Friday, September 30, 2011

Off to a Training! Again?

We're off to Orange County in beautiful Southern California for another training! We'll be back next week with a new post.

Tuesday, September 27, 2011

Poor Infant Sleep does not Increase Later Obesity Risk

By Jennifer Goldbronn, MAS, RD

With childhood obesity rates at epidemic levels in developed countries around the world, there is great interest in identifying successful interventions to decrease obesity risk. Recently, researchers have suggested a potential association between poor sleep and later obesity risk. Today we’ll discuss this potential association and present information from a new study examining the association between improved sleep in infancy and obesity risk at age 6 years.

In a previous post we wrote about a research article linking short sleep duration to increased risk of obesity. (Bell 2010) In this study, the association found was not specific to infants because the authors grouped together kids of all different ages.

Sleep and Obesity: Why the Link?

Despite all of the research about the relationship between sleep and obesity, there is no evidence showing a cause and effect relationship. Researchers have theories for the associations they’ve found, including: (1) if children are sleeping less, their bedtimes may be later allotting them more time to take additional calories in the evening or (2) children may be less physically active because of fatigue from shorter sleep duration. Unfortunately, at this time, these explanations are just speculation and while some studies have shown associations between BMI and chronic short sleep in older children, none have focused on how sleep in infancy may or may not affect later risk for obesity.

The Study

In a recent Australian study, providing education to parents of infants with parent-reported sleep “problems” at 7-8 months resulted in improved infant sleep organization but did not reduce obesity risk at age 6. (Wake et al. 2011) A Sleep “problem” was identified by asking 2 questions: (1) “Over the last 2 weeks, has your baby’s sleep generally been a problem for you? (yes/no)” and (2) if yes, the parent rated the severity of the problem on a 7-point scale with 1-2 mild and 5-7 severe.

The Study Intervention

Nurses were trained to provide a short sleep education to parents at the 8-month well-child check-up. Topics discussed included normal infant sleep patterns and sleep problems and potential causes. Nurses helped parents to identify possible solutions and created an individualized sleep management plan for each family. Mothers were asked to complete a 2-week sleep diary and to choose one of two sleep strategies: “controlled crying” or “camping out.” Mothers also attended 1-2 follow up sessions with the nurse where sleep patterns and improvements were identified and new goals were set.

The controlled crying strategy involved parents responding to their infants’ cries at increasing time intervals to allow the infant to learn to self-soothe. (see note below) Parents choosing the “camping out” strategy were instructed to initially stay with the infant while he or she fell asleep, slowly moving farther away over the following days, until the infant could fall asleep without the parent nearby.

Results of the Intervention

Parents in the intervention group reported fewer infant sleep “problems” at 10 months (56% vs. 68%) and 12 months (39% vs. 55%) compared to control groups. Intervention parents also reported fewer and shorter night-wakings than control parents. However, sleep duration was similar in both groups.

Although the sleep intervention did decrease parent-reported “sleep problems” and night wakings, there was no effect of the intervention on obesity at age 6. Both intervention and control groups’ BMI and waist circumference were similar. After the study was completed, the researchers looked back at the data to see if there was any association between childhood sleep duration and BMI. They found no association between sleep duration at 7, 10, 12 months or 6 years with obesity at age 6.

The Bottom Line:

According to recent data, your baby’s sleep patterns at night will likely not affect his risk of obesity in later childhood. We know (from experience) that some of you may be very tired right now and hoping for a solution to help your baby sleep better. Our best advice: know what to expect from your baby’s sleep patterns by reading our posts about how sleep patterns change with age and learn some ways to get yourself a little more rest.

Remember, you can’t change the rate at which your baby’s body matures and learns to sleep for longer stretches, but you can change how you react to it! Arm yourself with the knowledge and know that this too shall pass.

