Are you struggling with infant sleep problems? Baby sleep is different than adult sleep. A lot of the stuff that drives us crazy is developmentally normal behavior.
For example, newborns need to feed frequently (8-12 times every 24 hours), and the transition to longer, consolidated bouts of sleep is gradual.
In general, we shouldn't expect babies to sleep for more than 4-5 hours at a stretch until they are at least 3 months old.
But that doesn't mean we can't improve things. On the contrary, there's a lot we can do.
Might your baby's sleep troubles be caused by a medical condition? That's possible, so you might want to review these common infant medical problems that interfere with sleep.
But in this article we'll focus on other culprits -- the everyday stumbling blocks on the path to easier, more restful nights.
Here is a list of ten things that might be going wrong, and what you can do about them.
At the end, I talk about that controversy that every new parent faces -- the "cry it out" controversy -- and then I sum things up with a checklist of good practices for avoiding infant sleep problems.
First things first: Does your baby appreciate that nighttime is for sleeping? If not, you're fighting an uphill battle.
Most infants don't develop strong, hormonally-driven circadian rhythms until they are 12 weeks old, and some babies take considerably longer (Jenni and Carskadon 2005; Jenni et al 2006).
You might assume that this is one of those developmental things we just have to wait out. But that's not quite true. The evidence suggests we have help young babies attune themselves faster. If we lay the right groundwork early on, we may avoid some infant sleep problems later on.
Be sure to try these tactics:
Experiments show that blue light is particularly effective at blocking the brain's production of melatonin, a hormone that promotes sleepiness. A little exposure to blue light can delay sleepiness for an hour or more. And it affects adults as well as children!
You can read more about artificial lighting -- and how to cope with it -- in this Parenting Science article about the effects of light-emitting entertainments and devices. Tackling blue light exposure can improve the sleep of everyone in your family, so it's worth taking seriously.
For more tips, see "How to help baby adapt to the 24-hour day" in my article about newborn sleep.
This is one reason why newborns sleep in short bouts. They get hungry!
What can we do about it? Not much, not when our babies are very young. They need frequent feedings in order to grow and thrive.
But you can probably improve your own ability to sleep with smart timing.
Dream feeding is a technique in which you provide your baby with a big meal immediately before you attempt to fall asleep for yourself. The idea to help your baby "tank up," so your baby (and you) will sleep longer.
Another tactic is to introduce brief delays before beginning those middle-of-the-night feeds. For example, instead of feeding your baby immediately, you might change your baby's diaper first. As babies get older, this might help them break the association between night wakings -- which all babies experience -- and feeding.
Do these tactics work? One experimental study suggests they do.
Researchers recruited 26 families, and assigned half the parents to offer their babies a big meal between 10pm and midnight. They were also told to avoid feeding babies immediately after they woke up during the night.
In addition, parents were instructed to expose their babies to strong cues about the natural, 24 hour day.
The intervention appeared to be very successful. Eight weeks after training began, 13 out of 13 infants in the treatment group were sleeping quietly from midnight to 5am (Pinilla and Birch 1993). Only 3 out of 13 control infants were doing so.
It sounds promising, but keep in mind: This is a small study that needs replication.
Moreover, the study design doesn't permit us to tell which of the interventions were important, and we don’t know if the effect was long-lasting. It's also unclear if going 5 hours without feeding is in the best interest of every 8-week old infant.
But as long as your baby is getting enough food and fluids -- and your pediatrician approves -- these tactics are worth trying. For more information about nursing young babies, see this Parenting Science article about feeding infants on cue.
And if you are interested in trying out dream feeding, check out my evidence-based guide to dream feeding.
Research suggests that some parents make the hour leading up to bedtime too exciting, and this could make it harder for babies to nod off.
Rambunctious play and energetic talk can rev up your baby's sympathetic nervous system—the system in charge of keeping him or her alert.
In addition, research suggests that screen time could cause trouble. In a recent survey of 715 British parents, researchers found that babies who spent time playing with touch screens (on phones and other devices) took longer to fall asleep at night.
These babies also had shorter nocturnal sleep times. For every additional hour that an infant used touch screens, the infant was likely to sleep 26 minutes less at night (Cheung et al 2017).
So researchers recommend that parents make the last 2-3 hours
before bedtime quiet and calm (e.g., Glaze 2004).
But exciting interpersonal activities aren't the only sources of trouble. In a recent survey of 715 British parents, researchers found that babies who spent time playing with touch screens (on phones and other devices) took longer to fall asleep at night.
