusively for passengers traveling with infants. Children receive kid-size headsets to use with the seatback television screens offering 27 children’s channels, 36 Disney classic movies, and other movies for youngsters each month. Birthdays are marked with a special cake and Polaroid picture if the airline is notified in advance.

Etihad Airways

First- and business-class lounges in Abu Dhabi are staffed with nannies in dedicated family rooms. Onboard, children receive a kids’ pack with activity books and stickers and can choose from several video games, eight child-friendly movies or a children’s channel.

Lufthansa

Its child-vetted children’s menu includes animal-shaped entrees. Themed onboard souvenirs are periodically offered to children (this month it was a Halloween flashlight). And English-speaking airport guides can be hired through the Lufthansa Family Service at its hubs in Frankfurt or Munich for a fee of 55 euros (about $76) for a family of five.

Virgin Atlantic

Children receive backpacks with coloring books, toys, sunglasses, hats and other surprises. Children’s meals, which must be reserved in advance, include chicken fingers and pizza served with child-size cutlery and a side of a fruit, vegetable, yogurt or string cheese. Children 2 to 12 pay 75 percent of the adult fares. Bulkhead seats are specifically reserved for parents with infants, and specially designed infant cots and chairs are available for children up to 3 years old. A limited supply of diapers, bottles and baby food are also offered onboard.

The Hip Pocket is great, it holds quite a bit while staying attached and not getting in the way at all. You can definitely fit a diaper and a few wipes in there, and probably a few more little wallet items besides. Maybe even sunglasses.

If you need to carry more than that, like a bottle of water, change of clothing, snacks, etc., then definitely check out the new Boba Pack Travel Bag…it fits onto the outside of the Boba G3 very nicely and holds a lot of necessities without being bulky at all. You can also use it as a messenger bag…the new G3 has a strap holder that will keep it attached and won’t let it fall off your shoulder. Ergonomically though, it’s best to attach it to the outside of the carrier and keep the weight centered on your body, not over to one side.

Warmly,
Laura Hamilton
http://www.theportablebaby.com

What makes a child nap? Most parents cherish toddlers’ naps as moments of respite and recharging, for parent and child alike; we are all familiar with the increased crankiness that comes when a nap is unduly delayed or evaded. But napping behavior has been somewhat taken for granted, even by sleep scientists, and napping problems have often been treated by pediatricians as parents’ “limit-setting” problems.

Now, researchers are learning that it is not so simple: napping in children actually is a complex behavior, a mix of individual biology, including neurologic and hormonal development, cultural expectations and family dynamics.

What parents usually want to know is simply how long a child should nap. That concern dates back a little over a hundred years: In the first decade of the 20th century, European experts published the original studies measuring the sleep patterns of children and promptly began worrying they were not getting enough sleep.

Today, researchers believe that very young children take naps because so-called sleep pressure builds rapidly in their brains — that is, the need for sleep accumulates so quickly during waking hours that a nap becomes a biological necessity. It is not just a question of how much total sleep that children need in 24 hours. Possibly because of the intense synaptic activity that goes on in their highly active, highly connected brains, young children are less able to tolerate long periods of time awake.

In the early 1980s, Dr. Alexander A. Borbély, a professor of pharmacology at the University of Zurich, Switzerland, posited a “two-process model of sleep regulation.”

The “circadian process,” which has been localized to a specific place in the brain, works a little like a clock, tying our sleep to schedules and to cycles of light and dark, regardless of how much we have or have not slept. This interacts with the “homeostatic process” which works differently, pushing us harder toward sleep the longer we stay awake and building up sleep pressure, which can be measured via EEG recordings.

Napping happens “because children have a much faster sleep homeostasis — they build up sleep pressure more quickly, they are not so tolerant toward longer waking periods,” said Dr. Oskar Jenni, a pediatrician who is director of the child development project at the University Children’s Hospital Zurich.

Generally, new infants sleep between feedings in short periods both days and nights. As they grow, babies sleep at night (more or less), waking to be active in the early morning and taking morning naps; they wake again for play and food, followed by afternoon naps.

Sometime after the first birthday, the two naps are consolidated into one, usually in the late morning or early afternoon. “The rationale for having your afternoon nap over by 3 p.m. is to build up enough sleep drive so you can fall asleep at night,” said Dr. Judith Owens, a pediatrician who is director of sleep medicine at Children’s National Medical Center in Washington.

As they grow toward school age, most children begin to fight against that remaining nap or just leave it behind. But there is a great deal of individual variation, and many parents struggle with a child who seems too eager to do without a nap.

Sometimes problems arise because relinquishing the nap conflicts with a parent’s daily program or a day care center’s routine. Sometimes the parent sees the tantrums and whining and general negativity that come with fatigue, a sign that the child is not really ready to do without a nap.

“By age 5, about 80 percent of kids have given up a nap — that means one in five still napping,” Dr. Owens said.

Dr. Jenni was one of the authors of a large study, published in 2003 in the journal Pediatrics, which measured sleep duration across childhood. He and his colleagues documented the decrease in daytime napping and the consolidation of nighttime sleep as a group of Swiss children grew up. They also found that individual children’s sleep needs and sleep patterns tended to be consistent through age 10. In other words, children who slept less than their peers as infants grew into older children who seemed to need less sleep.

A 2005 study of American children ages 3 to 8 showed distinct differences between black and white children, too. While total sleep duration for the two groups was similar, black children napped more and tended to be older when they gave up their naps.

Despite the intriguing findings, the study of napping patterns is still in its infancy — or perhaps toddlerhood. Experts are just beginning to understand the biological underpinnings.

Dr. Monique LeBourgeois, a sleep scientist at the University of Colorado at Boulder, and her colleagues recently conducted the first study on how napping affects the cortisol awakening response, a burst of hormone secretion known to take place shortly after morning awakening. They showed that children produce this response after short naps in the morning and afternoon, though not in the evening, and it may be adaptive in helping children respond to the stresses of the day.

By experimentally restricting sleep in young children, and then analyzing their behavior in putting puzzles together, Dr. LeBourgeois’ group also is quantifying how napping — or the lack of it — affects the ways that children respond to situations. “Sleepy children are not able to cope with day-to-day challenges in their worlds,” she said. When children skip even a single nap, “We get less positivity, more negativity and decreased cognitive engagement.”

But for parents and scientists alike, there are many unanswered questions: When is it too early to give up a nap? Too late to hold on to a nap? How do domestic patterns and cultural norms affect the circadian and homeostatic processes?

“I think there’s a dire need for adults in general to be in tune with individual children’s physiology,” Dr. LeBourgeois said. “What are the capabilities, and what are the limits?”

This everyday childhood behavior, commonly a source of family struggle, is the product of cultural and familial expectations as well as complicated biology, which changes as the child grows.

“If the child is stopping the napping, that represents a process of neurological maturation,” Dr. Jenni said. “The ability to tolerate wakefulness is an indication that the brain is maturing.”