Any advice for a tired sleeper?

My wife has been having issues during the last year with sleeping. She typically has been sleeping a solid 7-8 hours each night, but she is waking up exhausted. She has never had issues in the morning, so we have tried a few things so far, but she is still waking up feeling like she has not slept enough. The tiredness stays with her throughout her work day, so when she gets home and we get the kids to bed, she is usually completely exhausted:

1. We changed our mattress to a firmer mattress because she was having back pain (she is only 110 lbs, but I thought our sagging mattress could have have contributed to it).
2. She changed her pillow to a more comfortable pillow.
3. We keep our room cooler
4. She typically spends her last hour awake trying to relax. Limited screen time.
5. To my knowledge, she is not a snorer. I am, but not enough that my snoring is keeping her up at night.
6. She had previously used a fitbit to track her REM cycles, but they didn't show anything out of the ordinary.

I was just wondering if anyone has any suggestions on either sleep aid devises or any strategies that work for them. She does seem to have sinus problems if she sleeps flat, so it could possibly be something with that. Just trying to help her get some refreshing sleep.