These babies also had shorter nocturnal sleep times. For every additional hour that an infant used touch screens, the infant was likely to sleep 26 minutes less at night (Cheung et al 2017).
The researchers didn't collect information about when babies used touch screens, and can't say for sure if touch screen use contributes to infant sleep problems.
But the blue light emitted by tablets and other electronic devices is known to delay drowsiness. So it's plausible that this blue light, and the stimulating nature of media content, are to blame.
What should we do?
It makes sense to be cautious about screen time. It's also a good idea to avoid excitement in the evening (e.g., Glaze 2004), and to consider introducing a soothing bedtime routine (see below).
Young children may sleep longer at night when they observe regular bedtimes (Staples et al 2015).
Research also suggests that children fall asleep faster, and spend less time awake at night, when their parents implement a consistent bedtime routine at night -- like bathing, quietly dressing for bed, and reading a bedtime story (Mindell et al 2015).
So if you're struggling with infant sleep problems, it's worth introducing a bedtime routine. Indeed, in one experimental study, parents improved infant sleep problems after introducing bedtime routines (Mindell et al 2009).
But are regular bedtimes really necessary to avoid sleep trouble?
Cross-cultural studies suggest otherwise. In many parts of the world bedtimes are fluid or irregular, and babies go to sleep without fanfare (e.g., Morelli et al 1992; Ottaviano et al 1996).
Indeed, it's the norm among hunter-gatherer societies -- the peoples whose life-ways most closely resemble those of our ancestors. And hunter-gatherers are remarkable for their lack of sleep complaints (Yetish et al 2015; Samson et al 2017).
It's evident, then, that there is more than one way to achieve healthy sleep patterns. But before you conclude that anything goes, keep in mind these crucial points.
First, irregular bedtimes can cause trouble if they lead to irregular morning wake-up times.
If you wake up at different times each morning, it can disrupt your circadian rhythms. Maybe that's why anthropologists have observed morning regularity among hunter-gatherers: They tend to get up at the same time each morning regardless of when they fell asleep the night before (Yetish et al 2015).
Second, babies might get less sleep at night -- a deficit they'll need to make up during the day.
This isn't perceived as a problem in many traditional societies, where babies are expected to take short daytime naps while being carried in a sling. Parents, too, may sometimes take naps to compensate for a short night's sleep (Worthman and Melby 2002; Samson et al 2017).
But you? If your schedule doesn't permit this flexibility, irregular bedtimes could leave you short-changed.
So it really isn't anything goes. Babies and adults alike benefit from waking up at the same time each morning, so that's something to aim for. And when irregular bedtimes lead to shorter nighttime sleep bouts, be prepared to make up for lost sleep during the day.
When should babies go to bed? It can be hard to figure out.
Some parents overestimate infant sleep requirements, or try to force bedtime on an infant that isn't sleepy.
That's bad for a couple of reasons. In the short-term, the baby resists bedtime, and everyone is unhappy. In the long-term, your child is learning to associate bedtime with the failure to fall asleep. It could be a recipe for developing bedtime resistance and insomnia (LeBourgeois et al 2013).
Other parents keep their babies awake too long, making their babies irritable.
It can be an easy mistake to make, especially if your baby seems very active and energetic. Isn't that proof that your baby isn't yet ready for sleep?
Maybe, but there is another possibility: Your baby might be hyper-reactive or "overtired." If so, you're baby's behavior is deceptive: He's not alert because he's well-rested. He's alert because his stress response system is stuck on high gear.
What to do? If you're uncertain, review these signs of infant tiredness, and consult this Parenting Science article about the range of sleep times observed in normal, healthy babies. It will help you home in on your baby's needs.
Then, if you suspect your baby's bedtime is too early, try these gentle infant sleep training solutions. They are safe to use, and don't involve any "cry it out" tactics.
If overtiredness is the problem, pick an earlier bedtime, and help your baby wind down by introducing some soothing, low-key bedtime rituals. For tips, see my article about solving bedtime problems.
Babies sometimes make noises--and may even cry out--when they are still asleep or only partially aroused. In other words, babies are "sleep talkers."
So it's easy for newbies to make a crucial mistake -- assuming that a baby is awake and signalling for attention when she's really just sleeping in a fitful, noisy way.
If you intervene under these conditions -- touch and talk to your baby -- you may be doing the very thing you most want to avoid: Waking up a sleeping infant!
That's one reason to be cautious before interacting with your baby. And here's another:
Video recordings of sleeping infants reveal that babies as young as 5 weeks can spontaneously resettle themselves after waking up in the middle of the night (St. James Roberts et al 2015).