Note: We are not advocating letting your baby cry! We are simply reporting the methods used by the authors of the referenced study. Also, it is important to note that this intervention was carried out with older infants, ages 8-10 months; most infants this age have the ability to sleep a 6-8 hour stretch at night, but they may wake if they need something or to practice their new found motor skills.
While we do not advocate parents letting their babies cry for long periods, also known as the “cry it out” approach, parents of older babies can encourage them to learn self-soothing skills. For example, putting your baby to sleep in his crib drowsy, but awake may help him learn to soothe himself to sleep. However, keep in mind that, in a separate study, only about half of 12 month olds were able to self-soothe after awakening during the night. The other half needed their parents’ help to get back to sleep. (Burnham et al. 2002)

1. Bell J, Zimmerman F. Shortened Nighttime Sleep Duration in Early Life and Subsequent Childhood Obesity. Arch Pediatr Adolesc Med 2010; 164: 84-845.
2. Wake M, Price A, Clifford S, Ukoumunne OC, Hiscock H. Does an Intervention that improves infant sleep also improve overweight at age 6? Follow-up of a randomized trial. Arch Dis Child. 2011;96:526-532.
3. Burnham MM, Goodlin-Jones BL, Gaylor EE, Anders TF. Nighttime sleep-wake patterns and self-soothing from birth to one year of age: a longitudinal intervention study. J Child Psychol Psychiatry. 2002;43(6):713-25.

Friday, September 23, 2011

A Quarter of a Million Page Views!

This week, Secrets of Baby Behavior will pass another milestone - a quarter of a million page views! At just over 2 1/2 years old, interest in our blog has continued to grow. Thanks to all of you who have been with us since the beginning and a big welcome to all of our new readers.We encourage all of our new readers to review the basics and then use the key words on the left to find the topics that are of most interest to you. Some of our earliest readers must have preschoolers now! We appreciate all you've done to spread the word about us...hmmm, I wonder what we'll do when we hit a milllion!

Tuesday, September 20, 2011

White Noise and Infant Hearing

A few weeks ago we wrote a post about hearing in our babies' senses series. For today’s post we are going to answer a reader question about white noise. Here is the comment we received:

“Do you know very much about the effects of white noise on babies? I've heard that it can slow down their hearing development? There are so many devices [white noise machines] sold though, and not much mentioned. We've been using it in our room with our 4 month old for at least 2 months now and just read that. I tried to do some research, and only found one study on some mice in the 90's.”

After reviewing the literature, we also could not find studies showing that white noise is harmful for human infants. The one study we did see was very small and tested the effects of continuous (24 hours per day from day 7 of life) white noise on rat pups (baby rats). Continuous exposure to white noise (70 decibels) was found to cause delayed development of the auditory cortex, an important structure in processing speech sounds. However, it’s important to note that the results of this study cannot be inferred to human infants exposed to white noise during a particular time of day. Why? Not only do human infants develop differently than rat pups, but this study only looked at non-stop exposure to white noise, not short term exposure during naptime or nighttime sleep. Common sense tells us that babies need to hear more than white noise. Some low-level white noise is safe for babies as long as it is not continuous and they are exposed to lots of different sounds throughout the day, especially human voices. Talking and reading to your baby every day is a great way to ensure proper development of your baby’s hearing.

Safe Hearing for Infants
Decibels (dB) are the measurement of the loudness of sounds. How loud the noise is plus the length of exposure to the sound determines the amount of damage to your hearing. The American Academy of Pediatrics and the National Campaign for Hearing Health states 85 dB is the threshold for dangerous levels of noise. Sounds less than this are unlikely to cause hearing loss. However, it’s also important to think about the cumulative exposure to noise over the course of a day. To give you an idea of what 85 decibels sounds like, here are a few everyday sounds and their decibel levels:

Normal conversation: 60 dB
Vacuum cleaner: 70 dB
Restaurants: 80-96 dB
Noisy toys: 90 dB (you can look for a noise rating on the package when you buy the toy or call the manufacturer to request this information)

What about White Noise Machines?
Most of the white noise machines I came across online operated at a safe level of about 60 dB. However, we recommend checking the decibel level before buying one to be sure that it is indeed at a safe level. If you can’t find this information online, call the product manufacturer.

