An Examination of Changes in Emotion Co-Regulation Among Mother and Child Dyads During the Strange Situation.

The present study applied State Space Grid analysis to describe how preschooler-mother dyads co-regulate emotion in the Strange Situation. Second-to-second mother and child affect during pre-separation play (baseline) and the final reunion (post perturbation) episodes of the Strange Situation were coded for 80 dyads. Change in emotion co-regulation across the two Strange Situation episodes was examined with linear mixed models for groups with secure and insecure classifications. The groups did not differ at baseline. Change in content-specific emotion co-regulation but not content-free emotion co-regulation was found to be significantly different within and between groups. Both secure and insecure dyads reduced the time spent in positive interaction but increased the time in negative interaction across two episodes; the change in secure dyads was less pronounced than in the insecure dyads. After the separation, secure dyads had more positive interactions and fewer negative interactions compared to insecure dyads. Results highlight how secure dyads adapted to the stressful change, whereas insecure dyads were more reactive and less resilient to the stress of the study's brief imposed separation.

Light is beneficial for infant circadian entrainment: an actigraphic study.

AIM: This article is a report of an exploratory study of the relation between light exposure and circadian rest-activity patterns in infants. BACKGROUND: Ambient light is a major environmental stimulus for regulation of circadian rhythm of sleep and wake in adults, but few studies have been conducted to examine environmental light exposure in relation to rest-activity circadian rhythm parameters of infants. METHODS: An intensive within-subject design was used with a convenience sample of 22 infants (mean postnatal age 49·8 days) who wore a combined light and activity monitoring device for seven consecutive days at home. For each infant, light data (lux) were aggregated over the 7 days into categories of illumination and expressed in mean minutes/day. Circadian light and activity parameters, including mesor, amplitude, acrophase and R(2) cosinor fit, were determined using cosinor analysis. Associations between light exposure and circadian rest-activity rhythm parameters were examined using correlation and regression analyses. Data were collected between 2006 and 2007. RESULTS: Infants spent only one-eighth of their daytime hours in an environment with >100 lux light level. There was a relatively large statistically significant relation between the acrophase of light exposure and the acrophase of activity. Increased duration of daily exposure to >100 lux of illumination, and increased amplitude of circadian rhythm of light were associated with stronger circadian patterns of infant activity. CONCLUSION: Results suggest an association between light and activity patterns and that increasing duration of exposure to moderate light levels may be a simple and economical nursing intervention during the early postnatal weeks.

Mother-infant activity synchrony as a correlate of the emergence of circadian rhythm.

OBJECTIVE: Entrainment to the day-night cycle is critical for infant sleep and social development. Synchronization of infant circadian systems with the social 24-hr day may require maternal activity signals as an entraining cue. This descriptive and exploratory research examines the activity level and circadian pattern in mothers and infants. METHOD: Twenty-two healthy mothers and their infants (postnatal age 49.8 ± 17.1 days) wore actigraph monitors for seven days. Daytime (06:00-21:59) and nighttime (22:00-05:59) activity levels and circadian parameters of rest-activity patterns (i.e., mesor, amplitude, acrophase, and 24-hr cosinor fit) were calculated. RESULTS: Mothers and infants were significantly more active during the day than at night. The goodness-of-fit index for the model (R2) indicates that circadian rhythm accounted for a mean of 29 ± 10% and 12 ± 8% of the variability in maternal and infant activity, respectively. Acrophase of activity occurred at 15:46 ± 1:07 for the mothers and 15:20 ± 1:21 for the infants. The mean within-dyad correlation of activity counts was r = .46 ± .11, and the within-dyad correlation was associated with the amplitude (r = .66, p < .01) and 24-hr cosinor fit of infant activity (r = .67, p < .01). CONCLUSIONS: Our findings suggest maternal rhythms as a possible exogenous influence on shaping an infant's emerging rhythms and synchronizing them with the external light-dark cycle. Strong pattern synchrony between maternal and infant activity may support infant circadian entrainment and enhance a regular 24-hr sleep-wake schedule during the early postnatal weeks.

