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Is poor sleep a risk factor for postanal depression?
Around 35-80% of women experience some form of ‘baby blues’ in the first week to ten days after childbirth. However, around 10-15% proceed to develop the more serious condition of postnatal depression (PND; a form of depression after a women gives birth). Identified risk factors have included poor partner relationship, low social support, and previous history of depression. Whether poor sleep is a significant risk factor for PND has received little attention, even though sleep disturbances are common during pregnancy and the postnatal period. The study will investigate whether there is a relationship between disrupted sleep and mood in women during pregnancy and the postnatal period. A three-stage longitudinal design will be conducted in which women will be assessed for sleep, fatigue and mood during the third trimester of pregnancy and at weeks 1 and 12 after birth. Participants will include 40 healthy women: 20 with a history of depression; and 20 without. Sleep diaries will measure subjective sleep, while additional scales will examine fatigue, mood and depressive symptom; demographic questionnaires will be used to control for other risk factors for PND. Objective measures of sleep will be conducted using electroencephalography (EEG; several electrodes are fitted to the scalp and face in order to measure brain activity, eye movements and muscle activity, providing information about different stages of sleep). It is predicted that poor sleep during late pregnancy and the early postnatal period (particularly subjective sleep quality) will be associated with poorer mood in the postnatal period. This relationship is predicted to be stronger in women with a history of depression.
Sleep satisfaction in depression
Background: Much of previous research has focused on objective measures of sleep and how they illustrate disturbed sleep in mental illness, particularly depression. Typically this has been undertaken with sleep EEG, which has shown that depressed individuals take longer to get to sleep, wake more often throughout the night (and for longer periods), wake earlier than desired, and generally sleep less than those not depressed. These studies also show that rapid-eye movement (REM) sleep is affected; depressed people tend to enter REM sleep earlier during the sleep episode, and spend more time in REM sleep throughout the night. However, in my PhD, I felt that subjective factors had been overlooked. This work was undertaken in collaboration with Professor David Baldwin (University of Southampton), Dr Hannie van Hooff (Vrije Universiteit), Dr Christine Campbell (St Mary's University College, Twickenham), and Emma Grabau.
What we did: We explored the relationship between sleep and depression (and more recently anxiety) across three empirical studies and two reviews. The state of research regarding the relationship between sleep and depression was reported in our review Mayers & Baldwin, 2006. The effect that antidepressants have on sleep may also be a factor in this relationship. Some antidepressants appear to promote sleep, while others have been observed to disrupt sleep. We explored this in our review Mayers & Baldwin, 2005. Published in Human Psychopharmacology, this was one of the most accessed articles from the Journal for that year. It has been cited over 50 times, according to ISI Web of Science data (more than 100 times according to Google Scholar).
Subjective perceptions of sleep satisfaction were compared to perceived sleep timing in a series of studies focusing on depressed patients, healthy controls, and first-degree relatives. In the first study Mayers, van Hooff & Baldwin (2003a), 20 depressed patients were compared to 20 healthy controls. We found that the depressed group reported significantly poorer sleep satisfaction than controls, even though they did not differ from controls on sleep timing perceptions. Our second study replicated these findings, but also explored whether sleep perceptions in depression were expressed in a similar way by the nearest relatives. We found that the immediate relatives of depressed patients reported sleep in much the same way as the depressed individual, while there were no such similarities between the healthy controls and their relatives. Furthermore, reports of poor sleep by the relatives of depressed patients were associated with reports of poorer mood, while poorer sleep perceptions in the control group (and their relatives) were more likely to be related to feelings of weariness. Further details about this study can be found in Mayers, van Hooff & Baldwin (2003b). In our third study, we specifically differentiated perceptions of sleep timing and sleep satisfaction in relation to reports of anxiety and depression, using samples drawn from Depression Alliance UK(n = 46) and university students (n = 52). Using independent one-way ANOVAs and multiple regression, we found that variance in sleep timing perceptions were more likely to be associated with anxiety, than depression. Meanwhile, variance in perceptions of sleep satisfaction was more likely to be explained by depressive symptoms. Further details about this study can be found in Mayers, Grabau, Campbell & Baldwin (2009).
- 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); we plan to extend this work further.
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, a watch-sized device that is strapped to the wrist or ankle. These reliably detect the amount of time spent asleep vs. waking states. 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. |
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