Benefits of White Noise for Parents
In a past post about helping parents of infants get a little more sleep, we shared results of a study suggesting that white noise can be beneficial for parents as well. Healthy sleeping newborns can be pretty noisy because they move and make noises while they sleep. Since it’s best for babies to sleep in the same room as their parents, playing some low-level white noise can help you sleep through the wiggles and soft squeals your baby makes. By keeping the white noise low-level, you will still be able to hear your baby if she needs your help.
Please let us know if you have any other questions or comments about past blog topics. We love to hear from you!

References and Resources
Chang EF, Merzenich MM. Environmental Noise Retards Auditory Cortical Development. Science. 2003; 300: 498.

The Children’s Hearing Institute:

Friday, September 16, 2011

Your Baby’s Senses (Part 4): Sight

By Jennifer Goldbronn, MAS, RD

Today, we’ll continue our series on infants' senses by sharing information about the sense of sight. First, we’ll look at some of the milestones related to visual development in the first 6 months of life and then we’ll answer 2 common questions parents have about their babies’ sight.

The First 8 Weeks

A baby’s vision begins to develop at birth and is dependent on normal function of both the neurological system and structures of the eye. Newborns can see black, white, and shades of gray and can focus well to about 8-12 inches; they can see longer distances, but they can’t control the muscles in their eyes that allow them to see distant objects clearly. Because they can only focus a short distance, much of their vision is blurred. However, practice makes perfect; babies improve their focus by first focusing on faces and then moving on to bright objects nearby. At first, newborns can focus for only a few seconds at a time, but by 8 weeks, babies can focus their eyes on their parents’ faces for longer periods.  The ability to focus is not the only thing needed for babies to see clearly. They must also develop "visual acuity," or the ability to see details. While most structures of the eyes are completely developed at birth, the visual parts of the brain are not fully developed.  Studies show that during the first month of life babies’ visual acuity is about 20/120 (The Smith-Kettlewell Eye Research Institute). What exactly does that mean? If given an eye exam (and they could read), they would be able to read the big “E” at the top of the eye exam chart only. This is about 6 times worse than a normal adult seeing 20/20.

2-4 months

By 2-3 months, babies are able to follow people or objects with their eyes, and by 4-months, babies begin to learn hand-eye coordination as they begin to reach for objects. Their ability to see details (visual acuity) improves as well; by 4 months, babies’ vision has improved to 20/60. Then, as babies learn to roll over, sit up, and pull up, eye-body coordination begins. Eye-body coordination is simply learning to control body movements within the world around them.  Babies’ peripheral vision becomes almost as good as that of adults by about 4-months old. One study using flashing lights as part of a test of peripheral vision in infants found that newborns oriented towards the flashing lights out to 30 degrees in their field of vision. As babies got older, peripheral vision improved until infants at 4-months old could see almost as far as adults do.

4-6 months

 “Two-eyed” or “binocular” vision begins by 4-5 months so that babies fuse what they see from both their right and left eyes into one image, allowing them to develop strong depth perception. By 4-5 months, babies also begin to see in full color! Imagine how exciting their world becomes. All of these visual skills continue to improve over time, and by 6-months, many babies have developed 20/20 vision as they are able to see images more sharply and in greater detail.

2 Common Questions about Infant Vision

Should I worry if my newborn is cross-eyed?
No! Young babies must learn to use their eyes together. They begin to practice this skill by following objects with their eyes as they learn how to track and use their eyes together. This takes neuromuscular control that babies must learn over time. By about 4-5 months most babies have learned to coordinate their eyes together and the crossed eyes should stop. You shouldn’t worry about a young babies being cross-eyed unless his eyes cross after 5 months of age; then you should contact an ophthalmologist.