During the study in question, babies sometimes went back to sleep quietly. In other cases, the infants cried or fussed briefly (for about one minute) before going back to sleep on their own (St. James Roberts et al 2015).
But either way, these babies fell back to sleep on their own, without coaching or marked distress. That's the sort of thing you want to promote.
So intervening too soon can backfire. You think you are being proactive, responding quickly so your baby will be able to go back to sleep quickly. But instead you are awakening a sleeping baby, or interfering with a drowsy baby who was about to nod off. Ouch.
To avoid becoming the cause of infant sleep problems, don't jump in at the first signs of movement
We've seen how too much stimulation can cause trouble at bedtime. Parents can also cause infant sleep problems by creating too much excitement after a baby has awakened during the night.
Babies are social creatures, and are easily stimulated by talk and other forms of communication.
So if you want your baby to go back to sleep quickly, avoid engaging him or her in conversation or play. As you tend to your baby's nighttime needs, keep things comforting, but dull and quiet. And don't forget to avoid those artificial lights. Keep things as dark as possible.
It's easy to get off-track when you are frustrated or tired.
Sometimes you might use overly-stimulating soothing techniques. Other times -- when it seems that nothing works -- you might withdraw from your baby altogether (France and Blampied 1999). It's human nature, but it's confusing for the baby, and it can make infant sleep problems worse.
To help avoid this scenario, take the time to create a single, consistent approach to your infant sleep problems.
Research the science of infant sleep patterns, and decide what approach is best for you and your baby.
Thinking things through ahead of time will help you stick to the plan, and may have additional psychological benefits for you.
Parenting studies suggest that getting informed can boost your sense of competence and confidence, and protect you from feelings of frustration and despair (Heerman et al 2017).
Sleep pressure (the physiological urge to sleep) builds up the longer we've been awake. So it shouldn't surprise us if a baby -- having awakened from a long nap only a couple of hours earlier -- has trouble falling asleep at bedtime.
If this seems to be the trouble, try extending the last waking period of your baby's day.
That may seem hard to do if you've got a drowsy baby at 5pm; but remember, you don't have to arrive at the perfect schedule all at once.
You can work towards the goal in steps, trying to make the last nap of the day end at an increasingly earlier time over the course of a week or so.
When parents have managed to lengthen waking time before bedtime, their babies have required less help settling down and experienced fewer infant sleep problems (Skuladottir et al 2005).
Sleep science has proven the point: Everybody wakes up during the night, and we do it quite frequently, even if we don't remember these wakings the next day.
So eliminating night wakings isn't a realistic goal. Rather, we should focus on making night wakings less disruptive.
As mentioned above, research shows that babies sometimes resettle themselves without becoming stressed or waking up other people. What can we do to promote this behavior?
One crucial tactic, noted in #4, is to stop undermining
these spontaneous acts of re-settling. Don't jump in prematurely. Your baby
might actually be asleep, or on the verge of falling back to sleep on his or
her own. By intervening too soon, you can create infant sleep problems.
But can we go further?
In some Western countries parents are advised to avoid soothing their babies to sleep.
For instance, Richard Ferber argues that parental soothing trains babies to associate sleep with parental intervention (Ferber 2006). As a result, children don't develop their own, self-soothing abilities. When babies wake up during the night (and all babies do), they cry until their parents come to their aid.
The remedy, according to this argument is to follow certain rules. Don't let the baby fall asleep in your arms. Instead, at bedtime, put your baby to bed before he or she has fallen asleep.
What does the research tell us? When babies fall asleep at the breast--or are put to bed after they have fallen asleep--babies are less likely to soothe themselves back to sleep when they awaken again during the night (e.g., Anders 1979; Anders et al 1992; Ferber 1986; Goodlin-Jones et al 2001).
In addition, researchers have found that parents who feed, hold, or rock their babies to sleep tend to report more night wakings (Anuntaseree et al 2008; Mindell et al 2010).
That sounds like evidence in support of reduced parental soothing at bedtime. But there's an obvious complication: Babies often cry or protest when caregivers withdraw.
It's a natural behavior. Throughout human history, babies have stayed in close proximity to their caregivers. Being left alone meant something was wrong. A baby was at risk for neglect, abandonment, or predation (Hrdy 1999).
So it's little wonder that our ancestors evolved emotional and behavioral responses to separation -- responses that would help ensure that babies stayed close (Panksepp 1998). What, then, should we do when babies cry?
