The effects of cosleeping, according to research

Cosleeping effects on emotional health

Any amount of cosleeping at 2 months reduces risk of attachment issues at 14 months; but no additional benefit from frequent cosleeping (n=550)

We tested whether mother-infant bed-sharing is associated with increased secure infant-mother attachment, a previously unexplored association. Frequency of bed-sharing and mothers’ nighttime comforting measures at 2 months were assessed with questionnaires in 550 Caucasian mothers from a population-based cohort. Attachment security was assessed at 14 months. When using a dichotomous variable, “never bed-sharing” (solitary sleepers) versus “any bed-sharing,” the relative risk of being classified as insecurely attached for solitary-sleeping infants (vs. bed-sharers) was 1.21. In multivariate models, solitary sleeping was associated with greater odds of insecure attachment, adjusted odds ratio (OR): 1.50 and, in particular, with greater odds of resistant attachment, adjusted OR = 1.74; and with a lower attachment security score, β = -0.12. However, we found no evidence of a dose-response association between bed-sharing and secure attachment when using a trichotomous bed-sharing variable based on frequency of bed-sharing. 

https://pubmed.ncbi.nlm.nih.gov/26719041/

Cosleeping at 6 months associated with better emotional regulation at 12 months (n=193)

Information on breastfeeding and co-sleeping was collected using weekly and daily sleep diaries, respectively, for the first 6 months of life. Co-sleeping was defined as sleeping in the parents’ bed or sleeping in the parents’ room. At 12 months of age, infants were subjected to a psychological stressor. Salivary cortisol was measured prestressor and at 25, 40, and 60 min poststressor to measure reactivity and recovery. Regression analyses showed that after controlling for maternal sensitivity, infant attachment status, feeding, and sleeping arrangements at 12 months of age and other confounders, more weeks of co-sleeping predicted lower infant cortisol reactivity to the SSP. Also, more weeks of breastfeeding predicted quicker cortisol recovery. These results indicate that an early history of co-sleeping and breastfeeding contributes positively to cortisol regulation in 12-month-olds.

https://pubmed.ncbi.nlm.nih.gov/23116166/

Greater amount of cosleeping at 6 months associated with less infant temperamental intensity at 9 months (n=70)

Mother-infant dyads who experienced consistency in infant sleeping arrangements in a typical week at 6 months (i.e., habitual co-sleeping or non-co-sleeping) were characterized by more positive maternal and infant behavior and dyadic quality of interaction at 9 months compared with dyads who experienced inconsistency in sleeping arrangements. Additionally, a greater amount of co-sleeping per week was associated with an increased duration of breastfeeding, mothers working fewer hours, less infant temperamental intensity, and less maternal depression.

https://pubmed.ncbi.nlm.nih.gov/28636197/

Cosleeping associated with higher bedtime and morning cortisol levels in infants (n=82)

Eighty-two mothers and infants participated in a longitudinal study when infants were 3, 6, and 9 months old. At each time point, bedtime and nighttime parenting were recorded and infant cortisol at bedtime and the following morning was analyzed. Less co-sleeping and more maternal responses to infant distress were linked to healthier cortisol patterning. 

https://pubmed.ncbi.nlm.nih.gov/27363863/

Ever having coslept associated with lower stress hormones among young children (n=32)

In the present study, 122 cortisol samples from 32 British children aged between 3 and 8 were analyzed using multilevel modeling to assess effects of daycare attendance and other childcare-related variables on children’s stress function. Retrospective data on parent-child cosleeping showed that children who had coslept in their parent(s) room had lower cortisol levels, as did children who had attended less daycare in the first 4 years of life. 

https://pubmed.ncbi.nlm.nih.gov/17680611/

Parental presence while falling asleep at age 2 is associated with anxiety and depression at age 3 (n=4,782)

Dyssomnia and parental presence during sleep onset at 2 months and 24 months were associated with anxiety or depressive symptoms at 3 years (e.g., parental presence: odds ratio (2 months), 1.22; odds ratio (24 months), 1.58). Parasomnia, short sleep duration, and absence of set bedtime at 24 months, but not at 2 months, also preceded anxiety or depressive symptoms. These significant associations were not due to children’s anxiety or depressive symptoms at 18 months. Rhythmicity and co-sleeping were not associated with later anxiety or depressive symptoms.