How important is it for my baby to have black and white toys?
Many toy stores sell black and white toys, claiming that these encourage visual development of infants. While it’s true that infants prefer to look at high contrast (like black and white) images because they are the most visible to them, high contrast patterns are not the only ones babies can see. Babies can actually tell the difference between much subtler shades of gray and their sensitivity to contrast becomes 10 times better than at birth by only 9-weeks, meaning it’s almost as good as that of adults. It’s important to give babies the opportunity to see other colors (besides black and white) and their subtleties and to let them explore important objects such as your face, your hand or their own hands and feet.

References and Resources

Lewis TL, Maurer D. Multiple sensitive periods in human visual development: evidence from visually deprived children. Dev Psychobiol. 2005; 46: 163–183.

Children’s Vision Information Network:

American Optometric Association:

What Can My Baby See? The Smith-Kettlewell Eye Research Institute:

Tuesday, September 13, 2011

Your Baby's Senses: Smell

In previous posts, we've shared information about your baby's senses of hearing and taste. As we continue this series on baby's senses, we move on to babies' sense of smell.

Babies’ sense of smell, called “olfaction,” is highly developed at birth. Scientists think a baby’s ability to smell his mother is one of the important ways he learns to recognize her. Newborns spend a lot of time with their eyes closed! Researchers have found that newborns are able to tell the difference between the smell of their mothers and the smell of other women (yes, they really did a study!). Babies’ early exposure to a smell (in the first couple of hours after birth versus more than 12 hours after birth) results in a stronger and longer memory of the smell. This may be because newborn babies learn from their senses best when they have high levels of the hormone norepinephrine and this hormone is high in most babies in the first few hours after they are born.

Babies don’t have ability to know what smells are; they won’t know a flower or diaper by its smell – that takes experience. But, babies are calmed by familiar smells that they associate with good experiences (like a loving touch or breastfeeding). In contrast, babies may turn away from strangers with strong unfamiliar odors, so you might ask Aunt Mildred not to wear too much perfume when she comes to visit!

Because babies are more likely to remember the odors they were exposed to very early in life, they are more likely to be familiar with and calmed by the smell of their own mothers – since she’s right there after birth. These studies do not mean that babies won’t be able to recognize their mothers’ smell if they are not with her in the first hour or two, but it might take longer than those who are physically close to their moms earlier in life. Many studies have shown that babies who are breastfed or given their mothers’ breast milk during a painful procedure (like getting blood taken) are calmer than those who are not. Researchers think that the combination of the smell of their mothers and the sweet taste of the milk helps babies deal with the stress.

Skin-to-skin contact for about an hour immediately after birth increases babies’ recognition of the smell of their moms’ milk at 4 days postpartum. Early skin-to-skin contact has many benefits for mom and baby and many hospitals encourage the practice immediately after birth, during the best time for learning. Dads can make sure that baby is familiar with their smell by cuddling close early and often!


1. Winberg J, Porter R. Olfaction and human neonatal behavior: clinical implications. Acta Paediatr 1998; 87: 6-10.
2. Mizuno K et al. Mother-infant skin-to-skin contact after delivery results in early recognition of own mother’s milk odor. Acta Paediatr 2004; 93: 1640-5.
3. Romantshik O et al. Preliminary evidence of a sensitive period for olfactory learning by human newborns. 2007; 96: 372-376.
4. Nishitani S, Miyamura T, Tagawa M, Sumi M, Takase R, Doi H, Moriuchi H, Shinohara K. The calming effect of a maternal breast milk odor on the human newborn infant. Neurosci Res. 2009;63:66-71.
5. Shah PS, Aliwalas LI, Shah V. Breastfeeding or breast milk for procedural pain in neonates. Cochrane Database Syst Rev. 2006;3:CD004950.
6. Delaunay-El Allam M, Marlier L, Schaal B. Learning at the breast: preference formation for an artificial scent and its attraction against the odor of maternal milk. Infant Behav Dev. 2006;29(3):308-21.