Ferber has proposed his own solution, which is to leave the baby alone for increasingly lengthy intervals, ignoring cries, until the infant learns to give up (Ferber 2006).
It's not intended for very young babies. Researchers warn that such sleep training should not be attempted until infants are at least 6 months old (Owens et al 1999; France and Blampied 1999).
Moreover, the American Academy of Pediatrics recommends that parents share a bedroom with their babies for at least six months after birth because it may lower the risk of SIDS and "facilitate…comfort and monitoring of the infant" (Moon et al 2016).
But when it comes to making nighttime less disruptive, this
method -- called "graduated extinction" -- has a successful track
record. Babies become less likely to cry in the middle of the night when they
awaken. Parents report fewer infant sleep problems.
This can be a relief to desperate parents. But many people reject the approach. It's stressful to implement, and critics worry about the possible effects of enforcing its central features -- (1) babies left alone, unable to perceive the immediate presence of caregivers, and (2) parents acting as if they are insensitive to the baby's distress.
Major media headlines to the contrary, studies haven't yet supplied us with strong evidence about these concerns.
One highly-publicized study tested the long-term effects of sleep training on more than 170 babies, but did so by lumping together several different training strategies, including a program that didn't involve leaving infants alone (Price et al 2012).
Thus, we can't know if families who used graduated extinction experienced different outcomes than families who used other methods -- like those that kept babies and parents together in the same room.
In addition, this study failed to determine if parents in the control group attempted sleep training. This, too, is crucial, because it means we can't draw conclusions about a failure to detect differences between groups.
Maybe outcomes were similar because treatments were similar: Babies in both groups were exposed to a mixed bag of sleep training techniques.
A more recent study presents similar interpretative problems (Grandisar et al 2016). The researchers took the helpful step of distinguishing between graduated extinction and other types of sleep training.
But they didn't measure what parents assigned to the control condition did with their babies. Nor did they keep track of where babies slept with respect to their parents -- alone or in a shared room.
Moreover, this was a much smaller study, and one marked by substantial amounts of missing data, as well as some discrepancies in the published numbers.
For example, at one time point during the study, almost half the families failed to participate. Researchers filled in the missing data with their own estimates (Grandisar, personal communication).
And it's interesting to reflect on results that the popular press largely ignored.
The researchers tested for attachment security at the end of the study, and found that only 7 out of 13 (54%) of "graduated extinction" babies were scored as securely attached to their parents. By contrast, babies in the control group fared a bit better: 5 out of 8 babies (62%) were scored as securely attached.
We can't draw any conclusions from this difference. The sample sizes are too small, and six families chose not to participate in this final test, which may have biased the results.
instance, what if having a securely-attached baby made parents more
inclined to participate? Or less inclined? But it underscores the
difficulty in making inferences from small studies with missing data.
So as I write this in May 2017, we're still a long way from settling questions about the effects of graduated extinction, especially for parents concerned about leaving babies alone and unable to perceive the presence of caregivers.
That's important because there are other approaches
of sleep training that don't involve leaving babies alone, and these approaches
have similarly successful track records. You can read about these methods in my article, "Gentle infant sleep training."
Furthermore, scientific surveys indicate that babies don't have to sleep in their own rooms to develop quieter sleep habits.
In places like Hong Kong, babies and children often share a room with others. In many cases, they share a bed with a parent. But researchers have found no links between sleep location and night wakings (Yu et al 2017).
It appears to be the use of active soothing measures -- like feeding or rocking a baby to sleep -- that is linked with trouble. Not necessarily parental presence.
So if you want to encourage your baby to self-soothe, it's worth taking a look at these sleep training alternatives to graduated extinction.
And keep in mind the work of Douglas Teti, who has found that one of the most important predictors of infant sleep problems is whether or not parents are emotionally available at bedtime -- responding with sensitivity to a baby's needs, and projecting a calm, reassuring mood (Teti et al 2010).
Regardless of whatever else you might do, and whatever sleep arrangements you adopt, maintaining emotional availability at bedtime can help your baby settle down.
Adams LA and Rickert VI. 1989. Reducing bedtime tantrums: Comparison between positive bedtime routines and graduated extinction. Pediatrics 84(5): 756-761.
Anders TF. 1979. Night waking in infants during the first year of life. Pediatrics 63: 860-864.
Anders TF, Halpern LF, and Hua J. 1992. Sleeping through the night: A developmental perspective. Pediatrics 90(4): 554-560.