https://pubmed.ncbi.nlm.nih.gov/21257976/

Cosleeping children age 2 to 13 years less likely to receive psychiatric treatment (n=86)

Cosleeping is a topic frequently of concern to parents; however, little objective evidence exists to support the historical prohibition against children sleeping in the same bed with their parents. Surveys from the parents of 86 children in the clinics of pediatrics and child psychiatry were analyzed to describe patterns of cosleeping in a group of military dependents aged 2 to 13 years. Shown is a significant increase in cosleeping with father absence and that cosleeping is less frequent in the psychiatric subpopulation.

https://pubmed.ncbi.nlm.nih.gov/1620382/

Cosleeping preschoolers are reported by parents, but not teachers, to be more intense (n=67)

67 children between 2.4-5.6 years of age from two University-affiliated preschools were studied. Parents’ ratings showed that bedsharers have less regular bedtimes; difficulty with sleep onset; more night-waking; and seek out the parents following awakening during the night. Temperamentally, bedsharers were found to be more intense and exhibit less adaptability and rhythmicity. However, teachers’ temperament ratings did not predict bedsharing and were not concordant with parental ratings.

https://pubmed.ncbi.nlm.nih.gov/11560178/

Persistent bedsharing through first six years associated with 70% higher chance of psychiatric disorder and 110% higher risk of internalizing problems  (n=4,231)

Population-based birth cohort conducted in Pelotas, Brazil. Children were enrolled at birth (n=4231) and followed-up at 3 months and at 1, 2, 4, and 6 years of age. 3583 children were analyzed. Four trajectories were identified: non bed-sharers (44.4%), early-only (36.2%), late-onset (12.0%), and persistent bed-sharers (7.4%). In the adjusted analyses persistent bed-sharers were at increased odds of presenting any psychiatric disorder (odds ratio=1.7) and internalizing problems (odds ratio=2.1), as compared to non bed-sharers. Among the early-only bed-sharers odds ratio for any psychiatric disorder was 1.4 and for internalizing problems 1.6. Limitations: Although the effect of bed-sharing was adjusted for several covariates including the family socio-economic status, maternal mental health and excessive crying, there was no information on maternal personal reasons for bed-sharing. Mothers that bed-share intentionally and those that bed-share in reaction to a child sleep problem may have a different interpretation of their children behavior that may bias the study results. Conclusion: Bed-sharing is a common practice in our setting and is associated with impaired child mental health at the age of six years.

https://pubmed.ncbi.nlm.nih.gov/27788379/

Cosleeping beyond 6 years associated with both self-sufficiency and mistrust in others in adulthood (n=219)

In this investigation, we have seen how sleeping in the same bed as the mother in infancy is associated with a higher level of protension (mistrust in others), as well as having slept during a very prolonged period of time (more than six years) in the parental bedroom. The highest scores on self-sufficiency were obtained by those who slept alone from infancy and those who slept in their parents bedroom over 6 years.

https://www.jstor.org/stable/640468

Cosleeping among school-aged children associated with less sleep and more behavioral and emotional problems (n=148)

Participants were 148 school-aged children with bedtime problems (44 cosleepers, 104 solitary sleepers) and 228 healthy peers. Results suggested that cosleepers have a significantly later bedtime, shorter nighttime sleep duration, higher Children’s Sleep Habits Questionnaire (CSHQ) bedtime resistance and sleep anxiety scores, and more behavioral and emotional problems compared to other groups. Parents of cosleepers have a significantly higher level of psychological and couple distress. A past history of sleep problems, couple and maternal distress, CSHQ bedtime resistance, sleep anxiety, and night wakings subscale scores, and nighttime fears were significantly predictive of cosleeping.

https://pubmed.ncbi.nlm.nih.gov/18443948/

Frequency of cosleeping among school-aged children associated with increasing severity of anxiety (n=113)

