Sleep: A missing component of postnatal distress?

Pregnancy and the postpartum period are usually characterized by deep alterations in sleep. The complex interaction of bodily changes, breastfeeding practices, and the random wake-sleep patterns of newborn babies promote significant sleep disruption and deprivation in women at this stage.

In a review of the main findings about sleep, pregnancy, and the postpartum period, Lee (1998) asserts that the main variables underlying sleep alteration are hormonal changes, physical symptoms, and infant sleep.

With regard to hormonal alterations, it has been argued that the high progesterone levels that are essential to the pregnancy process affects drowsiness and are responsible for the increased sleepiness and earlier sleep onset during the first trimester of pregnancy. Additionally, it has been argued that progesterone has an inhibitory effect on smooth muscles, which is related to increased urinary frequency at this early stage (Lee, 1998).

From a different perspective, physical symptoms during pregnancy have been widely acknowledged as a disturbing factor (Kamysheva et al, 2010). The most common somatic complaints during this stage include:
- nausea, vomiting
- heartburn and other discomforts associated to eating
- increased urination
- tender breast
- headache
- vaginal discharge
- shortness of breath, and
- backache

Finally, infant sleep has been pointed out as a significant factor underlying sleep disruption during the postpartum period due to the random sleep-wake patterns that are commonly observed in newborn babies, breastfeeding practices, and baby’s temperament (Dennis & Ross, 2005; Hiscock & Wave, 2001; Horiuchi & Nishihara, 1999; Meltzer & Mindell, 2007).

Interestingly, research has pointed out an association between sleep and mood, and has provided significant evidence to support the bidirectional influence between sleep alteration and depression (Breslau et al, 1996; Kahn-Greene et al, 2007).
In line with this argument, some evidence supporting the significant association between sleep and depressed mood during pregnancy (Jomeen & Martin, 2007; Skouteris et al, 2008) and the postpartum (Goyal, Gay and Lee, 2007) has been reported. Therefore it has been suggested that poor sleep quality might increase the vulnerability to PPD (Okun, Hanusa & Hall, 2009).