Background: It is unclear whether subjective or objective measures of sleep during pregnancy are more pertinent to pregnancy outcomes. Moreover, it is unclear as to whether subjective indices (i.e., those likely influenced by psychological thoughts and emotions) are more likely than objective measures to modify inflammatory cytokines.
Method: Subjective and objective measures of sleep were collected from 166 pregnant women. Sleep data, both aggregate and variability measures, from diary and actigraphy, were ascertained for three 2-week periods during early gestation (10-20 weeks). A fasting morning blood sample was assayed for the cytokines (IL-6, IFN-γ, and TNF-α). Sleep, stress, and depression questionnaires were also collected. Repeated measures ANOVAs, regression models, and independent t tests were used to analyze the data.
Results: Diary-assessed total sleep time (p < .05) and actigraphy-assessed sleep latency (p = .05) were negatively associated with gestational age. Variability in actigraphy-assessed sleep latency (p < .01) was negatively associated with infant weight. None of the cytokines was associated with any of the outcomes. t tests revealed that those with a complication were older (p < .05) and had higher pre-pregnancy BMI (p < .05), higher self-reported stress (p < .05), and lower IFN-γ (p < .05).
Conclusion: Findings suggest that longer and more variable sleep latency, as well as shorter sleep duration, is associated with shorter gestational age or a lower birth weight infant. Overall, the findings suggest that among a low-risk, healthy sample of pregnant women, sleep disturbance does not pose a substantial risk for adverse delivery outcomes.
Keywords: Cytokine; Gestational age; Inflammation; Pregnancy; Sleep; Stress.