Thank you all for your thoughtful comments and emails on the last few posts. They have me newly inspired to think about research in areas that have not been touched by developmentalists yet. For this last post about temperament (at least the last for a while), let's think more explicitly about how it may apply to sleep training. I suspect that most of you will be disappointed with the lack of firm guidelines or precise advice that I'm about to give. That's because there's NOTHING out there in terms of good research that has looked at what is the best match between particular child temperaments and particular sleep-training methods. NADA. And I suspect well-designed studies on the subject will NEVER be conducted. Let's just imagine what that would take. It's making my head explode just thinking about it. You'd have to randomly assign families with children who are more "temperamentally sensitive" to a "cry-it-out" group, or a "no-cry training approach" group or a "don't do anything" group. Then you'd have to get families with "easy" kids to be assigned to the same 3 sleep-training groups and do it all over again with "slow-to-warm" or whatever categories you're working with. What parent with a child with ANY temperament will go through with a sleep method they don't think is working for their kid? How can you force this random assignment to stick and for families to go through it. You can't, basically (or it would be very, very difficult and your sample would be horrendously biased). And of course some methods will have to be slightly modified (for ethical reasons, if nothing else) so that they're suitable for the child that cries until he throws up vs the child who doesn't even whimper when the mother leaves the room. And there are SO MANY other factors that could impinge on the "success" or "failure" of these temperament-method matches. WHOA!  But you're not here for a very bad version of a crash-course in Research Design, are you? Sorry. Let's move on.

So, we don’t have enough information from science to suggest a particular approach to sleep training based on children’s temperamental traits. But I think we can broadly consider certain social and emotional features of different types of temperaments that might be relevant to the decisions you make. A child with a "difficult" or more "anger-prone" temperament often becomes embroiled in pivotal issues towards which parent and child confront each other again and again. These emotional hot spots become difficult to navigate around in more sensitive stages in development. It’s the toddler’s JOB to be defiant, at least some of the time. But when a child is defiant most of the time, teaching ANYTHING, not only good sleep habits, can be hell. So I'd suggest dealing with the tougher sleep-training concerns early on with the more difficult kids, before they become entrenched battle zones (not that I have any data on this, but let's say, before the 18-month transition period). For every rule learned, there will be one less issue to fight about later on. This may be particularly important when it comes to bedtime. Difficult babies may have trouble developing regular sleep habits regardless of parents’ philosophies and efforts. That’s why it’s probably most important to get these kids into a regular, predictable bedtime routine as early as possible—definitely before the 18-month HUMUNGOUS cognitive and emotional stage transition (which has everything to do with NEGOTIATING rules and pushing on your boundaries). Also, I would suggest that the difficult, more rambunctious/rebellious kids are the ones you want to really make sure to sleep train during one of the stable developmental periods. You might get away with some slack with an easy kid, but difficult kids will need to take advantage of the less emotional, less challenging optimal windows for change.

Anxious-inhibited children, as described in Part II, won’t have difficulties in as many situations, but the situations that DO prove to be difficult will have a very particular flavour. These kids will have the most trouble dealing with new people and with separations. And these difficulties are likely to improve on their own with age. So, while they're still hyper-sensitive, try to keep these challenges to a minimum. This applies to a huge assortment of considerations including the types of playgroups you join, the ways you deal with daycare drop-offs, and so on. But with sleep, it means that it might be wise for the parent of an anxious-inhibited child to provide extra doses of love and nurturance when sleeping in any new or less-familiar context. This applies to all sorts of sleeping arrangements including spending the night at the grandparents' house, in hotel rooms, having cousins sleep over, napping at daycare and so on. In all these situations, the anxious child will need EXTRA emotional support, even if daily (and nightly) sleep habits at home are firmly established and are associated with no distress. These considerations will be especially important in those stages of development marked by separation distress. So I'm simply (and perhaps obviously) suggesting that you provide your anxious-inhibited child, or your highly reactive and hard-to-soothe child, with loads of familiarity and free access to his parents for protection and security, especially during the 8-11 month transition and the 18-21 month stage. Of course separation issues will create extra challenges for sleep training. So you should definitely avoid sleep training during these two stages. Instead, shoot for the stages of greatest individual autonomy and resilience: 5 – 7 months and 12 – 16 months (we give these stages specific names in the book, but I won't confuse you here). The 5- 7 month stage might be especially well-suited for sleep training these anxious children, as it comes before the child has ever experienced true separation distress. Finally, take care never to combine sleep training with prolonged parental absence or the presence of unfamiliar adults. In other words, it's probably best to not use any sleep-training method that requires you to leave the child alone, probably crying, for long periods of time. For this type of child, these extended separations from parents (often mom) can be immensely distressing and may not, ultimately, teach the child anything about healthy sleep habits. I would even go so far as to say that if you have a die-hard anxious/inhibited child, don’t even think about baby-sitters until after sleep training has settled into a stable and predictable habit.

