Pregnant women experience a greater degree of sleep disturbance than their non-pregnant counterparts. Complaints range from sleep maintenance issues to excessive daytime sleepiness. Emerging evidence suggests that there is variability in sleep patterns and complaints which manifest differently among pregnant women. Moreover, it is well accepted that sleep disturbance can dysregulate normal immune and endocrine processes that are critically important to the health and progression of gestation. A possible consequence of sleep disturbance is an increased risk for adverse pregnancy outcomes. Then again, many endogenous and exogenous factors, including pregnancy-related physiological, hormonal, and anatomic changes, as well as lifestyle changes, can impact the degree and chronicity of sleep disturbance. Alas, there is still much to learn in terms of what women can/should expect with regard to the timing, degree, frequency, and/or severity of a specific pregnancy-related sleep disturbance(s), despite the number of published studies evaluating what sleep during pregnancy encompasses.