Friday, September 9, 2011

Weighing the Pros and Cons of Napping (For YOU, not your baby!) Part 2.

By Jennifer Goldbronn, MAS, RD

Last time, we shared the pros and cons of napping for sleep deprived parents. In this post, we’ll share the realities of fitting a nap into your schedule and some tips to get the most out of your naps.

The Reality of Napping

In a study of napping patterns of new mothers, opportunity was significantly related to whether or not the mothers took naps. Moms who had more children and/or worked more took fewer naps (obviously!)(Cottrell 2002) Yes, it’s hard to find time to nap, and yes, you have a thousand other things to do while your child is sleeping. However, incorporating a short nap into your day may drastically improve your ability to function when your nighttime sleep is fragmented. Involve your support people in caring for your other children or taking over a few of your chores so that you have opportunities to rest or nap, especially in your baby’s first 6 weeks, or whenever your baby’s sleep patterns are especially challenging for you. If you can’t fall asleep, even resting for a short period can help you feel better. One study found that 1 hour of resting, even without sleep, improved mood (Note: this study did not include people who were recently sleep deprived). (Daiss et al.1986)

Tips for Napping

To get the most out of a "power nap," follow these tips paraphrased from sleep expert Sara C. Mednick, PhD: assistant professor of psychiatry at the University of California, San Diego.

• Keep a regular nap schedule. The best time to nap for most people is between 1 p.m. and 3 p.m.

• Don’t sleep too long. If you sleep longer than 30 minutes, you might wake up groggy.

• Try to sleep in a dark place. If you block out light by darkening the room or wearing an eye mask, you will fall asleep faster.

• Use a blanket to stay warm. Your body temperature will drop as you sleep and you don't want to lose precious nap time because you start to get cold!

As much as you may think that napping is impossible, sleep deprivation is not something to take lightly. Ask your partner to trade off with you; one of you can take a nap while the other watches the baby. Even 30 or 40 minutes of nap time can make a big difference while your baby is still young.


Cottrell L, Hildebrandt Karraker K. Correlates of nap taking in mothers of young infants. J. Sleep Res. 2002; 11: 209–212.

Milner CE, Cote KA. Benefits of napping in healthy adults: impact of nap length, time of day, age, and experience with napping. Journal of Sleep Research. 2009;18 (2):272–281.

Montgomery-Downs HE, Insana SP, Clegg-Kraynok MM, et al. Normative longitudinal maternal sleep: the first 4 postpartum months. Am J Obstet Gynecol. 2010;203:465.e1-7.

Tietzel, A. J. and Lack, L. C. The short-term benefits of brief and long naps following nocturnal sleep restriction. Sleep. 2001; 24: 293–300.

Lumley M, Roehrs T, Zorick F, Lamphere J, Roth T. The alerting effects of naps in sleep-deprived subjects. Psychophysiology. 1986; 23: 403–408.

Daiss, S. R., Bertelson, A. D. and Benjamin, L. T. Napping versus resting: effects on performance and mood. Psychophysiology. 1986;23: 82–88.

Tuesday, September 6, 2011

Happy Labor Day!

We are taking this holiday weekend to spend quality time with our families!

We hope everyone has a great weekend! We'll be back on Friday with Part 2 of the napping article.

Thursday, September 1, 2011

Weighing the Pros and Cons of Napping (For YOU, not your baby!) Part I.

