How many hours a day should a woman of 96 be in bed and / or sleeping?

I would say as many hours as she wants. My mom at 96 went to bed about 6 and was up at 6. She didn’t nap in her bed during the day. Maybe in her chair. I encouraged her to nap during the day, to put her feet up. She had CHF. But she chose to stay up and awake. Often there are posters here who say their parent sleeps almost all the time. I think it’s important that she is not in pain. Otherwise I accept that the person is very tired and prefers to sleep.