It's a precious moment for families around the world when twilight falls, children yawn and bedtime routines engage.
Yet the places where children sleep, the time they lay down at night and even how they prepare for shut-eye vary across cultures.
Even differences in children's bedrooms around the world can be striking, as in Venice-based photographer James Mollison's photo series "Where Children Sleep," which has been adapted into a book.
Though it has been nearly seven years since the series was published, the photographs still spark conversation as they turn a lens to bedtime around the globe.
While photographing the series, "I met many families who sleep together in one room or children who sleep in a space of convenience, rather than a place they can in any sense call their room," Mollison said.
"I came to appreciate just how privileged I was to have had my own bedroom to sleep in and grow," he said. "I met children who had literally nothing except for a place to sleep and other children who couldn't move for all their toys."
Here is a sampling of what bedtime looks like in households around the world.
Drastic differences in babies' bedtimes
While researching children's sleep across the globe, clinical psychologist Jodi Mindell was surprised to discover significant differences in bedtimes for infants and toddlers based on where they lived.
She described the differences as "unbelievable."
"When I walked into doing this study, I really thought we would see 10- or 15-minute differences," said Mindell, a professor at Saint Joseph's University in Philadelphia and associate director of the Sleep Center at Children's Hospital of Philadelphia.
It turned out, however, "we're seeing these 2½-hour differences between some countries like Australia and New Zealand with other countries like Hong Kong and Korea," she said. "Bedtimes ranged dramatically across cultures."
Mindell and her colleagues analyzed how the parents of 29,287 infants and toddlers, up to 3 years old, responded to questionnaires about their children's bedtimes. Those findings were published in the journal Sleep Medicine in 2010.
The parents were from China, Hong Kong, India, Indonesia, Korea, Japan, Malaysia, the Philippines, Singapore, Taiwan, Thailand, Vietnam, Australia, Canada, New Zealand, the United Kingdom and the United States. They completed the questionnaires between May and June 2006, September and December 2007 and April 2008.
The researchers found that the latest bedtimes were reported among parents in Hong Kong, who on average reported bedtimes about 10:17 p.m., whereas the earliest bedtimes were reported among parents in New Zealand: around 7:28 p.m., on average.
The study was sponsored by pharmaceutical company Johnson & Johnson, and Mindell has served as a consultant for the company.
Bedtimes also appear to vary across European countries, said Sara Harkness, a professor and director of the Center for the Study of Culture, Health, and Human Development at the University of Connecticut.
She was not involved in the Sleep Medicine study but has conducted research on children's activities and bedtimes.
"We certainly did find in our research in Spain that early bedtimes were not common for young children. In fact, on one occasion, our Spanish colleague invited us to watch preschool children in a performance at a local festival starting about 11 p.m.," Harkness said.
"The most dramatic contrast we've seen to this pattern is in the Netherlands, where babies and young children are put to bed at around 6:30 or 7 and expected to sleep through the night in their own bed, often in their own room," she said.
On the other hand, "in small-scale traditional preindustrial societies such as the Kipsigis people of Kenya, where we did research in the 1970s, babies were always in close proximity to caretakers, generally their mother or an older sibling, and they slept anywhere and any time," she said.
Around the world, there are not only differences in when babies snooze but in what happens before they slumber.
Parents try it all to get babies to sleep
In the United States, it's common for parents to prepare their children for bedtime with a soothing bath followed by a lullaby or, for older kids, a book.
Yet around the world, bedtime routines involve a different approach, and in some places, they appear to be less common.
"One of the biggest similarities is that most families include in their child's bedtime routine, for 0-3, some type of feeding, whether it's breastfeeding or bottle-feeding or snacks, and that's consistent across all countries, but if we take that out, there's big differences in activities like bathing," Mindell said, citing her own research.
In the US, "60% of families have a bath as part of their bedtime routine. It's even higher in the United Kingdom at 81%. But somewhere like India, only 13%. In Indonesia, it's only 6%," she said. "They typically bathe in the morning or at another time of the day."
There are also regional differences in which bedtime routines include prayers, Mindell added.
"In the Philippines, 29% of families -- basically one out of three families -- include prayers as part of their bedtime routine," she said. "Whereas some place like Australia, only 6% did. In Indonesia, 30% include prayers as part of their bedtime routine."
Once the time comes to actually get some shut-eye, parents use different approaches to get their children to sleep.
In Korea, Harkness said, parents often sleep with their babies to help them drift into dreamland, but Dutch parents tend to leave their babies alone in their rooms, where the children must learn to put themselves to sleep.
"The Dutch parents in our studies strongly supported a cultural rule of the 'Three R's' of childrearing -- rust, regelmaat, en reinheid, or 'rest, regularity and cleanliness' -- which entailed establishing a firm routine featuring plenty of sleep on a regular schedule from an early age," Harkness said.
Who bed-shares, and who doesn't
Similar differences emerge among bed-sharing practices.
"Co-sleeping is the usual practice in preindustrial societies around the world where there are no special beds for babies to sleep safely by themselves. Co-sleeping on mats on the floor is a cultural norm in Asia, where the family traditionally co-sleeps together in the same room. Mats are brought out at night, then stored during the day so the same room is both a living room and a sleeping room," Harkness said.
"We found more tolerance for co-sleeping for at least part of the night for babies and young children in European communities we studied, but this may have changed more recently following pediatric advice," she said.
In the United States, the American Academy of Pediatrics recommends against sharing a bed with your infant and says "there is insufficient evidence to recommend for or against the use of devices promoted to make bed-sharing 'safe.' "
"The US parents seem to receive more strict guidance, especially from pediatricians, about avoiding co-sleeping," Harkness said. "This is part of a larger set of advice about sleeping arrangements, including not using padded 'bumpers' around cribs, having the baby sleep on its back and not using covers such as quilts or blankets for babies -- all for the same purpose of avoiding the danger of suffocation."
'Bedtime routines are the perfect package'
All in all, bedtime routines can benefit a child's development, Mindell said.
"Bedtime routines are the perfect package for not only sleep, but for promoting positive child development," Mindell said.
"Children who have consistent bedtime routines not only sleep better, but it also promotes things like literacy, attachment, language, bonding and self-care -- all the things that we want children to have, whether or not they live in India or whether they live in the United States," she said.