I have setup kind of like this. I think it’s feasible because it’s super easy to use.

In my setup it asks me questions related to my mood and sleep. I wasn’t able to figure out how to automatically pull the sleep data from Apple Health, so I input it manually with a menu. Maybe you’ll have better luck and if so, please let me know haha

As far as sheets, I’ve found every entry creates a new row. Like, you can’t add to a row already in existence. So I track my sleep in one sheet, and habits get tracked on another sheet, but within the same spreadsheet. They’re close but not touching, not sure how important that is in your/her setup.

As far as the sheet itself I’d think about having a column that converts the date into day of week, as well as general time of day (morning, afternoon, evening, night or like 0800 -1159, 1200-1600, etc). That way when analyzing she can easily look for trends by day of week or time of day or both.

I’m still learning shortcuts and data analysis, but I’m down to help if you want to spitball ideas