Are Co-Sleeping Studies Objective?
Dr. Rosemond remarked that if a co-sleeping study finds co-sleeping to be beneficial then it’s not ‘objective’. hmmmm.
Well I recieved a series of e-mails from Donna B. (thanks Donna!) who located a study that finds co-sleeping to be stressful. According to Dr. Rosemond this should be objective, huh? hmmmm. why don’t you read it for yourself!
Original Article
The sleep of co-sleeping infants when they are not co-sleeping: Evidence that co-sleeping is stressful
Melissa Hunsley, Evelyn B. Thoman *
Biobehavioral Sciences Graduate Degree Program, University of Connecticut, Storrs, CT 06269-4154
email: Evelyn B. Thoman (evethoman@mac.com)
*Correspondence to Evelyn B. Thoman, Biobehavioral Sciences Graduate Degree Program, University of Connecticut, Storrs, CT 06269-4154.
Funded by:
NICHD; Grant Number: HD32903
Keywords
co-sleeping; bed-sharing; sleep; human infants; home-monitoring; stress
Abstract
Co-sleeping proponents consider the practice to be natural and a potential protection against sudden infant death syndrome (SIDS); others consider the practice of an infant sleeping in the parents’ bed for prolonged periods at night to place an infant at risk for harm or death. For this study, co-sleeping was investigated from a different perspective, that is, as a significant early experience to investigate as it may have implications for the infant’s development. The sleep of 101 normal, full-term infants was recorded nonintrusively in the home for 24 hr periods when they were 5 weeks and 6 months old. Infants were assigned to three groups: short-term co-sleepers, long-term co-sleepers, and non-co-sleepers. Their sleep states and wakefulness were compared at the two ages and over age. At 5 weeks and 6 months, the long-term co-sleeping infants differed significantly from the non-co-sleepers on a number of measures: At 5 weeks, they showed more quiet sleep and longer bouts of quiet sleep; and at 6 months, they also showed less active sleep, fewer arousals in active sleep, and less wakefulness. Each of these differences indicates a markedly lower arousal level in the long-term co-sleeping infants. This sleep pattern has been repeatedly found to be an indicator of stress. We infer that a major source of stress for these infants is the experience of sleep disturbance documented for infants when they were co-sleeping. Based on extensive evidence for long-term effects of early stress, we conclude that co-sleeping should have significant implications for infants’ neurobehavioral development.
Received: 28 March 2001; Accepted: 25 April 2001
Donna B. sent an e-mail to the contact for the study asking for clarification:
Hello,
I found your article The sleep of co-sleeping infants when they are not co-sleeping: Evidence that co-sleeping is stressful at Wiley InterScience while looking for a different study cited in an article I read this morning. I have to admit, I think I’m a little confused, and I was hoping you could offer me either further information, or direct me to another resource.
The study compared 101 infants’ sleep patterns, and grouped the infants by the amount of time they co-slept with their parents. You made the following observation:
At 5 weeks and 6 months, the long-term co-sleeping infants differed significantly from the non-co-sleepers on a number of measures: At 5 weeks, they showed more quiet sleep and longer bouts of quiet sleep; and at 6 months, they also showed less active sleep, fewer arousals in active sleep, and less wakefulness. Each of these differences indicates a markedly lower arousal level in the long-term co-sleeping infants. This sleep pattern has been repeatedly found to be an indicator of stress.
It seems counter-intuitive to me that the lack of arousals in active sleep and less wakefulness is an indicator of stress. A great deal of effort is put forth in our society to help infants sleep through the night; and as an adult, I know I feel more rested when I sleep with less wakefulness. In my own experience co-sleeping with my child, every person in the house sleeps better, and gets more rest in general, when we share a bed.
Would you please direct me to the studies that have ‘repeatedly found [these sleep patterns] to be an indicator of stress.’
Thank you,
Donna B
and received in answer a letter that pretty much said ‘Hey, I’m glad to hear that something so stupid works for your family, but it doesn’t work for anyone else, so WHATEVER!’ and didn’t make the connection between stress and sleep at all.
So, Donna B. being quite intrepid asked Dr. James McKenna of the Mother Baby Sleep Laboratory about the study and he said it was “absurd” “incomprehensible” and “illogical” which is a good reminder why he is so cool.
Anyway, I thought you would enjoy the back and forth and I’ll keep you posted as the intrepid Donna B. researches some more!
Love,
Heather
Robyn L. Coburn said,
March 28, 2007 @ 1:55 pm
This study wasn’t published in The Onion by any chance?