Anuntaseree W, Mo-suwan L, Vasiknanonte P, Kuasirikul S, Ma-a-lee A, Choprapawan C. 2008. Night waking in Thai infants at 3 months of age: association between parental practices and infant sleep. doi: 10.1007/s12519-017-0025-6. [Epub ahead of print]
Cheung CH, Bedford R, Saez De Urabain IR, Karmiloff-Smith A, Smith TJ. 2017. Daily touchscreen use in infants and toddlers is associated with reduced sleep and delayed sleep onset. Sci Rep. 13;7:46104.
Fauroux B. 2007. What's new in paediatric sleep? Paediatr Respir Rev. 8(1):85-9.
Eckerberg B. 2004. Treatment of sleep problems in families with young children: effects of treatment on family well-being. Acta Paediatr. 93(1):126-34.
Ferber R. 1986. Sleepless child. In: C. Guilleminault (ed), Sleep and its disorders in children. New York: Raven Press, pp. 1410163.
Ferber R. 2006. Solving your child’s sleep problems: New, revised, and expanded edition. New York: Fireside.
Ferber SG, Laudon M, Kuint J, Weller A, Zisapel N. 2002. Massage therapy by mothers enhances the adjustment of circadian rhythms to the nocturnal period in full-term infants. J Dev Behav Pediatr. 23(6):410-5
France KG. 1992. Behavior characteristics and security in sleep disturbed infants treated with extinction. J Pediat Psychol 17: 467-475.
France KG and Blampied NM. 1999. Infant sleep disturbance: Description of a problem behaviour process. Sleep Medicine Reviews 3(4): 265-280.
Glaze DG. 2004. Childhood insomnia: Why Chris can’t sleep. Pediatric Clin N Amer 51: 33-50.
Goodlin-Jones BL, Burnham MM, Gaylor EE, and Anders TF. 2001. Night-waking, sleep organization, and self-soothing in the first year of life. J Dev Behav Pediatrics 224(6): 226-233.
Grandisar M, Jackson K, Spurrier NJ, Gibson J, Whitham J, Sved Williams A, Dolby R, Kennaway DJ. 2016. Behavioral Interventions for Infant Sleep Problems: A Randomized Controlled Trial. Pediatrics 137(6).
Heerman WJ, Taylor JL, Wallston KA, Barkin SL. 2017. Parenting Self-Efficacy, Parent Depression, and Healthy Childhood Behaviors in a Low-Income Minority Population: A Cross-Sectional Analysis. Matern Child Health J. 2017 Jan 13. doi: 10.1007/s10995-016-2214-7. [Epub ahead of print]
Hrdy SB. 1999. Mother nature: Maternal instincts and how they shape the human species. New York: Pantheon Books.
Jenni OG and Carskadon MA. 2005. Normal human sleep at different ages: Infants to adolescents. In: SRS Basics of Sleep Guide. Westchester, Illinois: Sleep Research Society, pp. 11-19.
Jenni OG, DeBoer T, and Acherman P. 2006. Development of the 24h rest-activity pattern in human infants. Infant behavior and development 29: 143-152.
LeBourgeois M, Wright, Jr., KP, LeBourgeois OP, Jenni OG. 2013. Dissonance Between Parent-Selected Bedtimes and Young Children's Circadian Physiology Influences Nighttime Settling Difficulties. Mind, Brain, and Education 7(4): 234-242.
Levesque BM, Pollack P, Griffin BE and Nielsen HC. 2000. Pulse oximetry: What’s normal in the newborn nursery? Pediatric pulmonology 30(5): 406-412.
Luddington-Hoe SM, Cong X, and Hashemi F. 2002. Infant crying: nature, physiologic consequences, and select interventions. Neonatal Network 21(2): 29-36.
McKenna JJ and McDade T. 2005. Why babies should never sleep alone: A review of the co-sleeping controversy in relation to SIDS, bedsharing and breast feeding. Paediatric Respiratory Reviews (2005) 6, 134–152.
Mindell JA, Kuhn B, Lewin DS, Meltzer LJ, Sadeh A and the American Academy of Sleep Medicine. 2006. Behavioral treatment of bedtime problems and night wakings in infants and young children. Sleep 29: 1263-1281.
Mindell JA, Li AM, Sadeh A, Kwon R, Goh DY. 2015. Bedtime routines for young children: a dose-dependent association with sleep outcomes. Sleep. 38(5):717-22.
Mindell JA, Telofski LS, Wiegand B, Kurtz ES. 2009. A nightly bedtime routine: impact on sleep in young children and maternal mood. Sleep. 32(5):599-606.