Finally, if your child is best described as easy, emotionally resilient, less reactive, easily soothed, then relax! You’re going to have the easiest time with most social-emotional challenges, sleep training included. In fact, you might get away with deviating from the sug
gestions we gave in the book and I've given throughout this blog for the most optimal windows for sleep training. Of course, I'd still suggest sticking to our stage recommendations, but if uncontrollable events like returning to work, moving house, or dealing with another child make it difficult to schedule sleep training during a "stable" developmental phase, you’ll still have a reasonable shot at successful sleep training during non-optimal periods. And less serious consequences if things don’t work out.

Did you consider your child's temperament when you began thinking about what methods to use? Do you have an "easy" temperament child that you sleep-trained with no fuss smack-dab in the middle of one of the stages we DON'T recommend? Do you think there's one method out there to sleep-train that's appropriate for all temperament styles? Do you have any lingering questions about temperament you still want to discuss?

I'm going to back up and try not to write the all-encompassing review article that was becoming too big for me and probably too boring for you. Let's consider another one of the most influential scholars in the field of temperament studies and talk a little about her classification system. It's quite different from the last ones we talked about. This work is by Mary Rothbart at the University of Oregon and I think her work is important to consider in the discussion of how
temperament can effect how we sleep train or whether we do so at all. Rothbart thinks about temperament on 2 broad dimensions: the degree of REACTIVITY (in other words, how quickly and intensely does a child react to certain challenges in her environment) and SELF-REGULATION (how quickly and easily does a child control her biological arousal levels and emotions when they're too distressing for her or others).

The extent to which your child is high or low on the REACTIVE dimension is thought to be largely biologically based — it's there at birth and you can see differences in reactivity in newborns. I certainly did with my boys, born 5 min apart. From day 1, if you clapped your hands or something dropped to the floor loudly, one wouldn't even notice, the other would flinch or downright freak out. There's nothing in those styles that I, as a parent, had anything to do with.

But SELF-REGULATION is thought to be more of a developmental acquisition; self-regulation or emotion-regulation skills develop over infancy, toddlerhood and early childhood. And one of the main things that is believed to be a huge part of self-regulation is ATTENTIONAL CONTROL (also called "effortful control"). What do I mean by attentional control? The ability to pay attention to certain aspects of your environment and ignore others; the ability to sustain attention when necessary (like when you need to keep working on a boring problem to solve it); and the ability to shift your attention, especially when frustrated (DUDE the MELTDOWNS we're getting in our house over
crashing leggo constructions that won't fit back together JUST SO is such a great example of this. JUST. BUILD. ANOTHER. BRIDGE! Hmmmm…
maybe I'll film it as a learning tool for the internet). Shifting attention and the control of that shifting is so crucial because the things we choose to attend to can either amplify or dampen our emotional experience (and there's fabulous neuroscientific evidence for the way that our attention amplifies or softens our emotional responses).  As any experienced parent knows, it takes time for children to learn how to control what they will attend to or not, what they'll freak out about or not, how they will respond to an emotional challenge, and so on. And I think (along with many developmentalists) that these regulation skills are among the most critical "habits of mind" that parents (and teachers) can teach their children. We may not be able to do much about how these babies pop out of us in terms of their reactivity or sensitivity to new, challenging or threatening situations, but we CAN help our children learn to deal with the emotions that accompany these challenges.

If you'd like a more thorough review of the temperament literature and a good summary of some of the brain research that's starting to emerge in our field, check out this fairly accessible article in Pediatrics.  It's by Nathan Fox, one of the most well-respected developmental neuroscientists. He's interested in emotional development and children's capacities to regulate their emotions. The article summarizes how researchers generally think about the biological
bases of temperament (and you can access the full article with that
link, btw). The paper is nice because he goes through a bit of a
review of how the original researchers (Thomas and Chess) came up with
their categories and then moves on to other considerations, including
Rothbart's research. He reviews what I have very quickly summarized here: that kids come into the world with
certain propensities to feel emotions either relatively mildly or
intensely (so those initial set points are relatively "inate").
However, the skill of REGULATING these emotions has a whole lot
to do with parenting practices and other "socialization" experiences
(like interactions with teachers and peers). But the article actually refers to studies and data that are too extensive for me to list here.

