Anne had a baby about 10 months ago. Ever since, she has a poor appetite, been unable to sleep (even when the baby wasn't waking her), poor self-esteem, and has been unable to concentrate for any length of time. She is most likely suffering from.

1) postpartum blues
2) postpartum psychoses
3) cyclothymic disorder
4) postpartum depression

Postpartum depression is a mental state of women after giving birth to their babies. In such conditions, physical health, emotional health, and, behavior of the mother is affected.

After giving birth, a mother goes through 'baby blues' that lasts for 3 to 5 days after giving birth to the baby. Postpartum depression is a severe condition in a mother. If baby blues do not go away after 3 to 5 days and conditions last for more than 2 weeks, it reaches the postpartum depression stage.

The symptoms of postpartum depression include loss of pleasure, poor self-esteem or feelings of worthlessness, lack of sleep, etc.

In the given case, Anne is suffering from postpartum depression as she has symptoms of it. That is a lack of sleep, poor self-esteem, lack of concentration, etc.

So, the correct answer is option 4.