I had an old cat that started peeing in her sleep. She also started seeking out warm spots to sleep, like on top of the TV, and on top of me. Not a good idea to pass urine on an electrical appliance, so I put a hot water bottle in her cat house and she was happy with that.
Anyway, blood tests showed she had kidney failure and was passing so much dilute urine that she couldn't control it when she was asleep. She was given medication to slow down the progression of the disease, but unfortunately, she got progressively sicker and weaker and developed dementia and I had to have her euthanased. I miss my little Sammie to this day. She was an adult stray when I adopted her, so I don't know how old she was exactly, but I had her for 16 years.
Best of luck with your cat.
Chirley
Urinary incontinence only during sleep is uncommon in cats. It could signify that your cat has a developing neurological problem in her back (lumbar spine), such as Cauda equina syndrome, or that she has a transitional cell tumor of the bladder, or that she may have feline urologic syndrome, also known as Interstitial Nephritis, or some other less common cause.
Perhaps trying the treatment for interstitial nephritis may be of benefit. This includes: an antibiotic for secondary bacterial urinary tract infection, Amitriptyline, feline cosequin, and other medications. An appetite stimulant may also be necessary. The protocol for interstitial nephritis is worth a try as a therapeutic trial, and if it is ineffective than further diagnostics may be necessary.
Acupuncture and Chinese herbs may help, as well as kitty diapers.
......this forum won't let me say p-u-s-s-y!
This is maybe in the wrong forum? We do dogs here. Some people here might know about cats too, but in the cats forum you might get better answers.
But this little cat sounds lovely. Get her checked at the vet's, just in case there is any bladder problem, or some other physiological problem going on. I certainly wouldn't get her put down, not unless she was in great pain, or the situation was terminal illness, or great future suffering. And I heard recently, it is possible to get little (don't laugh!) pantie-things, which incontinent animals can wear.
It made me smile, the thought of this sweet little *****-cat in her doggy t shirt.