This article discusses the recent finding that infants born to mothers with depression exhibit sleep difficulties as soon as two weeks after birth. This finding, though preliminary (this initial research only had 18 subjects) is important, in that early sleep difficulties are associated with the later development of early-onset depression. From the article:
Results indicate that infants born to mothers with depression had significant sleep disturbances compared to low-risk infants; the high-risk group had an hour longer nocturnal sleep latency, shorter sleep episodes and lower sleep efficiency than infants who were born to mothers without depression. Although average sleep time in a 24 hours did not differ by risk group at eight two or four weeks, nocturnal total sleep time was 97 minutes longer in the low-risk group at both recording periods. High-risk infants also had significantly more daytime sleep episodes of a shorter average duration.
The article also discusses the potential reversibility of these sleep difficulties as a way of potentially reducing or eliminating the later development of depression. I've posted several articles regarding the importance of sleep, and the assocation of sleep problems with other issues, and it is no surprise that sleep problems at infancy is associated with later mood difficulties. Hopefully further research will allow for early detection and intervention.