Weird behavior keeping my up at night

Hi - I just joined this community because I have an issue I've never experienced before and would like some insight. 

I've had cats most of my life, along with dogs, horses and other animals. Today, I have three cats, all rescues. I also have two dogs, a German Shepherd and a three-legged Pit BUll. The dogs and cats get along wonderfully. About a year ago, a friend asked me to take in a cat for "a few days" because the cat had just been removed from a neglect situation and needed help. For three years the cat lived in a closet because the elderly women owner couldn't handle the fights between her other cat and this one. For the first month, the new cat wouldn't leave her cat condo and spent most of her time hiding in her soft cave (a shell like bedding where the cat could climb inside and not be seen). When she finally decided to leave her condo, she was terrified of the dogs and other cats. The dogs left her alone, but my older cat ( a female around 14 yo) hissed at her whenever she came close. There have never been any real fights, just some hissing from opposite sides of a room. It took a few months, but eventually, the new cat - named Darla - learned she was safe and began to relax. She even discovered that if she climbed into the Pit's bed, he provided a nice warm body against which to sleep. She's returned to full health and appears well-adjusted and

no longer fearful. She still doesn't play with the other cats, but they manage to get along without fighting or hissing. Darla eats well, often stealing food from the dogs as well as from the other cats when they aren't around. She remains shy around new people, but otherwise seems happy. 

Okay, so here's the weird new behavior part: she's taken to sitting at the bottom of the stairs at night screaming her head off. She's part Siamese and very loud. At first the dogs would go down to investigate and she would shut up until they came back upstairs. The other two cats sleep in the bedroom, sometimes on the bed, other times with the dogs. Darla could come up and sleep here too, but won't. I tried moving a small cat condo into the bedroom, but she howled all night long. I suspect she's lonely at night, but why won't she just come upstairs? The other cats ignore her when she does come upstairs and, as I said, they don't fight anymore at any time. Darla gets plenty of attention during the day and seems happy most of the time. But at night, once we go to bed, she grows impossible. It's driving us crazy and I don't know what to do. I even tried leaving the other two cats downstairs in their "room" (Our guest room is where they are fed and where we keep the box) but Darla still screamed all night. Does anyone have an idea of why she is doing this and what we might try to help her AND us get some sleep? 

I really don't have an answer to this, but wanted to acknowledge your post and welcome you to TCS..

So it's been several months since things have settled and she's happy, and only now has she begun the crying at night?  And she will do it where-ever you put her?

I don't suppose you could put her in a room with the dogs, since she seems to settle when they are there - but I'm guessing you've tried that.

I know it's only at night and does not appear to be illness-induced, but a vet's visit could at least eliminate that possibility.

Thank you, Mani, for responding.

Darla is free to come and go in the house. The other cats usually sleep in the bedroom, as do the dogs. My Pit used to go downstairs when Darla began to scream, but now he ignores her. The Shepherd wakes up, looks down the stairs and sometimes tries to "herd" Darla up to the bedroom. This never works and the dog gives up and goes back to bed. I've tried shutting the door to the bedroom so Darla has to stay in the room, but this seems to freak her out and she paces and cries. (A different cry from the scream she makes) I also tried putting Darla in her cat condo, but she still screamed. 

Our horse vet is a cat lover and used to treat small animals as well as livestock. She was here last week and took a look at Darla to rule out any medical reason for her odd behavior. The vet saw nothing of concern other than bald spots on her back. These spots are left overs from when she was so confined and have mostly healed. The remaining spots are quite small (they were very large) and should heal completely. At no time did the spots appear to hurt Darla. I have an appointment with my small animal vet later this week for one of my dogs. I plan to call today to ask if I may also bring Darla. But she's been seen numerous times over the past year for various medical issues related to her previous neglect and the vet seems happy with her progress. 

You really are doing all you can for her.. she's very lucky to have found you.

I'm laughing at your Shepherd trying to herd her. 

Have you tried things like Feliway or other calming aids?  I've had luck with Composure for redirected aggression in my boy - that's not all it's used for.

What happens when someone sleeps on the couch?

Sinbad does this primarily when he has nightmares.

There is one other time when Sinbad does this as well though, it might be applicable to you? He has respiratory problems, so his sense of smell is not very good. This means that when I am in bed, completely under the covers, he can't find me because my 'present' smell is masked by the general me smell of my bed. If that makes sense. 

In both cases it's related to his inability to find me - he takes a super long time to wake up, and when he has nightmares it's an even longer process for him to be fully cognizant, so after a nightmare he seems to have no idea where he is for a while.

I'd be curious to know the answer to @Handsome Kitty's question as well.

Thanks for all the responses! We have all sorts of rescue animals around here (we have a small farm) and all my cats have been rescues. My older female came after being hit by a car and deemed paralyzed. She was in rough shape and we didn't know if she would survive. But three days after she arrived, I came downstairs in the morning to find her in the kitchen. She'd been in the spare room because we didn't want her bothered by the other animals. Thirteen years later I still have no idea how she opened the door! She was walking without trouble and acting very hungry. The vet thought the paralysis may have been caused by internal bruising or perhaps she was still in shock. Whatever, she recovered quick and had never been sick since. My other female was a feral cat who showed up some years ago and decided to winter over in the shed. She wouldn't let anyone close and come summer she disappeared only to reappear that fall. Even in the worst weather she wouldn't come to the house. A few years ago she decided it was safe to live on the deck and we put out a winterized dog house for her. She would allow me to come close, but no one else. Time passed and she became less fearful, but still wouldn't come inside. This past winter -- one of the roughest in years -- she showed up at the door the evening before a huge storm blew in. I was worried about her because the forecast was for very severe weather. I opened the door to check on the dog house and she skirted into the house. For two days she remained hidden, but then came out, claimed the dogs and decided being an indoor cat suited her just fine. She's never even tried to go outside since then. Darla came in rough shape and was very fearful. But, like the others, she's settled in and seems happy and secure. She prefers the dogs to the other cats, but otherwise does well. 

I haven't tried compose or the other calming aids, but I think I'll pick some up and give it a try. The weird thing is she doesn't appear terribly upset or stressed. I've never had a Siamese cat, but after reading about the breed, I wonder if the screaming is just her Siamese coming out. Darla doesn't have any trouble finding us -- she'll come upstairs and get up on the bed for a minute before heading back downstairs. If she were a dog, I'd say she wasn't getting enough exercise during the day. So, now I'm trying to keep her more active during the day when I'm home. None of us have tried sleeping downstairs and probably won't since the sofas aren't long enough for an adult body. I think it means something that she didn't start doing this until recently and has been here a year. She is much more secure and outgoing now than when she arrived. Back then, whenever a new person came into the house, she went into hiding. Now she's the official welcoming cat and comes running to see who has come into "her" house. I don't know, I think cats and all the other animals are just weird sometimes! Much like people.