If ever notice when your human sighs? Or seems to stop moving? I’ve seen that with my girl. I would tap her to make sure she was still alive. She always responded when I did so. But still I wondered if she was depressed.
Sometimes when humans are depressed they won’t get up out of bed. They don’t need to sleep off and on all day as we do, so it’s a bad sign. If they forget to eat or feed you, it’s time to do an intervention.
Humans do get depressed and they need us cats to help them get through it. I would suggest give them a head butt and rub up against them. Cuddle up against them and purr as loud as you can. It’s a simple and easy way to let them know you still care.
I’ve done that with my girl and she always got better. It wasn’t always so safe to sleep next to her as she is a restless sleeper, but I do like to sleep with her. It was better when she slept in bigger beds. Then I would have a safe place to sleep near her without having to worry about her crushing me by accident.
I hope these tips help if you human gets depressed. Talking to them might help to. I think they need to socialize as we cats do too.