Research: Postnatal sleep - a pilot study

Background

Postnatal depression (PND) has a negative impact on the child, including poor attachment, and may lead to emotional and cognitive development. Important changes to sleep are seen during the postnatal period, and not just related to being woken by the baby. Objective measures of sleep have been seen to be poorer for postnatal mothers, compared to non-postnatal women, and tend to be poorer in the earlier postnatal stages. Depression is more likely to occur in those early stages. Despite that evidence, very little has been explored about the specific relationship between poor sleep and depression during the postnatal period. Those studies that have been conducted have tended to focus on either objective or subjective factors of sleep; none have explored both at the same time. Furthermore, few studies control for prior existing depression. We sought to address these factors and have undertaken one pilot study (discussed below).

What we did

We examined 21 women, 7 with a history of major depressive disorder, 14 with no such history. Measures were taken in the first week after the birth of their baby, and again at weeks 3 and 5. None of the mothers presented obstetric complications or problems with the infant that lead to hospitalisation of the mother. No mothers were currently depressed (confirmed by clinical diagnoses). Objective measures of sleep were taken with actigraphs. Subjective reports of sleep were examined via the Pittsburgh Sleep Diary (PghSD; Monk et al, 1994). Current mood was measured via the Edinburgh Post Natal Depression Scale (EPDS; Cox et al, 1987). Current fatigue was determined using the Multidimensional Assessment of Fatigue Scale (MAF; Belza, 1995). We found a strong negative correlation between sleep efficiency at week 1 vs. EPDS score at weeks 3 and 5 (sleep efficiency = total sleep time ÷ time in bed), but no relationship with EPDS week 1 measures. A Mixed 2x2 ANOVA indicated that sleep efficiency improved from week 1 to 5, and that sleep efficiency was poorer for women with a history of depression. Also, EPDS scores became poorer between weeks 1 and 5, more so for women with a history of depression. These results reinforce evidence regarding the strength of relationship between poor postnatal sleep and mood, particularly for those women likely to vulnerable for depression.