Mitchell EA, Thompson JMD. 2003. Snoring in the first year of life. Acta Paediatrica, 92(4), 425-429.
Morelli GA, Rogoff B, Oppenheim D, and Goldsmith D. 1999. Cultural variation in infants’ sleeping arrangements: Questions of independence. Developmental Psychology 28: 604-613.
Ottaviano S, Giannotti F, Cortesi F, Bruni O, Ottaviano C. 1996. Sleep characteristics in healthy children from birth to 6 years of age in the urban area of Rome. Sleep 19: 1-3.
Panksepp J. 1998. Affective Neuroscience: The Foundations of Human and Animal Emotions. New York: Oxford University Press.
Pinilla T and Birch LL. 1993. Help me make it through the night: behavioral entrainment of breast-fed infants' sleep patterns. Pediatrics. 91(2):436-44.
Philbrook LE, Hozella AC, Kim BR, Jian N, Shimizu M, Teti DM. 2014. Maternal emotional availability at bedtime and infant cortisol at 1 and 3 months. Early Hum Dev. 90(10):595-605.
Price AMH, Wake M, Epi GD, Ukoumunne OC, Hiscock H, Epi GD. 2012. Five-Year Follow-up of Harms and Benefits of Behavioral Infant Sleep Intervention: Randomized Trial. Pediatrics. 130(4):643-51.
Owens JL, France KG, and Wiggs L. 1999. Behavioural and cognitive-behavioural interventions for sleep disorders in infants and children: A review. Sleep Medicine Reviews 3(4): 281-302.
Pantley E. 2002. The no-cry sleep solution: Gentle ways to help your baby sleep through the night. New York: McGraw-Hill.
Reid MJ, Walter AB, and O’Leary SG. Treatment of young children’s bedtime refusal and nighttime wakings: A comparison of “standard" and graduated ignoring procedures. Journal of Abnormal Child Psychology 27: 5-16.
Sadeh A. 1994. Assessment of intervention for infant night waking: Parental reports and activity-based home monitoring. J Consult Clin Psychol 62(1):63-8
Samson DR, Crittenden AN, Mabulla IA, Mabulla AZ, Nunn CL. 2017. Hadza sleep biology: Evidence for flexible sleep-wake patterns in hunter-gatherers. Am J Phys Anthropol. 162(3):573-582.
Sears W and Sears M. 1996. The fussy baby book: Parenting your high-need child from birth to age five. New York: Little, Brown and Company.
Skuladottir A, Thome M, and Ramel A. 2005. Improving day and night sleep problems in infants by changing day time sleep rhythm: A single group before and after study. Int J Nurs Stud. 42(8): 843-850.
Staples AD, Bates JE, and Petersen IT. 2015. Ix. Bedtime routines in early childhood: prevalence, consistency, and associations with nighttime sleep. Monogr Soc Res Child Dev. 80(1):141-59.
Teti DM, Kim BR, Mayer G, Countermine M. 2010. Maternal emotional availability at bedtime predicts infant sleep quality. J Fam Psychol. 2010 Jun;24(3):307-15
Worthman CM and Melby M. 2002. Toward a comparative developmental ecology of human sleep. In: Adolescent Sleep Patterns: Biological, Social, and Psychological Influences, M.A. Carskadon, ed. New York: Cambridge University Press, pp. 69-117.
Yetish G, Kaplan H, Gurven M, Wood B, Pontzer H, Manger PR, Wilson C, McGregor R, Siegel JM.2015. Natural sleep and its seasonal variations in three pre-industrial societies. Curr Biol. 25(21):2862-8.
Yu XT, Sadeh A, Lam HS, Mindell JA, Li AM. 2017. Parental behaviors and sleep/wake patterns of infants and toddlers in Hong Kong, China. World J Pediatr. 2017 Mar 22. (epub ahead of print)
this text are derived from an earlier (2008) Parenting Science
article with the same title, "Infant sleep problems: an evidence-based guide."
Image credits for infant sleep problems
The following images are protected by this creative commons license, and should be attributed to the creators listed:
Image of sunset by fdecomite / flickr
Image of baby with tablet by Humbolthead / flickr
Image of baby staring at viewer by Jim Champion / flickr
Image of baby gazing out window by Nana B. Agyel / flickr
Image of baby sleeping in the sunlight by shawn / flickr
Montage of baby-wearing - historical images and Hadza photograph by Idobi
Father soothing infant by Andres Nieto Porras / wikimedia