Hi M.,
It sounds like you're very busy. A working mom with three children.....How can you NOT be? Are you able to take any time out for yourself? How about just time to get out of the house, read a book, go to the park, or shut your eyes and listen to music? If you're smirking right now about how ridiculous theses ideas are, then maybe YOU NEED THEM!
Wanting to sleep all day is a symptom of depression, but there are also others. It all depends upon the person, and how your wanting to sleep all the time is affecting other areas of your life. Feeling exhausted is no fun, especially with a family that you love (and only two hands...haha). My advice is to take care of yourself, and look into counseling if you find that you feel sad more days than not. If you're feeling helpless, have little hope that things will improve, and are having trouble functioning at work, then maybe you need professional help. And, if you're feeling so low that you don't think you can go on anymore, please seek help immediately. I hope you have family & friends that are very supportive.
Remember that you're doing a fantastic job with your kids, and keep in mind that you have to take good care of yourself in order to take good care of them. Without you, they would be lost. So, don't beat yourself up....Life can be tough sometimes. Honestly, my hat is off to you! That said, you could have a medical condition that is causing your fatigue. Get it ruled out, and then try to fit in some "me time."
Hope this helps. Have a great night!