So… what do you think? Does this way of thinking about children's temperaments or personalities on more emotional dimensions jive with you better than the previous approach, based more on how kids behave? What's your child like? And if you're past MY children's stage of 3.5 crazies, I trust that you will tell me that my previously charming and sweet little boys will indeed learn how to control the OVER-THE-TOP weeping and wailing and HORROR when their blocks fall, they don't get a second ice cream cone, or, dare I say it, THEY. MUST. GO. TO. BED. NOW.

Sleeping issues specifically covered in next post. I promise. But please feel free to think aloud with all of us about how your child's temperament is effecting his sleep… and yours.

I'm sorry. I've been working on some crazy, meta-organizing, what-it's-REALLY-all-about temperament post that will clarify all the limitations and challenges inherent in the temperament research and how it could be all addressed if everyone just got along and listened to me, the great and powerful scientist-mommy who really thinks SHE knows how to design a PERFECT temperament study that would actually inform our understanding of sleep problems with children of different types and… blah, blah, bleh. I've STILL got nothing for you. It's large and complicated and I'm obsessing. So that means that I'm basically too confused to put it all in a neat nutshell for you all. But I'm working on it. Really, I am. Until then, let me recommend a few good books that I think are worth reading about your child's temperament. And let's face it, you'll probably only be interested in READING about you child's temperament (or at least what to do about it) if you have one of those crazy little devils that will grow up to be the most insanely talented artists, the most successful, full-throttle CEOs or your run-of-the-mill criminals. In other words, call it what you will, but most books out there on temperament are focusing mostly on the "difficult", "sensitive" or "spirited" child.  Here are some of the better ones:

• Raising your Spirited Child
• The Highly Sensitive Child
• The Highly Intuitive Child

I can write paragraph-long caveats for each of these books and there are other, great books out there as well on the topic that I haven't linked to because they are not directly related to temperament. Suffice it to say that each of these books that I've linked to DO have some serious limitations, but I think you can learn a good deal from them. At the same time, some of the others I would have linked to have too much of a judgmental angle (although strongly researched) for me to put up here.

I'll be back… either with something on temperament or something completely different because I will have lost the battle with the compulsive editor in my head…

What books have you found useful to understand your child's temperament or personality better?

Let's dive into some of the theoretical approaches to temperament in psychology. This may seem boring to some of you, overly-simplistic to others (I'm often in this camp), or just plain irrelevant to those of you suffering through intense sleep deprivation. All fair criticisms, I think. But I'd like to just get a few ideas out about the broad temperament styles before we all start to concretely speculate about their implications for children's sleep. If nothing else, this post will make you thankful that you skipped that application to grad school in developmental psychology.

I mentioned in Part I of this series of posts on temperament that there are many ways to divide the pie of temperament, and many books have been written on the subject. One of the original systems for delineating temperament styles in infants and young children was developed by Thomas & Chess in the 60s and 70s. It's what I like to call the "three little bears" approach (too hot, too cold, juuuuuust right kinda thing). Here's a reasonable summary of their research approach, the methods they used to categorize kids, and some of the conclusions they came up with.  (It's more complex than I can give credit to in a blog post.) According to these researchers, of the children who could be classified, about two-thirds were labeled “easy” and the remainder were divided almost equally into “difficult” and “slow to warm up.” The easy child adapted smoothly to new experiences, was generally happy, and had few difficulties eating or sleeping. Difficult babies were irritable, fussy, and reactive, they generally cried a lot, and they tended to have irregular eating and sleeping habits. Babies who were slow to warm up would often withdraw from new experiences or people, and they adapted to these experiences only slowly, after repeated exposure. The first groups of children, easy and difficult, probably bring clear images to mind for anyone who’s spent time with children. Indeed, some babies seem to take challenges and novel experiences in stride, whereas others fuss and cry when they are challenged, when their expectations aren’t met, or when they are tired, or hungry, or just plain moody. The "easy" group grow into toddlers who, though rambunctious and defiant to some degree, generally end up cooperating with parents and accepting most situations. Difficult toddlers, on the other hand, can be extremely challenging. They are the ones for whom nothing seems to work, for whom every choice is intolerable, and who fight or resist many parental directives, from putting on their socks to eating what’s in front of them (or eating anything at all except jellybeans and olives). They're also often the ones who are "overly" sensitive to certain foods and to unfamiliar textures, and so on.

The final group, "slow to warm up", seems to apply to children who were more precisely described by Jerome Kagan’s research in the 80s (he's recognized as one of the most prominent developmentalists in the field; he's controversial and damn interesting to boot). Kagan delineated a group of babies who would freeze or withdraw when faced with loud noises, novel sights, and new people. He described these babies as anxious or inhibited. These anxious/inhibited children generally showed a high, regular heart-rate and they would startle very easily and quickly. If we compare “difficult” babies’ and these anxious/inhibited ones, the difficult babies' temperaments seem to revolve around the emotion of anger — they react to many of their challenges by throwing fits of rage or they are often in an angry huff when things don't go their way. But inhibited babies’ predominant emotion is anxiety or fear. They react to strangers with intense shyness, they are often afraid of anything remotely risky (dipping a toe in the water, loud traffic, crawling too far, but especially interacting with new people).