If getting a good night’s sleep is an indicator of stress, then I suppose occasional insmonia is an indicator of serenity! Doublethink lives. By this logic sleep deprived new moms must be the least stressed people on the planet.
Seriously though, it sounds like they are making a correlation between infant sleep patterns and the idea that sometimes adults who are clinically depressed sleep a lot. But since it seems pretty difficult to measure clinical depression in an infant - I mean how do you assess the other symptoms as you would with an adult (eg suicidal ideation) - it becomes an assertion that is impossible to prove one way or the other.
Except by the liberal and logical application of common sense! The whole thing is a bizarre instance of cognitive dissonance.
Robyn C.
Robyn L. Coburn said,
March 30, 2007 @ 1:37 am
Well I think, maybe I have found some of the mysterious studies…although not really about deep sleep being an indicator of infant stress. I think Dr. Thoman may be referring when she says “This sleep pattern has been repeatedly found to be an indicator of stress”, to studies that show that decreased “arousability” is one of the major risk factors for SIDS - including one in Belgium in 2004 that shows that infants who have been stressed by deliberate short term sleep deprivation in which they were kept awake for up to two hours from their usual nap (ackk!) show less arousability - ie sleep more deeply after finally being allowed to nap.
I hope this link works - may need to copy and paste as I don’t know how to do that tiny url thing.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=15286256
That is for the sleep deprivation study, but if you look to the box on the right of the page there are links to other related studies about SIDS risk factors and sleep. At least one speaks of breastfeeding as a mitigating factor to environmental risk factors which is good! Also check out the one that finds that it is bad if babies sleep with a blanket over their faces. Maybe Thoman is assuming that this would happen more in a family bed.
The thing about all of these is that there is no mention of sleeping arrangements. I would guess that self arousability, in response to respiratory distress, would be more important in babies sleeping alone. And the respiratory problems are the underlying cause of the SIDS risk.
I believe there have been other studies, haven’t there Heather, that show co-sleeping to specifically reduce the risk of SIDS because of maternal awareness and the whole mother/infant dyad concept regulating breathing.
So it seems that the Thoman study is only looking at part of the picture and she is doing what so many researchers seem to do in looking at their findings - assuming the results from one population (eg crib sleepers, schooled children) apply to and, more importantly, mean the same for a completely different population (eg co-sleepers, Unschoolers).
Robyn C - indefatigable Googler.
Robyn L. Coburn said,
March 30, 2007 @ 2:36 am
OK now I’m on a roll. Here is a page discussing studies about the deep sleep response to stress and depression in infants. Scroll on down the page.
http://www.tau.ac.il/~sadeh/baby/stress.htm
Note that one of the biggest causes of stress is mother/baby separation.
I gracefully admit that apparently there are other ways to assess stress and depression in infants and withdraw my earlier comment about it being unprovable!
In none of the mentioned studies is the deep sleep a *cause* of stress as Thoman’s conclusion implied, but is seen as a response to stress - and again these are not co-sleepers (obviously if mom & baby are separated!). Are co-sleeping babies showing any other signs of unusual stress during the day - are they stressed in general? That is the next question Dr. Thoman should ask to discover if the sleep actually is an indicator of stress in the case of the co-sleepers. I’m betting that most co-sleepers in her study have really secure attachments and few are unusually stressed, and so have no corroborating symptoms. So that should lead to the conclusion that the deep sleep is neither a cause nor an indication of stress in the case of co-sleepers.
Correlation does not necessarily equal causation. That is a basic premise in scientific method.
And in any case Dr. Thoman and buddy are not very clear writers in addition to not being very forthcoming, since we are being forced to make a bunch of assumptions about what they might be meaning, and whether or not either has seen these particular studies. (I’m actually assuming Dr, is her title too!)
I’ll stop looking now.
Robyn C.
Julinda said,
April 3, 2007 @ 10:30 am
I have conducted the following experiment:
Alex, who at one time slept well in a crib, stopped doing so. Now, when he is placed in a crib or alone in bed, he wakes up and cries, or if he does remain sleep, it is for a very short period. If he is in my arms or lying by my side, he sleeps longer before waking. That is indisputable scientific proof that at this stage in his life, he sleeps better with me than alone. I am happy to oblige. With that I know all I need to navigate the night for now.
Every parent can easily replicate this experiment for accurate information as to what conditions facilitate content sleep for her/his baby. And it can be repeated as needed to account for developmental changes in the baby or environmental changes.
: )
Julinda, amateur scientist (who noticed last night, holding Alex after nursing him back to sleep, that he was the most beautiful precious little one in the whole world, as was his older brother before him)