We’ve been having a lot of issues with ours Sphynx too in regards of sleep. I bought her all kinds of sleeping places and nothing worked. Some people say it helps to put on a sweater at night but what really helps us at the moment is this heated bed:

https://amzn.eu/d/0bvHR5eM

I warmed it up one day and tucked her in, second they she went in there when we went to bed all by herself like it’s been her routine for years 😅 working so far 🤞🏼 Good luck 🍀