By Jennifer Goldbronn, MAS, RD

A recent study of postpartum women’s sleep habits found that, after 2 weeks postpartum, less than half of mothers napped at least once per week. (Montgomery-Downs 2010) As most of our readers are aware (and have probably experienced a time or two), new parents experience significant disruptions in their sleep. (Montgomery-Downs 2010) However, more time is often spent trying to fix the baby’s sleep “problems” (which are normal waking and short sleep periods, see our sleep posts for more information about normal infant sleep) rather than finding ways to deal with the resulting (and inevitable) sleep deprivation. In a previous post we provided a few tips to help parents get a little more rest in the postpartum period and tips for dealing with sleep deprivation. Now, we would like to share the results from the research on the beneficial effects of napping for parents. We’ll look at whether or not the old adage “sleep when your baby sleeps” is truly beneficial and explain characteristics of effective naps. We’ll also describe why you sometimes feel worse after napping and how you may be able to avoid that. A study of nap-taking in mothers of young infants found that a mother’s perception of her own sleep deprivation (rather than the actual amount of sleep she got or infant awake time) determined whether or not she took a nap. However, parents may experience negative effects of sleep deprivation (like low energy and function) without even knowing it. (Cottrell 2002) Napping can help fight against some of those negative effects, so let’s explore some of the benefits of incorporating short naps into your day.

Benefits of Napping

Even for parents who generally get the sleep they need on a nightly basis, napping may lead to considerable benefits in terms of mood, alertness, and thinking. Studies have documented the benefits of naps for night shift workers including improved mood and decreased feelings of sleepiness and fatigue. Naps also improve reaction time and logical reasoning. However, not all naps are created equal; there are several factors that affect how beneficial naps are. (Milner 2009)

Factors that Affect Nap Benefits

A number of factors may influence how valuable a daytime nap will be and how restored you will feel afterwards, including how well you slept the previous night, duration and timing of your nap, and the presence (or absence) of “sleep inertia” (defined below). Other factors such as your age, gender, how often you nap, and degree of sleepiness may also influence the benefits of napping. (Milner 2009)

Timing of the Nap

During the afternoon, between about 3:00 and 5:00 pm, there is a natural circadian dip in alertness. When you nap during this time, you fall asleep faster and have less “sleep inertia” (the confusion and grogginess you might have when you wake up from a long nap) compared to naps taken in the later evening (7:00 to 9:00 pm). (Milner 2009) When Milner compared 3 similar studies, where participants took a 20-minute nap once per week at either 12:20 pm or 2:00 pm, feelings of sleepiness and self-rated performance were improved after both nap times. However, scores on objective tests were only improved following the later nap. For those who are well-rested, a later nap (following more awake time) may provide the most benefits.

Nap Duration and Sleep Deprivation

For people who are sleep deprived, it’s important to nap long enough to experience deep sleep to reduce sleepiness and improve performance. Even 30-minute naps in sleep deprived individuals contain deep sleep and improve performance. However, after a night of sleep deprivation, a 15-minute morning nap had little effect on alertness and very small amounts of deep sleep, while a 60-minute nap resulted in the highest alertness gains. (Lumley et al., 1986)

Regular Naps vs. Occasional Naps

For people who take naps only occasionally, there are several drawbacks that may prevent napping on a regular basis. Non-habitual nappers may have a more difficult time falling asleep, awaken too often, or sleep lightly; they may also sleep too deeply, experiencing greater sleep inertia after the nap than regular nappers would.

Next time: In Part 2, we'll provide some tips to help you get the most out of your napping!


Cottrell L, Hildebrandt Karraker K. Correlates of nap taking in mothers of young infants. J. Sleep Res. 2002; 11: 209–212.

Milner CE, Cote KA. Benefits of napping in healthy adults: impact of nap length, time of day, age, and experience with napping. Journal of Sleep Research. 2009;18 (2):272–281.

Montgomery-Downs HE, Insana SP, Clegg-Kraynok MM, et al. Normative longitudinal maternal sleep: the first 4 postpartum months. Am J Obstet Gynecol. 2010;203:465.e1-7.

Lumley M, Roehrs T, Zorick F, Lamphere J, Roth T. The alerting effects of naps in sleep-deprived subjects. Psychophysiology. 1986; 23: 403–408.