Postpartum period
During the subacute postpartum period, psychological disorders may emerge. Among these are postpartum depression, posttraumatic stress disorder, and in rare cases, puerperal psychosis. Postpartum mental illness can affect both mothers and fathers, and is not uncommon. Early detection and adequate treatment is required. Approximately 25% – 85% of postpartum women will experience the "blues" for a few days. Between 7% and 17% may experience clinical depression, with a higher risk among those women with a history of clinical depression. Prevalence of PTSD following normal childbirth (excluding stillbirth or major complications) is estimated to be between 2.8 and 5.6% at 6 weeks postpartum.
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.