Absolutely. I think for me it has been a combination of fluctuating hormones (progesterone, I've read, has a sedating effect) and just feeling like crap. I've been too nauseous and tired to do things I normally like to do or see friends or do much of anything really, and I think that would make anybody feel sad. Food is also so important, I think, to the human experience of joy and community and connection with the ground, and when you can't enjoy it, life as a whole becomes a lot more difficult to enjoy. My motivation is completely sapped and even at work, when I *have* to do things, I do them slowly and with as little creativity and energy as necessary just to get by. Which is not how I normally approach my job.
I've been depressed before, and this is not it. When I was depressed it was like a heavy fog that I couldn't get out of and eventually didn't even want out of because I'd forgotten how to feel any other way. This, on the other hand, is so purely dependent on hormonal shifts and symptoms that it's almost embarrassing. For a while, when my symptoms were at their worst and most constant, it was kind of similar. But now, at the back end of my first trimester, it feels different. On a good symptom day (which I'm having more and more of at this point, thank goodness), I feel like I have "juice" again. I feel genuine happiness, I can get excited about the baby, I can think of things to do and foods to eat, I want to snuggle and laugh with my husband, I want to go outside and move more, and I feel like myself. Even the flowers in my garden look bright again. But when a wave of symptoms shows up, my mood plunges and I feel sad and lethargic and forget what I like to do. Sometimes that lasts for days, depending on how long the nausea and fatigue stay with me. Then they go away and I feel like myself again. There's this phenomenon called "sickness behavior" that humans exhibit when ill, to keep them from expending too much energy and to alert others to their needs and engender help. Depressive behavior is a key part of that, and I think it's what happens to at least some of us when a wave of symptoms hits. I think that's normal, even though it totally sucks.
I'm pointing out the difference because there is such a thing as prenatal depression, so if you find that you can never get on top of it and can't catch glimpses of your normal self in there, even when your body is feeling OK, you might ask your doctor about it. If you're not comfortable with drugs, talk therapy can be just as effective.
How far along are you? My saddest time was probably between 7 and 9 weeks, when my symptoms were the most relentless. I'm 11+ weeks now, and the waves don't hit as often anymore.
It's really hard. People had to keep reminding me that the first trimester wouldn't last forever, that pregnancy wouldn't last forever. In the depths of despair it really feels like it will. The important this is that you keep posting, keep being honest, and keep sharing your feelings with others. It helps not to hold it all inside.
We'll be holding you in our thoughts for sure. Please keep posting!