Depression is definitely a possibility.
It sounds like you’ve been under a lot of stress for a very long time. As such your need for sleep may be due to adrenal fatigue or even a Vitamin D defficiency.
I’ve also found that when a significant amount of stress is lifted, for whatever reason, my body responds with a need for greater sleep. Why? I think it’s because my body needs to repair itself and sleep in one way of doing that. Since I have a few on-going high stressors I set aside 1 day each week when I allow myself to crash. I stay up the night before as long as I want. I sleep in that morning as long as I want. Then I do whatever I feel like doing after; listening to my body for what it needs. Sometimes I stay in and binge read. Sometimes I get antsy, so I go hike or work in my yard. I do not, under any circumstances, do anything work related. I’ve practiced this for so long, I know when my day of rest hasn’t been restful enough (ie when on vacation or if there’s an event that day I want to attend) and, generally, have to make up that time to feel well again.