My friend was diagnosed with idiopathic hypersomnia, which basically means that she needs to sleep a LOT (around 11 hours/day) or else she'll feel exhausted. Oh yeah, and it's "idiopathic", which means the doctors have no idea what causes it in her case.
She's in her 30s and willing to try out weird ideas in the spirit of self-experimentation. She's tried Vitamin-D supplementation and cutting out gluten, for instance. (Neither helped.)
Does anyone have any experience with hypersomnia or have any ideas for things for her to try? She's been struggling with this for years and it borders on debilitating.