A total of 113 children (ages 6-12), 75 with primary generalized anxiety disorder and 38 healthy controls, participated along with their primary caregiver. A significantly greater proportion of anxious youth compared to healthy children co-slept, and greater anxiety severity was related to more frequent co-sleeping. Co-sleeping in anxious youth was associated with a delay in sleep timing and with greater sleep variability (i.e., more variable nightly sleep duration). All analyses controlled for child age, race/ethnicity, family income, and parental marital status. Co-sleeping is highly common in anxious school-aged children, with more than 1 in 3 found to co-sleep at least sometimes (2-4 times a week). Co-sleeping was even more common for youth with greater anxiety severity. Increased dependence on others to initiate and maintain sleep may contribute to poorer sleep in this population via shifted schedules and more variable sleep patterns.

https://pubmed.ncbi.nlm.nih.gov/29302831/

Cosleeping effects on behavior

Room sharing during infancy associated with higher sleep quality and prosocial behavior in middle childhood (n=193)

Current recommendations encourage parent-infant room sharing for the first 6 months of life. This longitudinal study (N = 193) is the first to examine long-term relations of early room sharing with three domains of child behavior: sleep, behavior problems, and prosocial behavior. Information on room sharing was collected daily for infants’ first 6 months. At ages 6, 7, and 8 years, outcomes were assessed with maternal and teacher questionnaires and behavioral observations. Early room sharing was not related to sleep problems or behavior problems. Additionally, more weeks of room sharing were positively related to higher maternal ratings of child sleep quality and more prosocial behavior. In conclusion, early room sharing appears to be related to positive, but not negative, behavior outcomes in middle childhood.

https://pubmed.ncbi.nlm.nih.gov/30238442/

Cosleeping among 3 year olds is associated with poor sleep but not behavior problems (n=303)

A randomly selected community sample of 303 parents of 2- and 3-year-olds were interviewed about child sleep behaviors. Most parents (55%) reported that the child slept in their bed at least occasionally and for at least part of the night, particularly during periods of minor stress or disruption of the family routine. Cosleeping was not significantly related to child behavior problems, but frequent cosleepers were more likely to report sleep problems, including difficulty getting to sleep and night waking. Children who were still cosleeping frequently 1 year after the initial assessment maintained high levels of sleep problems, compared with those who stopped cosleeping and non-cosleepers. 

https://pubmed.ncbi.nlm.nih.gov/2371094/

Cosleeping in school-aged children associated with poor sleep but not behavioral problems (n=901)

The prevalence and predictors of cosleeping were investigated in 901 healthy school-aged children. Parent reports on the Children’s Sleep Habits Questionnaire and Child Behavior Checklist were used to assess children’s sleep and behavioral problems. Regular, long-lasting cosleeping was present in 5% of our sample. Cosleepers rated higher on the Children’s Sleep Habits Questionnaire total score and Bedtime Resistance, Sleep Anxiety, Nightwakings, and Parasomnias subscales than solitary sleepers. No significant behavioral problems were found in cosleepers.

https://pubmed.ncbi.nlm.nih.gov/14767353/

Cosleeping among 3 to 8 year olds is associated with sleep disturbances but not behavioral problems (n=48)

Forty-eight mothers of children between 3 and 8 years of age completed the surveys. Overall, 48% (n = 23) of families coslept, and families with younger children coslept more than families with older children. When the families were divided into non-cosleeping (i.e., rarely) and cosleeping (i.e., sometimes and usually) groups, 100% of the cosleeping children had sleep disturbances compared to 56% of the non-cosleeping children. For mothers, 28% of the non-cosleeping mothers reported sleep disturbances, compared to 52% of the cosleeping mothers. Children’s behavioral problems were not different between the two groups. Cosleeping mothers reported lower parenting self-efficacy than non-cosleeping mothers.

https://pubmed.ncbi.nlm.nih.gov/28983997/

Cosleeping effects on sleep quality 

Cosleeping associated with inadequate sleep among young children (n=3,266)

The total sleep time among children less than 48 months of age in Shanghai was less than that among children the same age in Western countries. The factors related to children’s inadequacy of total time included parental insufficient sleep time, children’s difficult temperament parental presence at sleep onset of children, and cosleeping.

https://pubmed.ncbi.nlm.nih.gov/12126541/

Cosleeping associated with sleep disturbances among children (n=1,600)