Now remember, I'm referring to infants and young children (we tend to think about temperament as "personality" after early childhood). So what happened to the anxious/inhibited kids when they grew up? A certain proportion of these babies would grow into inhibited, overly-cautious teenagers and adults, a few would develop full-blown anxiety disorders, but the VAST MAJORITY would end up just like most other children, with no real emotional problems at all. So let's be clear here: No one is suggesting that early, biologically-based temperaments do not or cannot change with particular types of EXPERIENCES and exposure to particular environments. Nature and nurture are inseparable and suggesting one trumps the other is silly (it's my blog so I get to say these kinds of sweeping generalizations. And you can — and SHOULD — tell me I'm wrong if you think so).

So these are some of the VERY basic ways that the temperament pie has been sliced. MANY other systems of classification have been put forward as well, of course, but a surprising number don't differ significantly from these basic types. So how does this all relate to sleep? Well, that's the trouble: I don’t have enough information/data/research to suggest a particular approach to sleep training based on children’s temperamental traits. There’s simply no empirical research that has tried to identify the best match between different temperamental styles and different sleep training approaches, nevermind matching these different styles to the best TIME to sleep train. However, we can speculate, (and Marc and I did, in the book) why certain children with various temperaments might respond better or worse to some sleep training strategies administered at certain periods in development.

What are some of your best guesses? How do you think your chid's temperament has influenced his sleep habits? Did you change your mind about the methods or the timing of sleep training when you understood your child's temperament better? Do you think that one particular method or one particular stage to sleep train is most appropriate for all kids, no matter their temperamental style?

This week, I'd like to focus these posts on the issue of temperament. So, way back when I first started this blog, I provided this caveat. Basically, I acknowledged that all children are indeed unique to some extent, but this blog would be largely discussing how remarkably SIMILAR children can be in terms of the developmental stages through which they grow. Somewhere in that early post, however, I did promise to address how developmental psychologists think about DIFFERENCES among children. Surely, some of you have read a description I've written about the "typical" 9-month old and have shaken your head, not seeing anything similar in your child. Or, even more likely, you've read about the terrible, oh-so-sensitive time windows in development that I have suggested you avoid sleep training AT. ALL. COSTS.  And one of those windows was precisely when you last sleep-trained, with no problems whatsoever and no heartache for you or your baby. I know of a couple of these cases personally, so I know they're out there. The developmental stages I've outlined here have very strong empirical support. There have been decades of studies conducted on the remarkable predictability of cognitive and emotional changes that occur in childhood. But all these studies also show that there ARE differences among children and not ALL children at ALL times conform to either the timing or the character of these stages.

Both as a developmentalist and as a parent (and especially as a parent of twins!) I am very aware of how different children can be. Some individual differences are at least partially built into the child’s nervous system, generally through genetic influences. These differences, usually referred to as temperament, are thought to be evident early in the child's life, if not right from birth. Temperamental differences are thought to be biologically-based and psychologists for decades have been trying to understand, categorize, explore, predict and basically figure out WHY some kids have certain temperaments while others have different ones. We've also been trying to figure out whether some temperaments predict better or worst outcomes for some children and not others. But there's still A LOT of debate about temperamental differences and there's almost nothing out there on how these differences impact on sleep habits. That won't stop me from speculating though…

The interaction between “nature” (genes) and “nurture” (experience) is what makes temperament so difficult, complex, and fascinating to study. For example, children who are anxious or inhibited in the middle of the first year sometimes end up as anxious/inhibited adolescents and adults, but more often end up indistinguishable from their peers. The outcome seems to depend on their social experiences. And the tendency toward depression, while stamped in genes that govern brain development, only leads to depression in certain individuals. Others grow up without depression, due in large part to the nurturance and support of parents and other caregivers.  So, the “finished product” of temperament comes from an ongoing spiral of influence between genes and environment. But temperamental tendencies, and their biological foundations, are clearly seen in late infancy and early childhood, and these differences greatly affect how children will respond to emotional challenges such as sleep training. In turn, the impact of such challenges on the development of personality is huge. And that’s why it’s of utmost importance to try to tailor emotional challenges (like sleep training) to your child’s temperamental vulnerabilities.

In the next couple of posts, I'll be discussing some of the basic research in this area and it would be great if you could join me in discussing/speculating/musing about how temperamental differences could make a difference in your child's sleep training experience.