Significant “emotional” swings are quite commonly encountered after all types of elective surgery. The specific cause of the "postoperative depression" is not known; in my opinion, it is probably multifactorial ( factors such as stress, pain, unanticipated length of recovery, being away from usually enjoyed activities/people…).
In my experience, patients who have a history of depression may be more prone to such emotional “ups and downs”. In other words, patient personality features ( "glass half full") makes a difference when it comes to the recovery experience.
I suggest that patients do their best to occupy your mind with activities that they enjoy. For example, for our patients experiencing these types of post operative “sadness”, I suggest they walk outdoors (fresh air), see movies, read books they enjoy, seek family/friends' support…
You may find the attached link, discussing the occurrence of "emotional ups and downs" helpful to you.
Many patients go through a down period after any cosmetic surgery. One has to do with the fact that the area treated is swollen, misshapen, painful and not what they expected. Maybe this is due to the plastic surgeon not preparing the patient well enough. I spend a lot of time in my pre-operative visit telling and explaining this to the patient. The other factor is that they are taking pain meds which are downers like codiene which I encourage them to get off. Fortunately, as you experienced, this is a transient process.
Thank you for your question regarding the emotional impact of breast augmentation. With elective cosmetic surgery, including breast surgery, there is a combination of expectations, stress, and the emotional effects of swelling/brusing/discomfort which play a role. Some people are more likely, based on their personalities, to experience ups and downs emotionally with any stressor. Add to this the effects of pain medication after surgery which can cloud the emotions as well! Other patients change their expectations after surgery, or do not see what they actually look like with the eyes of others who see them. This is a complex, multifactorial problem which covers the spectrum of psychology, emotions, support systems, etc. Good question!