Totally 1,600 children aged 2-12 years old were selected and investigated by using questionnaire. Results: The proportion of the prevalence of sleep disturbance was 37.88%. There were significant differences shown in different sexes and ages, and in incidence of symptoms of some sleep disturbances. The affecting factors were the co-sleeping, tonsillitis, bronchitis, pollen allergy and their parent’s snore.

https://pubmed.ncbi.nlm.nih.gov/16329801/

Other effects of cosleeping

Cosleeping in early childhood slightly increases cognitive ability at 6 years; no benefit seen at 18 years (n=205)

We report results of the first longitudinal study of outcome correlates of parent-child bedsharing. Two hundred five families in nonconventional and conventional family lifestyles have been followed since 1975. A target child in each family was followed from the third trimester of mother’s pregnancy through age 18 years. Bedsharing in early childhood was found to be significantly associated with increased cognitive competence measured at age 6 years, but the effect size was small. At age 6 years, bedsharing in infancy and early childhood was not associated with sleep problems, sexual pathology, or any other problematic consequences. At age 18 years, bedsharing in infancy and childhood was unrelated to pathology or problematic consequences, nor was it related to beneficial consequences. 

https://pubmed.ncbi.nlm.nih.gov/12177571/

2 to 6 year olds who cosleep every night are less likely to be overweight than those who rarely do (n=635)

Cross-sectional data from the ‘Healthy Start’ study including 635 2- to 6-year-old Danish children, who were all considered obesity prone.  Analyses were adjusted for the child’s age and gender, overall family stress, parental educational level, and parental BMI. There was a tendency that the odds ratio of being overweight was lower with increasing frequency of joining parents’ bed. Indeed, compared to children who joined their parents’ bed every night, children who rarely joined were almost three times more likely to be overweight, also after adjusting for confounders (odds ratio 2.74). 

https://pubmed.ncbi.nlm.nih.gov/30308484/

Bedsharing in late childhood associated with 12 times the likelihood of bedtime resistance  (n=1452)

Participants were 1452 early adolescents from 10 primary schools in Shanghai, China. The median of age was 10.83 years. The prevalence of bed-sharing was 16.8%. Positive parental attitude toward bed-sharing (OR: 9.87), asthma (OR: 2.15), smaller residential space (OR: 1.90), extended family (OR: 1.59), and being physically less mature (OR: 2.39) increased the likelihood of bed-sharing. Bed-sharers were more likely to have bedtime resistance (OR: 12.20), sleep anxiety (OR: 3.76), and poor sleep quality (OR: 3.21) compared to non-bed-sharers. Furthermore, bed-sharing was associated with daytime sleepiness (OR: 1.53) but not with sleep duration.

https://pubmed.ncbi.nlm.nih.gov/26847978/

Cosleeping effects on parents

Among mothers of toddlers with sleep problems, those cosleeping get 51 less minutes of sleep per night, increasing risk of depression (n=280)

Perceived toddler sleep problems were associated with an average decrease of 51 minutes in maternal sleep when co-sleeping (mean = 6.1 h). Maternal sleep duration mediated the relation between perceived toddler sleep problems and maternal symptoms of depression, anxiety, and stress for co-sleeping mothers. Maternal sleep duration did not mediate relations between maternal mental health symptoms and perceived toddler sleep problems.

https://pubmed.ncbi.nlm.nih.gov/29570568/

Cosleeping beyond the first 6 months associated with increased marital stress and sleep disruption in mothers (n=139)

Patterns of infant sleep arrangements across the infants’ first year were derived from information obtained from 139 families at 1, 3, 6, 9, and 12 months of infant age. Compared with families whose infants were solitary sleepers by 6 months, persistent cosleeping was associated with sleep disruption in mothers but not in infants, although mothers in persistent cosleeping arrangements reported that their infants had more frequent night awakenings. Persistent cosleeping was also associated with mother reports of marital and coparenting distress, and lower maternal emotional availability with infants at bedtime (from home observations). Persistent cosleeping appeared to be a marker of, though not necessarily a cause of, heightened family stress, although the present design did not enable strong tests of causal processes, and results may be particular to cultures that are not supportive of cosleeping.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4959950/