Sleep disturbances and changes in circadian rhythms are commonly observed in pregnant women. These disorders can result from anatomical, physiological, psychological, and hormonal alterations that can influence sleeping during this phase. Sleep disorders during pregnancy can be responsible for detrimental effects on both mother and foetus. In this chapter we will focus on the epidemiology of sleep disorders, physiological sleep mechanisms and their alterations during pregnancy, as well as on risk factors for sleep disorders in pregnancy. We will then focus of the most frequent sleep disorders during pregnancy, also considering eventual adverse implications for both mother and child, prognosis, and possible pharmacological and non-pharmacological treatments.