How exactly are you falling asleep? Do you mean your sleeping patters are messed up? With depression the sleep symptoms are either you sleep too much for long periods or you barely sleep at all or your sleep is irregular like staying up all night and sleeping during the day which is what I have.
I have asked my doctor am on a few antidepressants and one antianxiety pill then I have a pain pump as well for chronic pain. I fall asleep like this every day now for the last at least six months or longer and I am getting very concerned!! Sometimes meds will cover up and not show all the true answers of blood work!!!?? This is where I am still very confused!! Holly
I used webmd.com - Symptom Checker to see what conditions would cause your symptoms and these conditions were at the top of the list :
Depression (Adult), Premenstrual Syndrome, Insomnia, Depression (Postpartum), and Fibromyalgia.
In my opinion I'm thinking maybe your anemic (that's when your body doesn't have enough red blood cells which are important for carrying oxygen & nutrients through the body), but then again I'm not a doctor. I'll put the link to webmd's symptom checker and you can try it yourself. If your still concerned then you should check in with your doctor, he/she will be able to assess your symptoms.
webmd.com symptom checker : http://symptoms.webmd.com/#/introView
may be something bite you and gave you poison that made you to sleep