Twenty-four hours light exposure experiences in postpartum women and their 2-10-week-old infants: an intensive within-subject design pilot study.

BACKGROUND: Adequate light exposure is critical for entraining circadian rhythms, regulating sleep-wake cycles, and maintaining optimal mood. Yet, few studies have reported normative data on light exposure experiences in postpartum women and young infants; none has examined the two simultaneously. OBJECTIVES: The objective of this pilot study was to document the 24-h light exposure experiences in postpartum women and their infants. DESIGN: An intensive within-subject design was employed. SETTINGS: The participant's natural home environment. PARTICIPANTS: Twenty-four healthy mother-infant pairs were recruited from the general community in Seattle, USA. Two mother-infant pairs did not have complete data, resulting in a final sample size of 22 (12 female infants). METHODS: Mothers and infants wore a monitor to continuously record illumination levels for 7 days. Data were aggregated within subject to calculate summary measures of illumination exposure. Circadian patterns of light were examined using cosinor analysis. Pearson correlation was used to examine the relation between maternal and infant light exposure. RESULTS: Mothers spent 71.13 +/- 11.58% and infants spent 80.07 +/- 8.27% of their daytime hours (defined as 06:00-21:59) in an illumination level <50 lux. Mean minutes >1000 lux per day was 54 +/- 39 for mothers and 23 +/- 18 for infants. Maternal and infant light exposure exhibited a modest circadian pattern and a strong correlation, both in the timing of peak illumination exposure (r = 0.93, p < 0.01) and in the level of light exposure (r = 0.7 0 +/- 0.07). CONCLUSIONS: Postpartum women and infants experience low ambient light levels with short periods of bright light during the day. Whether this level of light is sufficient for optimal postpartum mood and infant circadian entrainment warrants further investigation. If higher levels of light were indeed necessary for postpartum women and young infants, increasing ambient light levels through the use of natural sunlight (i.e., walking outdoors) could be a simple and economic nursing intervention. The strong pattern synchrony between maternal and infant light exposure suggests that mothers play the primary role in providing a lighting environment suitable for infants to synchronize their circadian rhythms to a 24-h day.

Dysregulation of the hypothalamic-pituitary-adrenal axis in postpartum depression.

Postpartum depression (PPD) affects at least 10% to 15% of postpartum women, including more than 600,000 American mothers in 2003 alone. Dramatic changes in the hypothalamic-pituitary-adrenal (HPA) system in the transition from pregnancy to postpartum coupled with research on the psychobiology of depression provided the foundation for this study. The purpose of this study was to compare the reactivity and regulation of the HPA axis components, adrenocorticotropic hormone (ACTH) and cortisol, in depressed and nondepressed postpartum women. A comparative, longitudinal study design was used with 22 normal, healthy, nondepressed pregnant women. Physiologic and postpartum depression data were collected at 6 and 12 weeks postpartum at a university clinical research center. Maximal treadmill exercise stimulated plasma ACTH and serum cortisol levels which were measured before, during, and after 20 min of exercise. Postpartum depression was measured with the Postpartum Depression Screening Scale. Lag within-subject ACTH levels predicting cortisol regression slopes were significantly different between the depressed and nondepressed groups at both 6 and 12 weeks. The depressed group showed no relationship between their ACTH and cortisol levels, with higher ACTH and lower cortisol levels when compared with the nondepressed group. The expected regulated relationship with cortisol levels rising in response to rising ACTH levels was found in the non-depressed group. These findings indicate that the HPA axis was dysregulated in the depressed group, but regulated in the nondepressed group at 6 and 12 weeks postpartum. This pattern of higher ACTH levels to stimulate less cortisol is similar to patterns found in women with early life stresses.