Maternity blues
Maternity blues, also known as baby blues and postpartum blues, is a transient condition that 75-80% of mothers could experience shortly after childbirth with a wide variety of symptoms which generally involve mood lability, tearfulness, and some mild anxiety and depressive symptoms. Baby blues is not postpartum depression, unless it is abnormally severe.After the placenta is delivered, the placental "hormone factory" shuts down causing radical changes in hormone levels, and the woman can suffer symptoms due to withdrawal from the high pregnancy levels of estrogen, progesterone and endorphins. Combined with this shift in hormone levels is the physical, mental and emotional exhaustion - as well as sleep deprivation typical of parenting a newborn. All of these factors contribute to the condition.
Psychological stress and sleep
Chronic maternal stress in pregnancy exposes the foetus to increased levels of glucocorticoid and inflammatory markers which in turn negatively effects the H-P-A axis and disrupts sleep regulation of the foetus. Up until the age of 2 years, children who have been exposed to pre-natal stress have shortened and disorganized sleeping patterns. During early childhood development the child's brain is particularity sensitive to adverse events such as family conflict, maternal post-natal depression or abuse. It is thought that it is via sensitization of the H-P-A axis that an abnormal stress response is developed in response to these events/ stressors which in turn causes emotional disorders and later life sleeping disorders. 
Observations have been made that there is an association between stress, sleep and Interleukin-6 proposing a possible mechanism for sleep changes.