My friend's around 35 weeks pregnant. How many hours of sleep is essential for her? And how can she manage to sleep with the big belly as it's uncomfortable. Any suggestions?

Sleeping on her sides would definitely help or prop some pillows under her head to ease heartburns. I woke up multiple times bcoz I had to pee/was uncomfortable so the longest sleep I had uninterrupted was maybe 3-4hours? As long as she doesn't feel too tired the next day or too lethagic, she would be fine.